Cutting Back Rosemary: How To Trim Rosemary Bushes

While pruning a rosemary plant is not needed to keep a rosemary healthy, there are several reasons why a gardener might want to prune a rosemary bush. It may be that they want to shape the rosemary or reduce the size of the rosemary shrub or to create a more bushy and productive plant. Whatever your reasons for wanting to prune your rosemary, there are a few things you need to know about how to prune a rosemary bush.

When to Prune Rosemary

Rosemary pruning can be done anytime during the spring or summer up until four to six weeks before the first frost.

Pruning rosemary after this time, or in the fall and winter, can cause the rosemary shrub to focus on growing new, tender growth rather than hardening off and protecting the growth that it has. If a rosemary bush does not harden itself off, it will be more susceptible to winter damage which can kill it.

Tips for How to Prune a Rosemary Bush

Before you prune your rosemary bush, make sure that your pruning shears are sharp and clean. Blunt or dirty pruning shears can result in ragged cuts that can leave the rosemary plant vulnerable to bacteria and pests.

The next step in how to trim rosemary bushes is to decide why you want to trim the plant.

If you are trimming the rosemary to shape it, say as a hedge or a topiary, draw a mental picture of what you would like the plant to look like and trim away the branches that do not fall into that outline. If your shaping needs to remove more than one-third of any branch, you will need to prune the rosemary back in stages. You can prune back branches by one-quarter, but you will need to give them a season to recover before pruning again.

If you are looking to reduce the size, you can prune back the overall plant by one-third at a time. Then wait two to three months and you can prune back by one-third again.

If you are doing rosemary pruning simply to create a busier plant, you can remove the end one to two inches of the branches. This will force the branch to split and will create a bushier plant. This technique is particularly helpful if you are growing rosemary for cooking, as this creates more foliage in a more compact space.

You may also find that your rosemary plant is in need of some rejuvenation. Find tips for this here: Rejuvenating Rosemary Plants.

The steps for how to prune a rosemary bush are simple but important. Knowing how to trim rosemary bushes properly will help you keep your rosemary happy and manageable.

There is a lavender at the bottom of my street that has grown so wild it sprawls through the fence; you can see a line along the flowers where passersby can’t help but caress its fragrant blooms. I’m one of them. I like its dishevelled nature, but I’m not sure it would work in a garden. Its bare legs and gaping belly would make it unsightly.

Woody herbs such as lavender, thyme, rosemary and sage, as well as the less-woody-but-still-woody-enough oregano and winter savory (Satureja montana) do need pruning. Left to their own devices, they become leggy, with the woody parts bearing few or no fresh shoots.

In the Mediterranean heat, these herbs are clipped by nature – thin soils, baking summers and strong winds will keep them neat enough. In our wetter, milder climate they grow in a different manner, so it’s important to prune them regularly – once or perhaps even twice a year – to keep them in a nice shape.

The best time to prune is early spring, but there is a second chance now, once flowering is over. Remove the spent flowers and cut the stems back to a pair of leaves on no more than a third of the overall plant. Next spring, cut another third and you’ll find your herbs will stay in a good productive shape.

It is almost impossible to get back to a neat, bushy plant once it’s grown big. This is because the woody parts tend not to resprout new growth; if you chop back into this, you will be left with stubs and little else. In this case, it is better to take cuttings or start again than to try to renovate the shrub.

Cuttings are easy enough, though. Choose non-flowering growth and cut sections of stem that are 10-15cm long. Remove the lower pair or pairs of leaves so you have a clean stem, then, with a sharp knife, cut just below a pair of leaf nodes (the point from which the leaves grow). Then place cuttings in gritty seed compost (mix equal parts grit and compost) and water well. Place them in a warm, shaded spot and keep well watered. Or, if you are taking the cuttings indoors, place a clear plastic bag over them to retain moisture.

In a few weeks you should start to see roots at the bottom of the pot. If not, carefully invert the pot and check what’s happening in the soil. The RHS website has a good page on herb cuttings if you are nervous.

If your lavender suddenly turns into an awkward leggy teenager, then it is possible to cheat and do the “dropping” trick if it is not too big. Dig up the plant, dig a deeper hole and replant so that only the leafy growth is showing; essentially you bury the woody stems. (Do not try this on a hot day or if the plant is in flower.) The soil must be gritty, otherwise the stems will rot. Keep the plant well watered till you see signs of new growth.

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Rosemary is a great addition to any herb garden, however, it does require annual pruning to keep it looking at its best.

The main reason for an annual prune is to help slow down the formation of wood and extend the vigour and lifetime of your rosemary.

The best time of year to prune rosemary is just before growth starts in mid-spring after any risk of frost has passed.

Pruning at this time of year should avoid any frost damage to new growth, and any pruning scars that occur will be covered by new foliage in the growing season ahead.

Rosemary can be pruned from mid-spring right up until four to six weeks before the first frost in the autumn.

If rosemary is pruned after this time, it can cause the shrub to focus on growing new, tender growth rather than hardening off and protecting the growth that it already has.

If a rosemary bush does not harden itself off, it will be more susceptible to winter damage which can kill it.

One advantage of an early autumn prune is that it will encourage good air circulation, which guards against your rosemary rotting.

Rosemary blooms in late spring to early summer, and if you lightly prune after its first flourish of flowers it will more than likely bloom again in late summer.

How To Prune Rosemary

Before embarking on a rosemary pruning session make sure your secateurs are nice and clean, and sharp. Ragged cuts caused by blunt and dirty blades could leave your shrub open to infectious diseases or pests.

The shaper your blades, the cleaner the cut you will achieve, rewarding you with branches that grow back stronger.

A Light Prune Or Trim Of Your Rosemary

If you wish to give your shrub a light or a hard prune the first port of call should be to remove branches that have crossed and those that are dead and diseased.

Cut stems that have been frost damaged back to the first set of healthy leaves. Do the same for low-lying branches that show signs of fungal infection, such as drooping or discoloured foliage.

If the entire branch appears to be affected, it’s usually best to get rid of the whole thing to keep the condition from spreading.

To produce a nice bushy foliage, lightly trim your plant by cutting back two to three inches from the outer most stems. This should encourage the stems split in two, producing a nice bushy shrub.

Avoid cutting below the lower leaves and into older wood, as removing too much foliage can harm your rosemary, causing it to grow only woody stems.

Shaping Your Rosemary

Shaping your plant is one of the main reasons for trimming your rosemary. You may wish to shape it as a topiary or a hedge.

You can shape your shrub as desired, keeping the depth and angle of each cut consistent will give your rosemary, a neat and well-manicured appearance.

Try to avoid making it too uniform though, as rosemary is naturally bushy, so it’s ok for it to be a little thicker in some places.

You may wish to focus on one part of the shrub for a practical prune. For instance, your rosemary may be overtaking a nearby plant or overhanging on to a pathway, cutting back those sections will help open things up creating space.

Hard Pruning Your Rosemary

Before you give your rosemary a hard pruning, it is best to evaluate whether to cut it back or if it has become too woody, replace it with a new edition.

If your rosemary has become overgrown and needs rejuvenating start by lopping off any stems that are dead, diseased or are no longer producing foliage.

Overgrown shrubs can be cut back a third of their total size. Cutting back your rosemary by more than this could kill it off by leaving only non-productive foliage.

If you want to reduce the size of the plant further, wait six to eight weeks before cutting back the rosemary again by another third.

If you wish to keep your plant the same height, you can also cut every third stem to thin it out without affecting the overall dimensions of the shrub.

The practice of cutting out a significant amount of foliage from this woody shrub is known as “rejuvenation pruning,” and can be useful for saving shrubs or trees that are failing due to exposure to harsh weather or disease.

How To Harvest Your Rosemary

If you wish to harvest your rosemary for some sprigs for your Sunday roast, the best time to do this is just before it flowers, as this is when the flavour of the rosemary will be at its peak. If you also plan to dry some rosemary this is also the best time to so.

When trimming look for stems that are at 8 inches (20cm) in length, and do not take cuttings from newly grown stems.

Cut sprigs off that are around two inches long, making sure you don’t cut too close and always leave some foliage on the stems.

To ensure you always have enough mature stems to clip, it is a good idea to keep more than one plant in the garden. Two or three should be more than adequate for most households.

Never harvest more than a 1/4 of your rosemary bush at a time. Leaving at least 3/4 of your plant will ensure that it continues to thrive and produce new sprigs.

When drying your cuttings, tie them together in evenly sized sprigs and hang them in a dark, dry and well-ventilated part of your house.

After around ten days your rosemary should be completely dry and ready to take down to strip off the leaves and store in a jar or an airtight container.

Also if you cut sprigs for harvest while your plant is in bloom, you can use the flowers for cooking as well, as apparently, they are edible as well.

Growing Rosemary From Cuttings

As mentioned before it is a good idea to keep more than one rosemary in your garden if you plan on using it for harvesting, but instead of purchasing more plants why not grow your own from cuttings from the plant that you already have planted in your garden.

Even if don’t use your rosemary for harvesting, you can grow free plants from the cuttings that you take from your annual prune of the shrub.

There a couple of valid reasons for growing rosemary from cuttings:

Earlier Harvest

A rosemary plant raised from a cutting will mature more quickly than a plant grown from seed, and rosemary seeds tend to have a low germination rate and take a long time to grow. A rosemary cutting will reach a usable size in just a few months, and be ready to harvest much more quickly.

Same As The Donor Plant

The plant you grow from a cutting will be an exact clone of the donor plant and have the same disease resistance, growth and flavour.

How To Take Cuttings From Your Rosemary

  • First, you need to select which stems to use from your donor plant. Choose healthy stems that have fresh growth, younger shoots will have green stems that are flexible. Avoid taking cuttings from woody stems.
  • Using secateurs take a cutting around 5 to 6 inches back from a fresh growing tip.
  • Gently strip off the lower 2 inches of leaves from the cutting.
  • Place the cutting in water and place in a warm position away from direct sunlight. Change the water every couple of days with room temperature water. The fresh water will provide dissolved oxygen that prevents the cutting from rotting.
  • The cutting should grow roots in a few weeks depending on the room temperature. After 6 to 8 weeks it should be apparent to see if the cutting has taken. Cuttings that have failed will be brown and will have shed leaves.
  • Pot up the cutting once roots develop, using a sandy soil mix that drains well. Mix equal parts of multi-purpose potting soil and sharp sand, or use cactus-potting soil.
  • Fill a 4-inch pot with slightly damp potting soil for each rosemary cutting. Use a pencil to make a 3 to 4 inch hole into the soil. Place the cutting in the hole with care to avoid damaging the roots. Cover gently and water thoroughly.
  • Place the newly potted rosemary plant in indirect light or in filtered sunlight until roots become established, and then move to direct light, at least 6 to 8 hours per day. Keep the potting soil moist until you see new growth.
  • Let the new plants to put on some growth before harvesting. Once the plant is 6 inches tall, harvest by cutting stems as needed. New growth will continue forming on the stem.

Growing herbs is a great way to add an edible element to your garden. Rosemary is normally quite easy to control if you keep it in a pot, but if you have it growing freely in the garden, it can easily get woody and shabby looking. This is when these tips for pruning rosemary are helpful.

All garden plants need pruning at some stage, and rosemary is no exception.

Rosemary is a perennial herb that I use all the time in cooking. It is earthy, flavorful and very hardy in the garden.

This herb can be grown in containers (I grow mine on my vegetable garden on a deck) or planted directly in your flower garden, or vegetable garden. It is versatile and adds great flavor to all sorts of recipes.

Generally, rosemary is fairly easy going and won’t need much in the way of care. However, if your plant is really overgrown, hard pruning may be necessary.(removing quite a lot of the old wood.) This technique is best done in the spring since it will send off lots of new growth and the long growing season to follow will help it.

But general pruning of rosemary can be done throughout the growing season and right into early fall. My plants get lightly pruned during the spring and summer, since I cut rosemary for use in recipes all year. By fall, the plant can look pretty unkempt so this is when I set about the task of pruning rosemary in earnest.

Tips for pruning rosemary

When to prune rosemary

This can be done as early as late winter and then through spring and summer. It’s not necessary to wait for the flowering to finish and, in fact, this is not a good idea. Pruning too late in the year might encourage new growth that will not have hardened before the first frost. In many locations, late July is a good time, and for warmer hardiness zones, you can prune in September. A general rule is to prune no later than about 4-6 weeks before the first frost.

Is pruning necessary each year?

Rosemary is very good at taking care of itself, particularly plants grown in pots. It’s not necessary to prune plants unless they are overgrown, over woody, or unless you are trying to make a hedge or prune into topiary shapes. Also, you may simply want to prune rosemary to reduce the size of the plant or to make your existing plant more productive next year.

My rosemary has quite a bit of older growth on it, so I want to prune it now so that the time I have left will give me some fresher tips to use in Thanksgiving cooking. Rosemary grows for me pretty much all year round, here in zone 7b.

How to prune rosemary plants

Before you start the job of pruning rosemary, be sure that your garden shears are nice and sharp. Dirty shears with blunt tips will mean that your cuts are ragged, which can encourage disease and pest problems. All garden tools need to be tended to this time of the year. Be sure to check out my general tips for winterizing your garden tools, as well.

General Pruning. To prune rosemary, clip off the faded flowers, if any. You can preserve the flowers with Borax for use in dried flower arrangements, craft projects or potpourri. Use a good pair of pruning shears to trim back just below the flower area. If the plant is not flowering, just snip off the top few inches of the stems, being careful not to move too far into the old wood.

If your aim is a bushy plant, just remove about 1 – 2 inches of all of the branches. This encourages each tip to split into two and will give you a nice bushy looking plant before you know it.

Hard Pruning. Since rosemary is a perennial,if it is grown freely in the garden can get to heights of 6-8 feet! Any plant this size will get woody and unkempt looking if not pruned.

Photo credit Flickr

If you decide to do more of a hard pruning, earlier in the year, ratcheting pruners will make cutting the old wood easier, but never cut more than 1/3 of the plant or you may kill it. With old wood, a good rule of thumb is one branch out of three. Then, 6-8 weeks later, as the new growth is growing vigorously, you can cut back another woody branch and so on. At all costs, don’t cut all the old wood off at once.

Pruning Rosemary Plants in Containers

Rosemary is a perennial herb, so it will continue growing year after year in containers. This can result in pot bound plants.

A pot bound rosemary plant will produce less and less new growth and get quite woody. Re-pot the plant into a larger pot, if you can. If not, remove the plant from the container and carefully prune the roots back and bit and add a fresh layer of soil. I find that I can grow rosemary for several years in a large pot before it needs this step..

What to do with rosemary clippings

Rosemary can be easily dried for use in recipes during the winter and, like most herbs, can be preserved many other ways. Rosemary oil and rosemary herb butter are just a few ideas.

You can also root the cuttings of newer shoots of rosemary to get more plants for free. Either place the springs in water to grow roots and plant them in soil, or use a root powder on the tips and plant them directly into soil. Before you know it, you’ll have a new plant. Rosemary makes a great indoor plant to grow on your kitchen counter near a sunny window.

These tips for pruning rosemary bushes are easy to do but important in the overall look and health of the plant. Knowing how to prune rosemary plants will make for a happy plant that gives you sprigs of lovely flavor for cooking.

Disclosure of Material Connection: Some of the links in the post above are “affiliate links.” This means if you click on the link and purchase the item, I will receive a small commission from the sale, but the price is the same for you. I am disclosing this in accordance with the Federal Trade Commission’s 16 CFR, Part 255: “Guides Concerning the Use of Endorsements and Testimonials in Advertising.”

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Rosemary has many culinary and ornamental uses. In the lower South, it is a handsome evergreen shrub. Rub its leaves and a pine fragrance fills the air. Rosemary’s unique aroma and flavor accent a variety of foods and crafts.

In the Landscape
A slow-growing, upright, bushy herb, rosemary often reaches 3 to 5 feet tall after several years of growth. The stems become woody with age and are covered with green needlelike foliage. Prostrate or creeping selections range from tiny small-leafed plants suitable for bonsai to large-leafed plants usable as a ground cover on a dry hillside. These rarely grow taller than 1 to 2 feet, with short, narrow leaves. They make excellent container plants, topiaries, or edgings for rock walls and terraces in the warmer areas of the lower South.

Rosemary flowers vary from white to pink to blue, and the blooming time depends on the selection. Plants that bloom in late spring or early summer attract bees; those that bloom in November and December are a delight during the winter holidays. Use rosemary as an evergreen hedge in Zone 8 and south. Farther north, grow rosemary in a container and bring it indoors to overwinter.

Planting and Care
This evergreen perennial thrives without winter protection in Zone 8 and farther south. In Zones 6 and 7, it may be damaged by severe freezes. Heavy mulching helps rosemary survive through winter, as does planting it beside a south-facing masonry wall. The wall will absorb the sun’s warmth and radiate heat at night, as well as shield the plant from north winds. If you live in a windy location, always choose a protected spot for your rosemary, because extreme cold in Zones 8 and 9 can kill the tops of this herb. Keep a rosemary plant in a container year-round in case plants in the ground are lost during a hard winter. However, beware that if the soil in the pot dries out and the plant wilts, rosemary does not recover.

Rosemary likes full sun but will tolerate partial shade. The best way to start rosemary is from transplants. Set plants out in spring as soon as the soil warms or in early fall. Rosemary needs light soil with a pH of 6.0 to 6.7; add lime, if necessary. Rosemary is suited to raised beds or containers as it requires good drainage. Mix a slow-release fertilizer with the soil before or during planting, and fertilize again the following spring.

Layering is an almost foolproof method of obtaining new plants once you have a planting started. You can also start new plants from stem cuttings in spring and summer. Starting from seed is not practical; seeds are slow to germinate, and the rate of germination is poor. It takes three years to produce a good-sized plant from seed, and seeds do not produce a predictable, dependable clone.

Rosemary likes evenly moist soil but is susceptible to root rot if kept too wet. Let the soil surface dry out between waterings. Mulch to keep roots moist in summer and protected in winter, but do not allow the mulch to touch the crown of the plant. Prune dead wood in the spring.

If you live in an area north of Zone 8, move rosemary to a protected location or bring it indoors for winter. Place in a cool spot, about 45 degrees, with bright sunlight. Water infrequently?just enough to keep the soil moist.

Species and Selections
Many selections of rosemary are available. These vary in form, flavor, flower color, and winter hardiness. Check with local sources for recommendations of selections that perform well in your area. Arp and Old Salem are upright selections considered to be among the hardiest. Prostrate types are generally less cold hardy and should be grown in containers or hanging baskets that can be moved to a protected location. While most types have pale lavender flowers, some selections of rosemary, such as Benenden Blue, Santa Barbara, Collingwood Ingram, and Tuscan Blue, have blue blooms that are quite showy. Try Albus for white blooms or Majorca Pink or Corsicus for pink.

Harvest, Storage, and Use
For fresh use, cut stems anytime. To dry the leaves, harvest just before the plant blooms. The flavor will be stronger, and it is the best time to prune plants. Dry stems on a rack, or bunch several sprigs and hang them to dry. Then strip the leaves from the stem. Rosemary sprigs also can be frozen or stored in vinegars and refrigerated oils.

Rosemary’s strong flavor combines well with other herbs, but use its leaves sparingly. Strip fresh leaves from stems, chop, and add as an accent in soups, meats, stews, or vegetables. Work rosemary into bread dough, or mix it with wine or olive oil and garlic for a marinade.

Rosemary can become a simple luxury when you drop a sprig into bathwater, add it to a bouquet, or wrap it around a napkin ring. Fresh rosemary works well in wreaths. Use dried rosemary in sachets. Burn a bunch of rosemary branches over charcoal when grilling to enhance the flavor of foods.

Troubleshooting
Rosemary is susceptible to powdery mildew and root rot, especially along the Gulf Coast. As a preventive measure, provide excellent drainage and good air circulation. Always clean the garden thoroughly in the fall, and promptly remove any diseased plants. Mealybugs, spider mites, and whiteflies can also be a problem.

Prune your rosemary once a month if you want to keep it the size of a shrub. COURTESY

Q: I use rosemary which I purchase from the store for cooking. It is expensive and doesn’t stay fragrant very long if I don’t use it all. I would like to plant rosemary in our yard so that I can use it in my cooking. Is there a difference between rosemary used for cooking and rosemary used in landscaping?

A: There are several varieties of rosemary but most are selected for landscaping rather than cooking. Many of the landscape varieties have horizontal or prostrate growth. However, these landscape varieties can be used for cooking as well. But varieties selected for cooking are usually upright and often have a higher oil content. Upright growth is easier to harvest.

Growing rosemary as an herb is different from growing rosemary as a landscape plant. Two traits are considered desirable in rosemary as an herb: upright succulent leaf and stem growth and a high oil content.

To grow rosemary for cooking, push new growth with nitrogen fertilizers and harvest before flowers are produced. Seldom is rosemary left to flower when used as an herb, but the new growth is dried or used fresh. Flowers may be attached when sold at farmers markets.

The best oil comes from rosemary flowers. However, most commercial oil production is from leaves and stems that produce more abundant oil, but it is inferior to the oil produced in the flowers. The same technique is used, except high phosphorus fertilizer is applied to improve oil production and harvesting is done when flowers are present for higher-quality oil.

Some of the better varieties for cooking include Benenden Blue, Flora Rosa, Tuscan Blue, Majorca Pink, Arp, Albiflorus, Huntington Carpet, McConnell’s Blue, Irene, Holly Hyde and Hill Hardy, to name a few.

Q: When is the best time to prune a rosemary bush? Our rosemary bush has grown too large. I would like to reduce it to about one-half of its current size. Also any suggestions about how I should prune it would be greatly appreciated.

A: If you are pruning it once a year, now is a good time. If you are pruning it as a hedge or you have to keep it under some sort of size control, then prune it once a month. If you are pruning it to use for cooking, cut it back now, let it regrow and harvest the new, succulent growth before it flowers.

You have a few alternatives for an overgrown plant. One is to cut the plant near the ground and let it regrow from 2-inch-long stems. Prune it now or just before new growth begins.

Another method to reduce its size requires more care. Trace the longest branch of the shrub inside the plant and remove it where it joins a main branch. Leave no stub. Select two or three other long branches on the inside and make the same kind of cuts. Prune every couple of years or when it gets too large.

Your third alternative is to replace the plant with something that doesn’t get so large.

After pruning, fertilize as you would to encourage new growth. One fertilizer application a year is all that is needed unless you are growing it as an herb that requires frequent harvesting. Applying too much fertilizer will dilute the oil content and fragrance.

If you are harvesting frequently, fertilize lightly every six to eight weeks with a balanced fertilizer containing nitrogen and phosphorus. Or apply your favorite compost to the base of the plant and get more spectacular results.

Q: I have a neglected privet that has overgrown its space. When and how far back should I prune it and keep its shape? My neighbor cut one back several years ago and it never came back at all.

A: Japanese or wax leaf privet regrows slowly after it has been pruned. If it is pruned deeply to the interior, where there is larger diameter wood, it is possible it may not grow back.

Your privet is overgrown and requires the removal of 12 to 18 inches of growth. It will recover very slowly from a pruning this severe. There is also a chance it may never recover in some spots.

In your particular case, this plant has simply outgrown the area it was given. It is time to remove it and look for something different.

Q: My rosemary plant has white foamy droplets on the stems. I can spray them away when I water with a hose but they return. They do not seem to be harming the plant but what is it?

A: The white foamy droplets are called spittlebugs and common on rosemary. They suck plant juices and are buried inside the spittle for protection. They can be knocked off the plant with a strong stream of water from a hose but they return quickly.

They are usually more of a nuisance than a problem unless you are growing rosemary as an herb. They can multiply and become a problem in the future so keep an eye on them.

Neem oil and horticultural oils will give some control of spittlebugs when sprayed directly on the plants. Spray a small section of the plant first to make sure the oils do not damage the rosemary.

Soap and water sprays wash the spittle off and leave these bugs unprotected. Follow this with an insecticide spray such as pyrethrum, which protects the plant from becoming reinfected. This might need to be done several times, a few weeks apart, to get them back under control.

Q: My Tuscan rosemary is in trouble. It appears to be dying.

A: Tuscan is a nice upright rosemary variety with good color and density that is grown for cooking and its oil content. It has very few insect and disease problems. We will occasionally see aphids and spittlebugs but nothing to get overly excited about.

Rosemary prefers soils that have been improved with compost and organic surface mulches such as wood chips. The soils must drain well. They do not like rock mulch at all and frequently die a few years after being planted.

When these plants die it is usually due to soil problems. Roots have a tough time “breathing” because of poor drainage. Most of the time these soil problems cause the roots and stem of the plant to die. The plant collapses during the heat of summer because roots are dead.

Avoid planting rosemary in low spots or where water accumulates. These conditions suffocate roots. It is possible to replant in this spot but remove as much of the soil as possible and replace it with the soil that drains easily.

This particular root disease may linger in this infected soil and cause future problems.

Q: I have an upright rosemary about 4 feet tall. It was sheared once on the top and the sides. It has never bloomed. Is there such a variety that never blooms or am I doing something wrong with this plant?

A: I have never heard of one not blooming. Most reasons plants do not bloom are planting them into low light levels (shade) or shearing them just prior to bloom. Normal bloom periods are spring and fall but in warm areas they might bloom all season long.

Prune during summer months if you want the blooms. Make sure it receives plenty of sun and do not plant in the shade. Avoid high nitrogen fertilizers but use fertilizers recommended for other flowering plants such as roses.

— Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to [email protected]

Rosemary (Rosmarinus officinalis)

Rosemary is an ornamental evergreen shrub with attractive, aromatic, deep green leaves and blue flowers in spring and early summer. Although it is usually thought of as a herb for use in the kitchen, it is a colourful and attractive garden plant in its own right.

Rosemary looks great in beds and borders and in Mediterranean planting schemes. It makes a perfect container plant for a sunny patio.

Rosemary can also be used to create informal hedges, and there’s even a low growing, sprawling variety that is good for ground cover – Rosmarinus officinalis ‘Prostratus Group’.

How to grow rosemary

Cultivation

Rosemary is easy to grow and look after. It grows well in relatively poor, well-drained soil and a sunny position. The sunnier the site, the stronger the scent from the foliage.

The best time to cut stems for use in the kitchen is in early afternoon, when their flavour will be its strongest.

Rosemary varieties

Although most varieties produce blue flowers, there are those with white flowers, such as ‘Lady in White’, and those with pink flowers, such as ‘Majorca Pink’.

Suggested planting locations and garden types

Flower borders and beds, patios, containers, city and courtyard gardens, hedges.

How to care for rosemary

Rosemary is fairly drought tolerant, but like all other drought-tolerant plants, needs watering until established.

Although reasonably hardy, plants may suffer in severe winters and in cold, exposed gardens.

Avoid feeding with high-nitrogen feeds, which encourages soft growth that is more susceptible to cold damage, so use balanced and high potash ones instead. The latter will encourage flowering and stronger growth.

Pruning rosemary

It’s a good idea to prune newly planted rosemary plants to encourage strong, bushy growth.

Established plants need little in the way of regular pruning, apart from removing wayward or overly long shoots. But cutting back plants by around one-third will help prevent plants growing too tall. Prune immediately after flowering.

Rosemary does not readily re-shoot from old wood, so never prune old, brown, leafless stems – otherwise the plant will die. Old, neglected plants are best replaced with new ones.

Pests

Rosemary may be susceptible to the following pests and diseases: Rosemary beetle, Root rot.

Flowering season(s)

Spring, Summer

Foliage season(s)

Spring, Summer, Autumn, Winter

Sunlight

Full sun

Soil type

Chalky, Loamy, Sandy

Soil pH

Neutral

Soil moisture

Well-drained

Ultimate height

1.5m (5ft)

Ultimate spread

90cm (3ft)

Time to ultimate height

6-10 years

prune a rosemary bush

It looks like the weight of the branches are doing this, but rosemary can get extremely woody and easily overtake and area without regular pruning. I would wait until mid-March to do any serious pruning, but if you want it to have a mounded shape, then you need to regularly prune to maintain that shape. What I would do is take a long look at the major branches and cut off those where the plant is spreading in a direction you don’t want it to grow. If it is looking thin in the center, then prune to where you can see new growth directed where you want to fill in.

Most woody herbs won’t send out new grow on bare wood stems (this is especially true of lavender, but rosemary is similar) and you will see that leaves drop as they get shaded. If you regularly prune to make sure the plant has an open structure, you make sure that the leaves that are there get plenty of light. With rosemary, you can easily snip out every other branch and still have a full-looking plant.

The good news is that if you go a little too far with the pruning, you can always purchase a new plant for not a lot of money and start over.

Rosemary Pruning Tips

Rosemary is a herb extensively used in cooking. If the plant is not being used extensively, and you want to control the growth, then you will have to start regularly pruning. Here are soem tips for successful rosemary pruning.

Tip #1 – New Growth Only

The one rule that you must abide by with rosemary is never to cut older, woody stems. Some plants will tolerate this, but rosemary will start to die. Only take off up to five inches at a time. The best time to prune rosemary is early spring or late in the fall, but regular attention to stems that are growing too long will keep the plant in order.

Tip #2 – Make a Tree

Rosemary can grow very large for a shrub and many gardeners like to prune them so that they look like small trees. As the plant grows, the shoots off the bottom of the main stem should be removed. As the growth continues the growing tips of the other stems should be snipped off. This will encourage lateral growth and you will soon have a very bushy top. The plant can be left to grow naturally or be trimmed back once it reaches the ideal size.

If clipping for culinary use or for drying, do not use any stems that were pruned in the last two or three weeks.

Tip #3 – Make a Shape

Rosemary can be trained into just about any shape you want. Instead of using wires or frames to get the effect that you want, start the shape planning as soon as the bush is big enough. It is best to let the shrub grow into the shape that you want. Try to envisage the shape and then only clip those stems that project outside the image you create. Some stems will appear to be growing at a faster rate than the others. Although not suckers these stems behave like suckers and should be cut right back.

Tip #4 – Don’t Worry about Mistakes

Because rosemary grows so prolifically there is little chance of making a mistake with your pruning. Even pruning the shrub right back will often see the plant recover very quickly. The next time you prune you will know what not to do.

Tip #5 – Constant Attention

Probably the best way to keep a rosemary bush in order is to start out with regular small scale pruning. The bush grows quickly and to snip it into shape as it grows can solve a lot of problems. Pruning once a year is not really necessary if the plant is allowed to grow into the shape that you want and controlled by weekly attention. The only time you should not prune is when the plant is flowering.

If your rosemary is in a pot or container, you might find that it is becoming a bit root bound. If repotting is not possible, or not wanted, you can remove the plant and carefully prune the roots and just put a shallow extra layer of soil in the pot.

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