Geranium Care

The geranium, Pelargonium xhortorum, is widely grown in flower beds, containers, and hanging baskets. A wide variety of flower and foliage colors are available. From the true orange flower of ‘Orange Appeal’ to the fluorescent shade of ‘Orbit Violet’ there is surely a color to coordinate with any landscape plan. Flowers are packed densely on umbels rising above the plant foliage. Flowers may be single, double, or semi-double. In past years, most varieties were grown vegetatively from cuttings. Today, many varieties are available from seed. Plants grow 12 to 20 inches tall. Some of the named series, such as ‘Elite’ and ‘Orbit’, are known especially for compact growth which is desirable for containers and bedding displays.

Geraniums grow best in full sun. They like moist, well- drained soils and prefer a cool root zone. To keep flowers coming continuously throughout the summer, regular deadheading is necessary. Remove the spent flowerheads as they begin to deteriorate. This will prevent seeds from forming and force the plant into producing additional blooms. It also improves plant appearance as well as reducing the chance for disease.

Like all plants, geraniums have their share of disease and insect problems. One disease being seen this season is bacterial leaf spot. This disease is caused by the bacterium Xanthomonas pelargonii and is especially prevalent in warm, wet weather where plants are grown in crowded conditions. Disease symptoms include small (pinhead size), circular or irregular, brown, sunken spots on older or lower leaves. Large numbers of spots will occur on a single leaf, these will coalesce killing a large portion of the leaf which will then drop off. As the disease moves through the plant, the lower leaves wilt and yellow. In severe cases, the stem will possess black stem cankers killing the upper portion of the stem. Leaves infected with bacterial leaf spot should be removed as soon as it is noticed. Severly infected plants should be removed. There is no chemical cure for bacterial leaf spot. Make sure and destroy infected plants and plant parts this fall.

Another common disease of geranium is a fungal disease known as botrytis leaf spot or botrytis blossom blight. It is caused by Botrytis cinerea. Botrytis is favored under cool, moist conditions or where plants are watered frequently. Leaves develop zonate, brown leaf lesions which develop a grayish brown mass of fungal spores. The lower leaves will yellow and rot. Flowers may also become infected. They show discolored petals which wilt and fall. Remove affected leaves and flowers. Fungicide sprays, when environmental conditions are favorable, will help reduce levels of this disease. Chlorothalonil (Daconil 2787) is widely available for homeowner use and will help to control botrytis. Rust, root rots, stem rot, and leaf spots are other diseases known to infect geraniums.

Insects that frequently attack geraniums include aphids, cabbage loopers, and fall cankerworms. The four-lined plant bug, scale, and slugs can also cause damage. Properly identify the insect pest and control with the recommended insecticide.

Geraniums are one of the most popular annual plants grown by gardeners today. Proper selection, location, and care will keep them blooming and healthy all season long.

This article originally appeared in the July 29, 1994 issue, p. 124.


Wayne Handlos, Ph.D.

aphids ^ budworms ^ mealybugs on ^ leaf & ^ root white flies Geranium rust

There are a few pests and diseases that may attack the garden geranium/pelargonium. Most are easy to recognize and control, but a few may be more troublesome.

Aphids, sometimes referred to as plant lice or green fly, may attack geraniums. These small insects have sucking mouth parts and tap into the plant�s vascular system and suck out the nutrients that they need. They tend to be found on the youngest, most succulent tissue (actively growing stems and leaves including flowers). The aphid�s reproductive rate may be high (it is higher at higher temperatures and males are not essential to the reproductive process) so you should be vigilant. They excrete the excess sugar in the sap they suck from the plant. This sticky material provides a base/food source for fungi and is the origin of black deposits (called sooty mold) on the leaves of the plants. A simple control method for aphids is to spray the plant with a dilute soap solution (1 tablespoon of soap/detergent in 1 gallon of water). Commercial soap solutions are available for use on plants.

Mealy bugs are small, crawling insects that are covered by a cottony mass which they secrete to protect themselves. They also are sucking insects and do best where the tissues are soft. They are more common where the stem and leaf join and resemble little tufts of cotton. They can be killed by wiping them off with a cotton swab dipped in alcohol.

Whiteflies are also tiny insects with sucking mouth parts. They live on the undersides of leaves and are whitish in color as their name suggests. Whiteflies are most troublesome on regal geraniums and flourish in moist areas with little wind.

Caterpillars of several types attack zonal geraniums in particular. The bud worm flourishes on flower buds but will also attack young shoots. Frequently they will enter the flower bud and eat all of the petals so the plant does not appear to bloom. If you examine the buds closely you will find a small hole indicating the presence (or former presence) of the tiny caterpillar. They tend to be somewhat seasonal and squashing them is a very effective control method. An organic spray, specific for caterpillars, contains a bacterium referred to as BT or Bacillus thuringiensis will kill the caterpillars but does not harm people or pets.

Spider mites, very tiny spider or mites, may become a problem on plants grown under dry conditions. With mild infestations they tend to be found on the undersides of the leaves and look like tiny, moving dark specks. In heavy infestations they cover the leaves with a fine web.

Various sprays may be used to control some of these pests. Check with local agricultural experts or Master Gardeners for recommendations. Neem oil, a natural extract from a tropical tree, controls many problems including aphids, mealy bugs and rusts. Other fragrant essential oils may also be effective against various insect pests. Read the labels and buy something with which you are comfortable. Effective control may require repeated applications of the spray.

There are a few diseases that may affect Pelargoniums. Rust, a fungus (Puccinia pelargonii zonalis), is a common pest of zonal geraniums. It looks like rusty, brown spots on the undersides of the leaves. It is more common when the leaves are wet as this provides conditions for the germination of the spores. It is most easily controlled by prevention. Do not allow the leaves to remain wet for long periods of time. In other words only water plants in the morning so that they will dry off quickly. Neem oil may provide an element of control during rainy periods of the year, otherwise pick off and destroy infected leaves.

Botrytis is a fungus that affects primarily dead and dying tissue. It becomes troublesome during rainy periods and is most commonly found in flower clusters where there are old petals. The fungus feeds on the dead tissue and then may attack living tissue and kill the developing flower buds. Control this problem by dead-heading old flowers and flower stalks or keeping the plants dry.

Sooty mold, fungi growing on the excrement of aphids and whiteflies, was mentioned above and is directly related to infestations of aphids and whiteflies. Eliminate the insects and sooty mold will not develop. Unsightly leaves may be washed off or removed.

Various stem and root rots develop in plants in poorly drained soil or pots in standing water. Control is through prevention. Once the fungus is established in the roots, the plants are doomed. Good soil drainage is the best method of prevention.

Oedema or edema may be a problem with ivy geraniums. It is characterized by watery bumps on the leaves of ivy geraniums. It is related to an excess of water in the soil. It is not caused by any disease organism. Some cultivars are more resistant to edema than others and you can avoid the problem by not over-watering your plants.

There are many chemicals available to control insects. In general we would recommend that you use the “greenest”, most environmentally friendly solution available. Cultural techniques that produce the healthiest plants are the first line of defense. Beyond that, use mechanical methods if you can (pick off the creatures). After that, use organic, naturally occurring products like BT or neem oil. If you must use a chemical spray, use the most specific type available (one that attacks only the pest that is causing a problem). Again consult with experts or Master Gardeners before using a chemical spray and follow the directions precisely.



Rating: 5.0

Geraniums bring the brightest of colours to the garden and are among the most generous of plants. They continue flowering for months and when they begin to look tired, a cut back and good feed will start them off all over again.

Most of what we commonly call geraniums are actually pelargoniums but few gardeners are worried about this minor technicality – they’re too busy enjoying the plants!

Where to grow geraniums

An open, airy situation with plenty of sun is ideal for geraniums. This helps the plants in two ways. First, the sun promotes and encourages plenty of flowering. As well, a light, open position helps the plants to stay free from disease.

Geraniums are often at their best in containers. Growing geraniums in pots guarantees drainage and also get the plants up away from the ground where they’re less likely to be attacked by fungal diseases. Well-drained pots (like Yates Tuscans with their copious drainage holes) are a must.


Garden geraniums are renowned for their ease of propagation. Simply snip off a piece about 10 cm long and put it into a pot filled with Yates Black Magic Seed Raising Mix. Wait a few weeks and you’ll have a new plant.


Geraniums do best if they’re not given too much nitrogen-rich fertiliser (which tends to cause soft, leafy growth rather than flowering). Instead, from spring through till autumn, feed the plants regularly with Yates Thrive Flower & Fruit. Available as a soluble powder or a liquid concentrate, Thrive Flower & Fruit encourages flower production and improves disease resistance.

Pests and diseases

Geraniums are most susceptible to disease when the weather is warm and wet. As already mentioned, fungal infections can largely be avoided by growing the plants in an open, sunny position. The most common disease found on geraniums is rust, so-named because of the rust-like bumps that appear on the leaves. Yates Fungus Gun or Rose Gun will help take care of this problem.

Botrytis, or grey mould, can also spoil the flowers, especially if the weather stays wet for any length of time. Affected flowers grow fluffy, grey beards, before turning brown and shrivelling. Pluck off and destroy affected flowers and spray with a general purpose fungicide such as Yates Nature’s Way Fungus Spray.

White fly is a tiny, moth-like insect pest that is found in vast colonies on certain types of geraniums. Spray with Yates pyrethrum-based Insect Gun, taking care to apply underneath leaves as well as on top. Pyrethrum will also help to get rid of any caterpillars that might be thinking about attacking your geranium plants.

This area is for general comments from members of the public. Some questions or comments may not receive a reply from Yates. For all consumer related enquiries, please contact us.

Geranium Diseases: Treating A Sick Geranium Plant

Geraniums are one of the most popular indoor and outdoor flowering plants and are relatively hardy but, like any plant, can be susceptible to a number of diseases. It’s important to be able to identify diseases of geranium, if and when they do occur. Read on to learn more about the most common geranium problems and the best methods of treating a sick geranium plant.

Common Geranium Diseases

Alternaria Leaf Spot: Alternaria leaf spot is marked by dark brown, water-soaked circular spots that are ¼ to ½ inch in diameter. Upon examination of each individual spot, you will see the formation of concentric rings, which are reminiscent of the growth rings you see on the stump of a cut tree. Individual spots may be surrounded by a yellow halo.

The most common course of treatment for geranium problems like this is an application of fungicide.

Bacterial Blight: Bacterial blight presents itself in a few different ways. It can be identified by its circular or irregular shaped water-soaked spots/lesions, which are tan or brown in color. Yellow wedge-shaped areas (think Trivial Pursuit wedges) can also form with the wide part of the triangular wedge being along the leaf margin and the point of the wedge touching a leaf vein. The bacterium spreads into the vascular system of the plant via the veins and petioles of the leaves causing them, and eventually the entire plant, to wilt culminating in stem rot and death.

Plants infected with bacterial blight should be discarded and good sanitation measures should be practiced, especially with gardening tools and potting benches – basically anything that may have come in contact with the diseased geranium.

Botrytis Blight: Botrytis blight, or gray mold, is one of those geranium diseases that seem to be prevalent when the weather conditions are cool and damp. Usually one of the first parts of the plant to become infected is the blossom, which turns brown, initially with a water-soaked appearance, and may transition to being covered with a coating of gray fungus spores. Affected blossoms fall prematurely and leaves touched by the descending petals will develop leaf spots or lesions.

Prune off and destroy infected plant parts and keep the soil surrounding the plant clear of any debris. Fungicides may be applied at the first sign of disease to help curtail its spread.

Pelargonium Rust: Unlike leaf spots and blights, which may be hard to discern from one another, rust fungus is fairly easy to identify. Reddish-brown pustules develop on the underside of leaves with yellow areas forming directly over the pustules on the leaf’s surface.

The removal of infected leaves and an application of fungicide is the best means of treating a sick geranium afflicted with rust.

Blackleg: Blackleg is a disease of young plants and cuttings that is pretty much unmistakable. It is mentioned here because stem cuttings are a very popular and easy way to propagate geraniums. The stem of the geranium rots, starting out as a brown water-soaked rot at the base of the stem which turns black and spreads up the stem resulting in a rapid demise.

Once blackleg takes hold, the cutting must be immediately removed and destroyed. Precautions can be taken to avoid diseases of geranium like blackleg by using a sterile rooting media, disinfecting tools used to take stem cuttings, and taking care not to overwater your cuttings as a damp environments can foster the disease.


Pelargonium hortorum

Cutting Rot (fungi and bacteria): Geraniums are grown from seed but often propagation is done with cuttings. Cuttings are susceptible to invasion by numerous soil-borne organisms, and, thus, treatment of cuttings with a fungicide is often necessary. Allowing the cuttings to “heal” before planting will help reduce stem rot. Wound healing takes place if cuttings are laid on damp sand in heavy shade for approximately three hours. Bacteria (Xanthomonas sp.) and fungi (Pythium sp., Rhizoctonia sp., Fusarium sp., and Botrytis sp.) cause stem rot. They may infect stems singularly or in combination.

Black Leg (fungus – Pythium spp.): Generally a disease of cuttings and young plants. Stems and petioles blacken and a soft rot develops. Rotting starts at the base of the stem and may extend well above the soil line. Plants wilt and die. Symptoms progress rapidly. Control may require sterilizing potting mix and tools. Treat cuttings with a fungicide. A soil drench may retard spread of the disease in propagating benches.

Botrytis Blight (fungus – Botrytis cinerea): Affects blossoms, leaves and stems. On flowers, petals darken at edges and wilt prematurely. Affects central florets first. If humidity is high, spore masses may be found on flowers and leaves. Spots on leaves are irregular, brown and have a water-soaked appearance. Botrytis will cause a soft rot of cuttings. Proper sanitation in greenhouses by removing and destroying infected plant material will prevent spread. Use of a foliar fungicide when conditions are favorable for infection will help to prevent the disease. Improving ventilation and air circulation among the plants will also reduce infection.

Rust (fungus – Puccinia pelargonii): Rust occasionally is found on cultivated geraniums. Distinct, reddish pustules form on the underleaf surfaces in a circular pattern. The upper surface is yellow in areas where pustules form. Control rust by removing infected leaves and spraying with a fungicide.

Bacterial Leaf Spot and Stem Rot (bacterium – Xanthomonas campestris pv. pelargonii): Leaf spots begin as small, water-soaked spots on the underside of leaves. Spots become well defined and slightly sunken in a few days. Necrosis and wilting of the entire leaf follows, but the spots do not coalesce. Another symptom is rapid wilting of the leaf margin resulting in an angular pattern bound by the veins. Stem rot begins with one or two branches showing wilt. Eventually, the entire stem turns black with only a few leaves remaining at the terminals. Within the stem, the vascular fibers remain intact but the support tissue around the fibers is destroyed. Controls consist of using disease-free plants for cuttings, controlling the humidity in greenhouses, avoid wetting leaves when watering.

Viruses: Several viruses are known to affect geraniums. They cause mosaic patterns, mottling, crinkled or cupped leaves. Rogue out diseased plants as soon as they are noticed and use disease-free plants for propagation.

Oedema (physiological): At first, oedema appears as water-soaked spots on bottoms of leaves which later become corky and brown. The leaves may turn yellow and fall off. Oedema is caused by moist, warm soil and moist, cool air or cloudy conditions that result in more water being absorbed by roots than is being transpired by the leaves. As a result, cells swell and burst. Avoid over-watering and increase ventilation.

Why Are My Geranium Leaves Turning Red?

Zwilling330/iStock/Getty Images

When summer approaches, garden centers brim with colorful geraniums (Pelargonium spp.) ready to brighten hanging baskets, window boxes and sunny borders. Grown throughout the United States as an annual, this tender perennial is hardy in U.S. Department of Agriculture plant hardiness zones 10 and 11. Geraniums grow quickly, flower profusely and delight seasoned and beginning gardeners. If your geranium’s foliage turns red, a few simple fixes can get the problem under control.

Understanding the Warnings

Red geranium leaves signal the plant is stressed in some way. This may be because the plant is receiving too much water or too much sunshine, or has been planted outdoors too early or in mineral-deficient soil. Geraniums that are planted too close together also tend to develop red leaves. Diagnosing the problem requires examining your geranium’s care, and adjusting your regimen accordingly.

Checking Moisture

Red leaves are often caused by geraniums receiving too much water. These plants tolerate drier soil, and should be planted in well-draining pots and kept barely moist. Potted geraniums often suffer from sitting in full saucers and getting waterlogged. Red leaves develop. Always let water run through the pot. Then dump all the excess from the saucer. If overwatering or waterlogged conditions are not corrected, the red geranium leaves begin to drop.

Addressing Light

Geraniums love sunshine, but intense rays can sometimes be too much. When placed in sites where light is too strong, geranium leaves turn red as a defense. The oldest leaves are affected first. Moving potted plants into semi-shaded areas or providing shade during early afternoon, when sun is hottest, remedies the situation.

Managing Cold

Cold weather turns geranium leaves red, especially when plants are set out too early in the year. Plants that have been grown indoors from seed or as cuttings should be exposed to colder outdoor conditions gradually. If your geranium leaves turn red right after outdoor planting or relocation in spring, it likely is because of cold. In fall, red leaves signal evenings are chilly. It is time to move geraniums back to the greenhouse or to take cuttings for next year.

Handling Nutrition

Fast-growing geraniums have small root systems that are vulnerable to deficiencies of phosphorus and trace minerals. Treat slow-growing, red-leaved plants with a high-phosphorus liquid fertilizer every two weeks during the growing season. For example, mix 1 tablespoon of water-soluble, 5-15-15 fertilizer with 1 gallon water to offset deficiencies and encourage blooms. Cold temperatures inhibit the uptake of trace minerals in geraniums, so correct any cold temperature issues before you treat.

Solving Geranium Problems

How To Use This Problems Section
The chart is organized to give you a quick and dirty summary of the possible symptoms that you may encounter. Those problem causes for which we have full files will be linked to those files. Those causes with no link will have a paragraph below the chart helping you deal with that particular problem.

Solving Geranium Problems
Symptom Probable Cause
Small Holes In Unopened Buds Geranium Budworm
No Blossoms Overfeeding; Excessive Heat
No Blossoms Indoors Poor Environment
Lower Leaves Have Yellow Edges Needs Fertilizer
Leaves Deformed Mites
Leaves Turn Reddish Nights Too Cold
Spindly Plant Growth Low Light
Buds Dry Up; Drop Off High Humidity or Overwatered
Pale or Yellow Spots; Leaves Distorted Aphids
Plant Grows Poorly Mealybug
Plant Weakens; Leaves Turn Yellow Whitefly
Leaf Spots of Various Sizes; Leaves Wilt; Stems Rot Leaf Spot or Rot, a fungal disease
Leaves Patched or Coated with White Mildews, fungal disease
Foliage Turns Yellow Root rot, bacterial disease

Geranium Budworm

Small Holes In Unopened Buds Signals Geranium Budworm
Also known as the tobacco budworm, the geranium budworm is a caterpillar that tunnels into unopened buds and eats them from the inside out. Then when they open, the flower petals are riddled with holes. To prevent the spread of the worms into healthy buds remove any buds showing tiny holes and nearby brown specks. Handpick any visible worms, which may be greenish, tan, reddish or black depending somewhat on the color of their host flower. They have 2 pale stripes running parallel to each other the length of their bodies.
For heavy budworm infestations spray Bt (Bacillus thuringiensis) on the bud surfaces where budworms are feeding. They will ingest the bacteria, which only harms caterpillar type pests, sicken, stop eating, and die within days. For chronic budworm problems, cover the soil with landscape fabric to block the larvae (the worms) from entering the soil where they overwinter and become moths. Plant geranium seedlings in holes cut through the fabric. Ivy geraniums are less susceptible than other geranium types.

Excessive Heat

No Blossoms Due to Overfeeding or Excessive Heat
Overfeeding stimulates lush vegetation but no flowers on geraniums. Water the plants generously so that the ground is thoroughly soaked two or three days in a row so that the excess nutrients will be diluted and carried past the geranium roots deeply into the soil. Do not fertilize for the rest of the growing season.
While zonal types of geraniums thrive on sun and hear, ivy and regal types of geraniums stop blooming when subjected to the extremely high temperatures typical of hot sunny afternoons in warm climates. Try to local them where they will get some shade in the afternoon. No Blossoms Indoors Due to Poor Environment
There are three reasons why geraniums may be reluctant bloomers indoors in the winter: 1). too much nitrogen, 2). too little light, 3). too little difference between day and night temperature. Stop feeding the plants for awhile and find a better location for them. It may be necessary to place them under lights to encourage blooming in the winter.

Low Nutrition

Lower Leaves Have Yellow Edges Signals Low Nutrition
If their bottom leaves have yellow edges, geraniums probably need some food. Spray their foliage with liquid fertilizer, but do not exceed the dilution prescribed on the container. Feed them every two weeks until the symptoms disappear.

Nights Too Cold

Leaves Turn Reddish When Nights are Too Cold
Leaves of geraniums placed outside too early in the spring may redden when the plants are first planted or set outside. This is caused by a sudden chill, usually at night. Delay moving your plants outside until nighttime temperatures remain reliably above 40°F.

Low Light

Spindly Plant Growth Is Due To Low Light
Geraniums become spindly because of a number of environmental problems. Insufficient light is a common cause. Failure to pinch back long stems, excessive feeding and watering and overcrowding will also cause geraniums to look leggy and to fail to thrive.


Buds dry up, drop off Due to High Humidity, Overwatering
Sometimes, especially on potted geraniums, the unopened buds dry up and drop off before they have a chance to open. This may be because they are too moist. Try to provide a drier climate for them. Wait a bit longer between watering, especially if they are in containers.

Root Rot

Root rot is caused by fungi that live in the soil. Typically, these rots attack geranium stems at or near the soil level. Plant foliage turns yellow, wilts, and dies. Root systems rot, causing the geraniums to topple over. Remove and discard infected plants, or cut away affected plant parts with a clean, sharp knife or razor blade. Disinfect tools after use. Keep the garden clear of old plant debris and keep mulch away from stem bases. For long term prevention, lighten heavy soil with a mixture of perlite, vermiculite or peat moss to improve its drainage. Avoid overwatering. Space plants further apart to prevent crowding. Use sterile commercial soilless potting mix in containers.

Leaf geraniums: leaves with white, yellow, and red variegations

Geraniums, besides the flowers, have also beautiful leaves. Unusual shapes and unexpected colours. Genetic defects or congenital diseases colour them in white, yellow and red variegations.

Texto © Giuseppe Mazza

English translation by Mario Beltramini

It would not flash to anybody’s mind to organize a “collection of mongoloids”, or of, generally, of beings with congenital malformations, but a frequent impairment of the living beings, the albinism, attracts irresistibly the man, who is, it’s known, looking for “oddities”.

Apart the mice, the hamsters and the rabbits, as white like snow, which have a bad hearing, and even a worse eyesight, with their poor red eyes, where appears all the network of the blood capillaries, due to the total absence of pigments, have come out, in all the world, “zoos for albinos”, and for a white young lion, born recently in South Africa, they have reached a record quotation of 300.000.000 Liras.

In the Green World, the albinism is an even more dramatic event, because if, for a genetic disorder, a plant comes to birth with white leaves, that is, lacking of chlorophyll, is not in condition to effect the photosynthesis,, and, once exhausted all the reserves of the seed, will die, miserably, of hunger.

Only the partial albinisms do survive: subjects with leaves partly bleached or more whitened, which operate at a reduced rhythm, or branches with wholly white leaves, which get, within some limits, the nourishment from the leaves, more or less green, which surround them.

To these categories belong the most of the “leaved geraniums”, often frail creatures, impaired, which would not resist, in the wind, to the evolutionary pressure, but are stubbornly selected, by men, for ornamental purposes.

And if, by chance, a branch regresses to the primary form, if, by a miracle, is able to get over, and to put its chromosomes in order, we find then pitiless manuals of horticulture suggesting to eradicate it, so that the handicap can be handed down, by cutting, with the applauses of the collectors.

The selections in this way date back, mainly, to the last century, and the nurseries have today Golden Leaved Geraniums, with the lamina uniformly short of chlorophyll; Bi-coloured Leaved Geraniums, with matching of yellow and red, yellow and green, black and green, and green and white; and Tricolour Leaved Geraniums, where are displayed several tones of yellow, green and red, often superposed, which can originate 4-5 different colours.

Among the most celebrated “golden”, are the ‘Golden Crest’ and the ‘Hunter’s Moon’, but they do not have many lovers, because their yellowish colour, turning to grey, is not strange enough to be alluring, and, at first sight, recalls a rather dubious health status.

The “bi-coloured”, are by sure more pleasant, and, when the leaves are normal, and the mutation is limited to an elegant white small hem, the plant is vigorous and floriferous.

This is the case, for instance, of the ‘Caroline Schmidt’, created in Germany about one hundred of years ago, with double flowers of a nice bright red; of the ‘Chelsea Gem’ of 1880, almost identical in the leaves, but with pink double flowers; or of the well known ‘Frank Headley’, of 1957, which, even if being dwarf, beats every record of flowering, with pink-salmon corollas with a traditional look, which cover the leaves almost completely.

Equally rich of chlorophyll, is the ‘Preston Park’, with pink simple flowers, a delicate indentation on the margins, and an unmistakable dark “ring”.

The ‘Galway Star’, with a flower analogous to the Pelargonium crispum, from which it derives, distinguishes for the engraved leaves with white-cream margin; and the ‘Crystal Palace Gem’, with red or pink simple flower, which concentrates the photosynthesis in a green “butterfly”, at the centre of the yellowed leaves.

This spot becomes gilt in the ‘Happy Thought’, a dorm with red simple flowers, created in England in 1877, and becomes pink in the ‘Medallion’, born in 1956, from cross breeds with the Pelargonium frutetorum.

Here the capacity of photosynthesis is very scanty, and in fact, unluckily, this is a very delicate plant.

Similar remarks do apply also for other “golden bi-coloureds”, such as the ‘Selby’, with a central red ring and pink double flowers zone, and two varieties of the end of the nineteenth century: the ‘Golden Harry Hieover’, with the tough and bright leaf which reveals a sure relationship to the Pelargonium peltatum, and the ‘Mrs. Quilter’, more resistant, with pink simple flowers, and where the zone extends almost up to the border.

The ‘Golden Ears’ is one of the rare “Golden Leaf Stellars”. It carries a red, simple flower, and, often, the brick coloured zone extends almost till the edge, with spectacular effects.

Among the white and green bi-coloured, stands out the ‘Madame Salleron’, with leaves hemmed of white, chequered, and sometimes wholly albinic, on branches which live at the nearby leaves expenses. Created in England around the 1840, and tall not more than 20 cm, was employed for borders; and apart two mutations with straight stems and insignificant pink flowers, the ‘Little Trot’ and the ‘Mrs. Newton’, it has not enough strength for blooming.

Another super anaemic of the year 1880, the ‘Freak of Nature’, clearly a “trick of nature”, survives, nobody knows how, with the photosynthesis reduced to the edges of the foliar laminae, and even succeeds in blooming, with red simple corollas, in incredible contrast with the spectral white of leaves and stems.

Last unusual bi-coloured, is the ‘Crocodile’, made precious by a thick yellowish network. Selected in 1964, in Australia, belongs to the group of the Ivy Geraniums, and is not affected by albinism, but by virosis. A non-infectious disease for the other plants, which it carries with itself since the birth, and shows, dramatically, the lymphatic vessels.

To the tricoloured, belongs, for instance, the famous ‘Mr. Henry Cox’, created in England in 1879, with roundish leaves, and pink-salmon simple flowers, and the ‘Mrs. Pollock’, born, always in England, in 1858, with red orange simple flowers, and leaves deeply lobed. Both present a great variability, but, in the whole, the second one is more robust.

All these geraniums, with a metabolism reduced by the lack of chlorophyll, have obviously a rather slow growth, and like a seriously ill patient which needs oxygen, they require a lot of light for completing their wonky photosynthesis.

On the other hand, the usual rules are in force, with the caution that, normally, they are more exposed to the diseases. In winter, they must be sheltered in luminous verandas, because the lack of light transforms the golden yellow of the leaves in a fatal greyness, and the same happens if we exceed with the fertilizers, which, in any case, must be scarce, proportioned to the growth, poor of nitrogen and with a rich contents of potassium.

He who does not feel like setting up a “hospital for geraniums”, and loves unusual leaves, has, anyway, many possibilities also with the normal plants, rich of chlorophyll. The ‘Chocolat Peppermint’, perfumed of mint and chocolate, displays, just to say, oak-shaped leaves with an elegant dark zone, and this tendency is even more evident in the ‘Royal Oak’.

The Pelargonium barklyi, a botanical geophyte, which in winter, disappears under the ground, shows roundish leaves more decorated than a lace; those of the Pelargonium myrrhifolium coriandrifolium, imitate the look of the Coriander; and he who loves the forms, super indented and slender, without reaching the exaggeration of the Pelargonium denticulatum, has available several hybrids such as the x asperum, with leafy branches which reach the refinement of the ferns.


Geranium with Brown leaf edges.

Thank you for your question about your geranium. The most common problem that geraniums with brown leaf edges have is a lack of water. Most garden stores sell little probes that tell you whether the soil is dry or wet.
The yellowing of the leaf, between the healthy (green) and dead (brown) tissue is called chlorosis, or a lack of nitrogen. This pattern is also indicative of an iron/manganese toxicity, which happens when the pH of the soil is too low (acidic.) I suggest you get an inexpensive soil pH tester, to see if the pH of your growing medium is between 6.0 and 6.6 (water is 7.0, so this is just slightly acidic). If the pH is below 6.0, you can add just a little lime (calcium carbonate) to the top of your soil, and mix in a bit.
However, they can also develop leaf problems such as these if they are consistently watered with tap water that has been chlorinated. Here is a to an article that explains the benefits of rainwater compared to ‘treated’ water. You might try watering with rainwater (not that we have some) or spring fed water.
In the meantime, cut off the leaves that are browning, and hope that the few weeks we have left in the summer will mean more healthy leaves.
Hope this is helpful. Good luck!

Add a burst of color to your garden.

Proper care for geranium plants isn’t difficult. What most people think of when they hear “geranium” is more accurately called pelargonium. There are many different varieties of geraniums (pelargoniums) which fall into five categories:

  • Zonal
  • Fancy
  • Ivy
  • Scented
  • Regal

For the most part, their basic care is the same.

Basic Care for Geranium Varieties

Whichever variety you select, you will find that most can be grown from zones four through nine. Just be sure that the temperatures in your zone are reaching 70 to 85 degrees when you plant your flowers. Most geranium failure is due to planting too early in the season.

Proper care for geranium plants includes providing full sun from six to eight hours a day. They prefer moist, well drained soil, and you’ll need to allow them to dry out between watering or the roots can rot.

Fertilizing regularly is also an important part of geranium care. Monthly feeding with a 10-10-10 fertilizer will keep them happy. You can also use a water-soluble fertilizer about every third watering.

Planting Geraniums

Avoid selecting plants that have long, leggy stems or brown roots. Find a healthy, green plant with buds to bring home. Geraniums should be planted level with the surrounding soil in dirt that has been mixed with peat moss or compost. More organic material should be added each year.

Be sure your geraniums are spaced far enough apart to accommodate their full growth. Over-crowded plants are prone to disease. Once in the ground, firm the soil and water thoroughly. Water should be at the root of the plants, not over the top. Mulch should also be used to help keep roots cool and to help keep soil moist.

Geranium Diseases

While they are pretty hardy plants, sometimes geraniums are susceptible to fungal diseases. One such disease is called bacterial leaf spot which is caused by the Xanthomonas bacteria. Typically this disease is caused by warm, wet, crowded planting areas. If you see pinhead-sized, sunken, brown spots remove and destroy the leaves affected. For severe infections you will need to remove and destroy the entire plant.

Botrysis leaf spot and blossom blight are other fungal diseases that you may discover in your geraniums. Caused by the Botrytis cinerea fungus, this disease is found in cool, moist conditions. Affected leaves form brown areas that develop grayish-brown spores. Affected flowers have discolored petals that fall from the plant. Remove affected parts of the plant and spray with Daconil or a similar product.

Common Pests

There are a few pests that you might find infesting your garden, many of which can be controlled naturally. Some common pests include:

  • Aphids-can be controlled with ladybugs
  • Slugs-controlled with shallow trays of beer that attract and drown the slugs
  • Budworms-can be hand picked as can any type of caterpillar

Other Common Problems

There are other problems that you might encounter with your geraniums. Usually though, they have simple solutions. Plants that don’t seem to bloom after being brought home usually require more light. Remember, proper care for geranium plants includes six to eight hours of full sun each day.If the lower leaves of your plant are turning yellow, this could be an indication of too much water. Don’t forget to allow soil time to dry out between watering. Working organic matter into the soil can help improve drainage.

Yellow leaves over the whole plant can mean that you plant needs fertilizer. Usually by this point, the geranium has been in need for some time. Expect a few weeks to see improvement after providing fertilizer.

Small holes in the flower buds are caused by budworms. These can be hand picked. Pesticides can also be used such as Sevin or Orthene, but these should be used with caution, as should any chemical.

Explore Your Options

Once you understand the basic care of geraniums, you will find that they are easy to grow and enjoyable to have around you home and landscape. Try some different varieties like Cranesbill, Rosebud or some of the other scented varieties that have a fragrance like lemon, peppermint, apple or nutmeg. All are sure to brighten your day.

By Virginia Brubaker|March 27, 2014

Start Slideshow 3 photos 1 of 3

Edema on zonal geraniums Advertisement

Edema om Ivy Geranium. Photo credit: SHS Griffin

Diagnosing rust on geraniums can be a challenge for growers. Rust begins with yellow spots on the underside of the leaves and can rapidly progress with brown fungal spores called pustules in the center of each spot. The pustules are raised up off the leaf surface and feel rough to the touch. As the pustules grow, they produce a distinctive concentric ring. The areas on the upper leaves above these spots will also turn yellow, then eventually brown. If left untreated, infected leaves turn yellow and dry, and drop prematurely, resulting in defoliation of the plants.


Combinations of cultural and chemical control are required to control geranium rust. Splashing water and handling are the main factors in spreading this disease. Avoid splashing water and minimize handling of infected crops. Likewise, avoid carrying over geranium stock and never bring geraniums into the greenhouse from outside, as these are also common avenues of infection.

As soon as an outbreak is detected, remove all obviously infected leaves from the plant and carefully take them out of the greenhouse in sealed bags. Immediately treat all of the geraniums with a fungicide such as Camelot O, Compass, Daconil, Disarm O, Eagle, Heritage, Spectro, Strike, Pageant Intrinsic, Phyton, Protect or Terraguard. Repeat this sequence on a weekly basis, rotating modes of action (MOAs) to avoid resistance, until pustules are no longer appearing.

Or Is It Edema?

Edema occurs predominately during cool, damp and low-light conditions. Some growers have dealt with the high cost of fuel by turning back the thermostat, which increases the relative humidity that contributes to edema. Edema results from an imbalance in osmotic pressure inside the plant cell. If this pressure inside the geranium plant is great enough, it can cause the cells to rupture, creating scab-like wounds. Ivy geraniums, for example, typically display brown, corky lesions on the undersides of the leaves. In severe cases, the leaves turn yellow and may fall off.

Preventing edema requires the management of environmental conditions. Do what you can to reduce the relative humidity and keep the air moving with HAF fans. Running the soil dry can aggravate edema, so strive for even soil moisture. Maintaining adequate fertilizer keeps cell walls more flexible. Improved ventilation, along with warmer, sunnier weather as spring progresses, often reduces the occurrence of new symptoms.

Virginia Brubaker () is GGS Pro Technical Support Supervisor for Griffin Greenhouse Supplies. See all author stories here.

Series: Bulls Eye™, Elite™, Maverick™, Pinto™, Multibloom™, Orbit™, Orbit Synchro™, Ringo 2000™

1. Soil and pH Needs

Geraniums are very adaptable and will grow in almost any kind of soil. The soil should be open and porous to allow for good water drainage, oxygen penetration, and healthy root growth. A heavy soil will benefit from the incorporation of several inches of peat, compost, or perlite before planting. Do not use manure or vermiculite. A sandy soil will also be measurably improved by the addition of organic matter. Soil should be amended with fully composted organic matter prior to planting and in the case of clay soils the addition of pea gravel equal to at least 25% of the soil volume will aid in aeration. If adding organic matter, be aware that organic matter that has not been fully composted will tie up nitrogen and sulfur leading to nutrient deficiencies and poor growth. Soil pH should be mildly acidic 6.5 is ideal and should be tested prior to planting but after adding any amendments. This can be done quite easily with a portable pH tester available for about $100. Mix one part soil with two parts distilled water, stir well and wait thirty minutes, then follow the instructions for using the pH meter. If pH is too low, the addition of lime is warranted. However, the rate will vary depending on how much you need to raise the pH and the type of soil you are dealing with. Clay soils or those with a lot of organic material have a high buffer capacity and require more lime than sandy soils, which have a low buffering capacity. A good soil testing lab can determine the lime requirement index (LRI) of your particular soil and can recommend types and rates of lime to use. The frequency of watering will depend on the type of soil, weather conditions and the amount of mulch. Mulch will not only reduce soil water evaporation but will also reduce splashing of water onto the lower leaves, moderate soil temperatures and reduce weed competition.

2. Fertility

Geraniums are moderate feeders and will not bloom if over-fertilized. An application of a balanced controlled-release fertilizer (CRF) such as 10-10-10 at 2 pounds /100ft2 or 5-10-5 at 4 pounds/100ft2 can be incorporated into the soil at planting. A half-rate application of this dry fertilizer can be applied at mid-season. Water these dry fertilizers into the soil after application. In high pH soils (alkaline soils) additional iron or iron sulfate may be beneficial to reduce chlorosis (yellowing) of the foliage. Yellow foliage on geraniums may also be caused by a nitrogen deficiency within the plant. Both can be corrected with the proper supplemental fertilizers.

Edge burn due to high soluble salts

3. Disease

Geraniums have their share of disease problems. Bacterial leaf spot is caused by the bacterium Xanthomonas pelargonii and is especially prevalent in warm, wet weather where plants are grown in crowded conditions. Disease symptoms include small (pinhead size), circular or irregular, brown, sunken spots on older or lower leaves. Large numbers of spots will occur on a single leaf; these will coalesce killing a large portion of the leaf which will then drop off. As the disease moves through the plant, the lower leaves wilt and yellow. In severe cases, the stem will possess black stem cankers killing the upper portion of the stem. Leaves infected with bacterial leaf spot should be removed as soon as it is noticed. Severely infected plants should be removed, there is no chemical cure for bacterial leaf spot.

Botrytis blossom blight is another common fungal disease of geraniums. It is caused by Botrytis cinerea. Botrytis prefers cool, moist conditions or where plants are watered frequently. Leaves develop zonate, brown leaf lesions which develop a grayish brown mass of fungal spores. The lower leaves will yellow and rot. Flowers may also become infected. They show discolored petals which wilt and fall. Remove affected leaves and flowers. Fungicide sprays, when environmental conditions are favorable, will help reduce levels of this disease. Rust, root rots, stem rot, and leaf spots are other diseases known to infect geraniums.

Bacterial leaf spot on geranium

Geranium leaf with Botrytis

4. Insects

Insects are usually not a problem for geraniums, as their strong, bitter scent keeps most bugs from bothering them. The most common insect pests are:

Aphids – small green ovate insects usually clustered together at the growing tip of the plants. A good indication of aphids includes small new leaves, small white outer-skin skeletons from the insect (molts), and sticky honeydew on the leaves. The honeydew can sometimes become blackish.

Spider Mites –usually found on the underside of the leaves, very often within their delicate webbing. Spider mites cause speckling damage on the leaves and sometimes cause the leaves to have brown corky areas.

Caterpillars – most caterpillars do their work at night. Look for circular holes in the edges of the leaves, freshly chewed flower stems, dark brown to black excrement left on the surface of the leaves.

Bud Worms – look for small round holes in the new buds or for the small (1/4″ –1/2″) worms actively feeding on the buds. Wherever you see small moths or butterflies in and around the plants, expect to see bud worms several weeks later.

Bud worm damage to flower buds

Mite infestation on geranium foliage

5. Tips for Success

  • The most important requirement for growing geraniums successfully is a location with at least 6-8 hours sunlight per day. The more shade they receive, the fewer flowers they’ll produce.
  • Whenever feasible, it’s a good idea to remove faded flowers, including the portion below each flower where seeds will develop. This practice, called “deadheading,” encourages blooming by preventing seed maturation. Although it may not be practical to deadhead masses of geraniums in the garden, it’s a must for flowering annuals in containers. Deadheading not only helps prolong blooming, it also keeps plants looking fresh, healthy and well-groomed.
  • Geraniums are resistant to drought and don’t require a lot of water. Take care not to overwater your plants. When you do water, do it early in the day and water only the roots. Wetting the leaves can make them more susceptible to infection with spores from other plants
  • Remove weeds from the plantings that compete with the geraniums for moisture, nutrients and light.

Information provided by Syngenta Flowers

Geranium (Pelargonium spp.)-Alternaria Leaf Spot

Cause This fungal disease, caused by Alternaria alternata, has not been formally reported from the Pacific Northwest but has been found on a few samples sent to the OSU Plant Clinic. The disease is favored by prolonged cool, moist conditions and low nitrogen fertility. Older leaves are particularly susceptible if they are senescing. The fungus survives on dead leaves on the soil surface and spores are spread by air currents.

Symptoms Dark brown, irregularly shaped spots appear on leaves. Spots range in size from barely visible to 0.33 inch in diameter. Larger spots may show several dark concentric rings within the spot. Spots may be surrounded by a diffuse yellow halo. Spotting is mostly on the lower leaves, although new growth may be affected. Numerous spots close together on leaves may coalesce. Severely infected leaves shrivel, turn black, and fall off. Only leaves are affected.

Cultural control

  • Space plants for good air circulation.
  • Remove and destroy infected leaves and fallen plant debris.
  • Maintain optimum plant fertility.
  • Water at base of plants and/or with drip irrigation. Do not wet foliage.

Chemical control Use just before conditions favor disease development.

  • Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. H
  • Broadform at 4 to 8 fl oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
  • Chipco 26019 N/G at 1 to 2.5 lb/100 gal water. Group 2 fungicide. 12-hr reentry.
  • Compass O 50 WDG at 2 to 4 oz/100 gal water. Do not use organosilicate additives. Group 11 fungicide. 12-hr reentry.
  • Copper-Count-N at 1 quart/100 gal water. Oregon only. 48-hr reentry general or 24-hr reentry for greenhouse.
  • CuPRO 5000 at 1.5 to 5 lb/A. Group M1 fungicide. 48-hr reentry.
  • Daconil Weather Stik at 1.4 pints/100 gal water. Group M5 fungicide. 12-hr reentry.
  • Disarm O at 1 to 4 fl oz/100 gal water. Group 11 fungicide. 12-hr reentry.
  • Eagle 20 EW at 6 to 12 fl oz/100 gal water. Group 3 fungicide. 24-hr reentry.
  • Exotherm Termil at 1 can/1500 sq ft of greenhouse. It ignites to form a vapor that condenses back on the plants. See label for details. Group M5 fungicide. 24-hr reentry with no ventilation or 12-hr reentry with ventilation.
  • Fame SC at 1 to 4 fl oz/100 gal water. Group 11 fungicide. 12-hr reentry.
  • Heritage at 4 to 8 oz/100 gal water plus a non-silicone-based wetter sticker. Group 11 fungicide. 4-hr reentry.
  • Mancozeb-based products. Group M3 fungicides. 24-hr reentry.
    • Fore 80 WP at 1.5 lb/100 gal water plus a spreader-sticker.
    • Protect DF at 1 to 2 lb/100 gal water plus 2 to 4 oz spreader-sticker.
  • Medallion WDG at 1 to 2 oz/100 gal water. Use with oils or adjuvants may damage plant. Some geranium cultivars may become stunted or chlorotic when higher rates are used. Group 12 fungicide. 12-hr reentry.
  • Monterey Liqui-Cop at 3 Tbsp/gal water. H
  • Mozart TR at 1 can/4,500 sq ft of greenhouse. Group 12 fungicide. 12-hr reentry with no ventilation.
  • Myclobutanil 20 EW T&O at 6 to 12 fl oz/100 gal water plus spreading agent. May observe a PGR effect. Group 3 fungicide. 24-hr reentry.
  • Nu-Cop 50 DF at 1 lb/100 gal water. 48-hr reentry. O
  • Orkestra at 4 to 6 fl oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
  • Pageant at 4 to 8 oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
  • Spectro 90 WDG at 1 to 2 lb/100 gal water. Group 1 + M5 fungicide. 12-hr reentry.
  • Terraguard SC at 4 to 8 fl oz/100 gal water. Group 3 fungicide. 12-hr reentry.
  • Trinity TR at 1 can/3,000 sq ft of greenhouse. Group 3 fungicide. 12-hr reentry without ventilation or 4-hr with ventilation.
  • Zyban WSB at 24 oz/100 gal water. Not to be confused with the smoking cessation drug. Group 1 + M3 fungicide. 24-hr reentry.

Reference Strider, D.L. 1985. Diseases of Floral Crops, vol. 2. New York: Praeger Publishers.

Geraniums (pelargoniums) are now coming into flower with their brightly coloured flowers. If the flowering is not as good as expected, it might be that the plant requires a position with more light. Although geraniums are often classed as plants that take plenty of sun, flowering seems to be better if they are growing in a position of part sun. Geraniums are affected by few pests and diseases. However, one of them is prevalent just now. Rust, a fungal disease, causes yellow-orange raised spots, initially on the underside of the leaves. The spots are caused by spores that develop on the leaves. As the disease progresses, the tops of the leaves display yellow spots, spoiling the look of the leaves. If affected leaves are left on the plant, they eventually become quite disfigured and eventually fall from the plant. Prevention is the best treatment, providing a sunny position with good air movement. Rust develops when the leaves are moist. Therefore, watering the plants in the morning, so the leaves have time to dry, is a good strategy for trying to avoid the development of rust. If rust-affected leaves do appear, they should be removed from the plant by breaking them at the main stem. In this way, the leaves come off cleanly, without damaging the stem. The affected leaves should be disposed of in the general rubbish, rather than being placed in the compost where the rust spores can affect more plants. Garden hedges, such as those that have been made from plants such as lily-pillies, camellias, westringias or golden durantas should now be shaped or pruned as they rapidly produce their new spring growth. This will encourage increased numbers of new shoots, with a resultant thick, rich appearance. Older, thicker branches can be removed, while retaining stronger, more supple growth to maintain the desired growth and shape. A variety of tools can be used, including trimming the plants with hedge-cutters, either electric of manual, and cutting individual stems with a pair of secateurs. The material that has been removed will generally be too soft for use as cutting material at this stage of its growth. An application of Seasol will encourage new growth by feeding the root system. Cymbidium orchids that have multiplied and now fill their pot will have reduced flowering as they will gradually become starved of needed nutrients. Once the plants have been removed from their pot, which may take some effort if they are very overgrown, the old “soil” should be removed from the roots. Then the plant should be divided into smaller plants, making sure each one has some older shoots as well as one or two strong new shoots that will eventually produce the flower spikes. Older and damaged roots should be cut from the plant. It is advisable to sterilize the secateurs in between treating plants in an effort to avoid the transfer of diseases. Perhaps the most important thing to remember when repotting orchids is the medium that is placed into the pot with the plant. Orchids require a very free-draining mixture as their root system will quickly rot if it has been placed into heavy soil. A mixture of small to medium sized pine bark is good to use. This will allow the water to flow though as well as letting the roots breathe. Cymbidium orchids should be fed with Campbell Orchid Special Fertiliser (blue form) from now until December. Then the yellow form should be applied. The fertiliser should be made into a solution using 15g in 5 litres of water and applied, particularly to the leaves, about every two weeks. It is important to allow the fertiliser to drain through, and away from, the pot. If the pot is allowed to sit in a saucer or similar container containing excess fluid, there will be a build-up of salts around the base of the pot.  This will be evidenced by a layer of white material around the base. An excess of salts will eventually be detrimental to the health of the plant. The Native Frangipani originates from rainforest areas between Sydney and the Tablelands areas of Cape York. It is an open and upright growing tree that reaches 20 metres when it is growing in rainforest areas, where it has to compete with other trees for light. However, when growing in suburban gardens and parks, the trees generally only reach eight metres. Native Frangipani trees display their five petalled flowers that are up to 50cm across, for about six weeks, during spring. The flowers open as a cream colour, then darken to a yellow as they age, giving the tree a multi-coloured effect. The flowers are produced in clusters and have a pleasant fragrance that might be considered to be similar to that of exotic frangipanis. The leaves are evergreen and display a shiny dark green upper surface with a paler green underside. Positions of full sun to part shade are suitable for Native frangipanis. Regular pruning from planting can be used to encourage the development of dense foliage as well as masses of flowers. Planting the tree in an area adjacent to buildings will allow the fragrance to be enjoyed on the evening breezes. Trees are fast growing and frost resistant.  Dwarf forms of the Native frangipani are sometimes available. [email protected] Maitland and District Garden Club

Leave a Reply

Your email address will not be published. Required fields are marked *