How to Care for an Aster
Care for your asters with some basic rules of thumb, and be rewarded with spectacular blossoms in a variety of colors. Planting these wonderful stars (aster is Greek for star) will uplift and brighten your fall garden. This Michaelmas daisy (another name for the flower) produces blue, white, red, purple, pink and lavender flowers. Ranging from 8 inches to almost 8 feet, these flowers make good border plants, but be careful of mildew diseases that attack them.
Asters can be grown indoors or may be sown into the garden directly (providing danger of frost is well past). Plant them in early spring, preparing gardens with a tiller to loosen soil. Sow the seeds approximately 1 foot deep into a mixture of compost and garden soil. Germination usually occurs after approximately 1 month.
Plant in well-drained, moist soil in either partial shade or morning sun. Some varieties can be planted in full sun, but this varies, so be sure to check planting instructions. Compost, peat moss or mulch will retain moisture, control weeds and ensure plants have sufficient nutrients.
Your hole for transplanting asters should be twice as wide and deep as the plant’s container. Plant the crown of the aster even with the ground level. Plant and thin plants to at least 18 inches apart to avoid overcrowding
Caring for Asters
Divide mature plants in spring, just as the new shoots begin to grow. This should be done every few years to avoid crowding of plants.
As with many other flowering plants, dead head (cut back spent flowers) to make room for newer blossoms. This will extend the health and flowering of your plants. Be sure to dead head early on in the blooming season. Blooming will be reduced if done too late. This will also restrain unwanted reseeding which will cause plant overcrowding.
TIP: Our expert gardening advisor, Karen Thurber adds, “To produce a fuller, shorter plant, that requires less staking, pinch your asters when they reach 10 to 12 inches. The first pinch should remove 5 to 6 inches and leave 3to 5 internodes. Asters can be pinched 2to 3 times during the growing season, with your last pinch before July 25th. A pinch later than July 25th will delay flowering.”
Remember, asters are prone to mildew so be careful to plant them in areas with good circulation and good sun exposure.
As with other flowering plants, do not allow water to saturate leaves. Be sure to water at the plant’s roots to prevent mildew and mold. Drip irrigation and utilization of a soaker hose work very well in watering these plants.
In addition to accenting rock gardens, grow your asters in succession, so that have an ongoing blooming season. Planting asters will also deter some insects in your garden. Plant them throughout your garden to limit pesticide use.
Asters attract butterflies, which will enhance the beauty of your garden.
Unlike marigolds and similar plants, aster seedlings are unlike the parent plant and may not be desirable to allow to reproduce. Remove the flower stems before they set seed to prevent this cycle from occurring.
Water asters as directed, but remember that they are considered a “drought tolerant” plant and do not like standing water.
FIRST IMPRESSIONS: Along with the goldenrods and native grasses, asters are the quintessential herbaceous fall color plants of North America. This one is a robust upright perennial with pubescent gray-green leaves. Flowering plants are majestic in fall when crowned with sprays of large starry purple daisies. Plants are tough and adaptable to most moist sunny sites.
HABITAT & HARDINESS: Aster novae-angliae occurs in almost every state or province of North America.
Habitats include moist prairies and meadows, Black Belt prairies, open woodlands, creek or river banks, chalk or clay embankments, roadsides and other disturbed areas.
Plants are hardy from USDA Zones 3-8.
PLANT DESCRIPTION: Aster novae-angliae is a sturdy clump forming perennial with stiff hairy stems.
Leaves are lance shaped, pubescent and up to 4” long. Each leaf clasps the stem and contains two protruding basal lobes.
Large flower heads are arranged in showy panicles. The heads consist of a ring of 40 or more royal purple or pinky-purple ray florets that surround a central cluster of yellow disc florets.
The flowers supply valuable late season nectar for migrating Monarch butterflies. Blooms are also visited by other butterflies, skippers and bees.
Plants grow 3-6’ tall with 2-3’ spread.
CULTURAL & MAINTENANCE NEEDS: Culture is easy in sunny sites with clay, moist well drained soil, or alkaline soil.
Plants tolerate some drought but unattractive or diseased foliage may develop if drought is severe. Plants may also die out in the center if they are not divided periodically.
Aster novae-angliae sometimes has issues with powdery mildew. To prevent the disease give plants good growing conditions and space for air circulation. In gardens, locate this aster in plenty of sun, irrigate during drought and limit overcrowding by using appropriate spacing for companion plants.
Plants can be pruned back to 6” early in the season to control height and promote stronger stems. Cutting should be curtailed by the end of June so that flowers have time to develop. Prune again after flowering if self-seeding is a problem or if foliage is bedraggled.
Plants are fairly unpalatable to browsing deer and rabbits.
LANDSCAPE USES: This is a good choice for a Wildlife Garden, Moist Prairie or Meadow. Plants are also used as Butterfly Nectar Plants or as part of a Grouping or Mass Planting. Aster novae-angliae has Showy Blooms and is appropriate for Cottage Gardens, Deer Resistant Plantings, Water-wise Landscapes, Low Maintenance Plantings, Perennial Borders, Roadsides and Restoration Projects.
COMPANION & UNDERSTUDY PLANTS: Try pairing Aster novae-angliae with Asclepias incarnata, Rudbeckia subtomentosa, Monarda fistulosa, Liatris spicata and Andropogon gerardii..
Aster puniceus would be a suitable replacement due to similar height, flower color and habitat needs. Aster novae-angliae ‘Purple Dome’ could serve as lower growing alternative.
TRIVIA: Many of the established Latin names of Aster spp. were changed recently due to DNA and genetic research findings. So Aster novae-angliae is now known as Symphyotrichum novae-angliae.
Plants host caterpillars of several different moths.
The best identification characteristics of Aster novae-angliae are its pubescent leaves that clasp the stems and its large flower heads that contain more ray florets than most other asters.
The numerous small flowers with their colorful, radically arranged petals are responsible for the fact that the white wood aster belongs to the most attractive late blooms in Central Europe. In late summer and autumn many flowers cover the lush green shrub. Choosing the right location and taking care of it according to the following instructions will ensure that you can enjoy the flowers for several months.
- family: asters (Asteraceae)
- species: asters (asters)
- origin: Europe, Asia, Africa
- perennial, mostly bushy shrub
- growth height: depending on variety 20 to 150 cm
- restant, perennial plant
- flowering period: August to October, rarely until November
- flower color: white, yellow, orange, pink, red, purple, blue
Only when most of the ornamental plants have already faded, the colorful white wood asters have their great appearance. On the small shrubs, numerous colorful and densely growing flowers open up between August and October, which make the plant with a sea of blossoms a real sight. Asters have a very good effect both in the plot, as well as in the stone garden or in buckets. They are also popular as cut flowers in autumn bouquets. So that you have a long time to enjoy the colorful perennial, you should follow the instructions carefully.
In addition to the viewer, insects are also happy about the blossoming splendor: the late-flowering asters serve as a food source for bees and butterflies in the autumn.
White wood asters are comparatively robust, but somewhat more demanding than China asters. With a few measures and a regular care, diseases and pests can be avoided, so that the garden plant thrives and intensively blossoms for many years.
A sunny location is best suited for white wood asters. In the morning and afternoon sun they grow optimally and form a lot of flowers. If possible, however, the shrub plants should not stand in the hot midday sun, as the flowers are not so tolerant and therefore the flowering time can shorten. A few varieties can also be planted in a semi-shady location.
The white wood aster grows optimally in a loose, nutrient-rich, humusible and permeable substrate. Normal garden earth is usually sufficient. If the soil is too sandy, however, it should be mixed with compost. Under too tight ground you can mix sand and / or compost to loosen it and improve its permeability.
In spring or autumn, asters are placed in the ground. A minimum distance of 30 cm should be maintained between the individual perennials. This allows the air to circulate well, resulting in a reduced risk of disease and pest infestation. Young plants, which are still growing strongly, should be put somewhat further. A distance of 50 cm to 80 cm is recommended.
The Aster does not tolerate permanent drought. The soil should always be kept fresh to damp, but without the formation of frost. If it rains too little, the plant must therefore be regularly watered in the summer. Pour the shrub from below and close to the ground so that the leaves do not become moist. White wood asters are prone to mildew, which particularly likes moist leaves.
In order to stimulate the growth and favor a lush bloom, the aster should be fertilized once in the spring. For this purpose, for example, compost can be raked into the ground. Alternatively complete fertilizer is suitable.
Withered flower heads can be carefully removed. This favors the growth of new flowers. If the plant is completely faded, it can be cut back in the upper third. Subsequently, the complete retreat takes place either in late autumn or early spring. All branches and twigs are cut back so that only the base remains.
The white wood aster can be breeded in different ways.
Asters are most easily breeded by division. Every two to four years, a plant should be divided into two or more new plants that you plant separately from each other at a new location. This leads to a rejuvenation, which preserves the flowering ability and strengthens the plant. The division should be carried out after flowering in the late autumn or alternatively at the beginning of the spring. For this, the aster is divided with a sharp and clean knife at the root.
To breed white wood asters over cuttings, first cut a shoot from the mother plant. This should be about ten centimeters long. Remove the foliage in the lower third and insert the shoot into a pot with a potting compost or a mixture of garden soil and sand. As a high humidity favors the growth, you should put a bag or something similar as a hood over the pot.
White wood asters are sown outside in spring. The seeds germinate at temperatures between 18 and 21 degrees Celsius within two to three weeks. If you want to sow asters in summer, autumn or winter, you should do this in a bucket in the house or in the greenhouse. Again, a temperature between 18 and 21 degrees Celsius should be considered. The pre-grown plants can then later be placed outside.
White wood asters are perennial and can overwinter in the bed. In order to protect the roots from frost, the soil can be covered with an additional compost layer around the plant for safety.
The most common disease affecting the perennials is the aster-withering. The following symptoms indicate an attack.
- the leaves suddenly hang limply, dry up and finally die – no matter how much the aster is watered
- the stalks turn brown
- a reddish mucus occurs
The disease is caused by fungus Verticillium, which blocks the plant and prevents it from passing on water. Infested shrubs are no longer to be saved and have to be dug generously as quickly as possible and disposed of in the organic waste collection bin. As the perennial fungals are embedded in the soil, the diseased plant must not be composted. After the aster has been removed, the earth should be mixed with calcium nitrogen. At least eight years later, white wood asters can be planted again at the affected site. Since the fungi only attack asters, other plants can be used here.
In addition, you can use these measures to prevent the aster-withering:
- use stained see
- plant the asters in sterile soil
- change the location of the plants every few years
- divide each aster every three to four years
- use resistant varieties. They can be recognized by the indication “wilted-free”
Care failures often lead to an infestation with powdery mildew. The main threatened are asters, which are constantly moist. The disease manifests itself through various symptoms.
- on the top of the leaf are small white or gray spots
- from the spots develops a mealy covering, which covers leaves, shoots, flowers and buds
- the affected plant parts become brown and fall off
- the plant is more and more stunted
The aster can be saved if the infestation is detected in time. All affected plant parts must be cut off and disposed of in organic waste bin. Subsequently, the plant should be sprayed thoroughly with a fungicide, which acts against mildew.
Preventive measures reduce the risk of infestation:
- the plants should be poured close to the ground and not from above, so that the leaves do not get wet
- those who planted several white wood asters should not put them too close together, as a result, the individual plants are better ventilated and rain, dew and water from other sources dries better
- Asters must not be fertilized too much
Asters are mainly affected by diseases, less by pests. If a pest spreads on the plant, it is usually the aphid like on many other plants. Rinse the small insects with a stinging nettle or soapy solution. The affected plant should be sprayed several times at intervals of two to three days from all sides. Once no aphids are visible, you can complete the treatment.
The white wood aster is a speciose plant, which differs mainly by size, color of the petals and sensitivity. The many varieties can be classified in three different ways.
Bushy aster (Aster dumosus)
The aster dumosus is the lowest type and spreads out strongly to the side. A shrub is between 20 cm and 50 cm high, which is why it is especially suitable for hardwood or as a bedding. It is also a popular cemetery plant. The Aster dumosus produces a particularly large quantity of small flowers.
Among the best known varieties of aster dumosus are:
- the variety bobby-dazzler blooms in the intense Violett and becomes up to 25 cm high
- the aster dumosus rosedwarf develops pink flowers and also reaches a maximum height of 25 cm
- pink to lilac flowers grow on the variety autumn greetings from the Bresserhof, which grows up to 40 cm
- the small white flower of the sort snowpillow reminds of camomile flowers, this aster dumosus reaches a height of maximum 20 cm
New York aster (Aster novi-belgii)
The New York aster differs mainly in its size from the aster dumosus: it achieves a growth height of 50 cm to 150 cm. Larger plants should be supported so that they do not bend. As the name suggests, this aster has smooth leaves. The Aster novi-belgii is more sensitive to diseases than their relatives.
The most popular varieties of this type are:
- the sort beacon is lit in bright pink. It is up to 80 cm tall
- the New York aster Royal Ruby has a full, purple-colored flower and grows up to 60 cm high
- the sort rose quartz has unusually narrow petals in tender pink and is up to 110 cm high
- the blue-violett-blossoming sort beauty of Dietlikon reaches a size of up to 150 cm
New England aster (Aster novae-angliae)
Also up to 150 cm can be the different varieties of the New England aster. This species is distinguished by its hairy leaves. In addition, their flowers close at night and in bad weather. New England asters are more resistant to mildew than other species. However, they tend to discard their leaves in the lower part during flowering. Therefore, the aster novae-angliae often looks bare. However, those who planted lower plants around this species can conceal this easily.
Among the important varieties of New England are:
- the sort Purple Dome has purple flowers and reaches a height of 70 cm
- the Aster novae-angliae Alma Pötschke blooms pink and is up to a meter high
- the only white flowering New England aster is the sort autumn-snow, which grows up to 140 cm
- Ruby treasure is the strong ruby red flowering variety, which is up to 150 cm high
The name Aster comes from a Greek word that means “star”. The flowers heads are star-shaped and resemble the daisy; and come in a variety of colors. This color is displayed in the fall when it is most needed since other flowers begin to fade. The aster plant has about 180 different species in the United States, and with the variety of choices, you can find a plant for almost any garden. There are many uses for this brightly colored flowering plant. Use in borders, rock gardens, or in a special area that has sun to part sun.
Caring for an aster plant is quite easy if you follow a few simple tips and procedures. It is best to plant it in the spring, after the first frost, in well-drained soil that is exposed to full sun to light shade. Even though asters are drought resistant, they need regular watering. Water in the mornings and avoid wetting the leaves since this plant is susceptible to leaf fungus. Fertilize sparingly, and if you want a thick plant with a blanket of blooms, cut stems to half their size in mid-July. This will encourage a bushier plant and more blooms. Once the plant has finished blooming, cut it to the ground and cover with a layer of mulch. The best part of this plant is that it is reliable and comes back year after year. However, it does need to be thinned out every 3-4 years.