Aster is a large genus of 250 species of annuals, biennials, perennials, and subshrubs from many different kinds of habitats, mainly in North America. The flowers resemble small daisies, with yellow disk florets, and white, pink, blue, or purple ray florets. The leaves are generally alternate, simple, and lance-shaped. There is an Aster for most any type of garden, including borders, rock gardens, waterside plantings, dry areas, and wildflower gardens.
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. Ranging from 8 inches to almost 8 feet (20 cm to almost 2.4 m), these flowers make good border plants, but be careful of mildew diseases that attack them.
Growing Conditions and General Care
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.
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.
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 (30 cm) 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 (45 cm) apart to avoid overcrowding.
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.