One of the most colorful flowers of fall is also September’s birth flower, the aster (Symphyotrichum spp.), sometimes referred to as the starwort or frost flower.

The aster, which belongs to the daisy family, is a perennial with more than 600 species.

Formerly wildflowers, asters are seen in many colors ranging from white to orange but commonly have pink, white, red, mauve or lilac blooms.

Asters are symbols of all-powerful love, affection and wisdom. They have also been known to represent valor, purity, innocence, royalty and faith.

Different aster colors can also convey different meanings:

- Purple represents wisdom and royalty. Within European civilizations, members of royal families wore purple to signify their nobility.

- White symbolizes purity, innocence and new beginnings.

Red and pink asters mean undying devotion.

Despite its appearance, the aster flower is not one large single flower, but a collection of many tiny tubular flowers.

They are a favorite of butterflies.

For planting, choose a site with full to partial sun. Soil should be moist and loamy with good drainage. Mix in compost prior to planting.

Plant one to three feet apart depending on their anticipated mature size. Light fertilizer applied early in the season can benefit the plantings.

Asters can be grown from seed, but germination may be uneven.

Fully-grown, potted asters may be planted whenever they become available.

Give plants plenty of water at the time of planting.

Add mulch to keep soil cool and prevent weeds. A thin layer of compost or balanced fertilizer with a two-inch layer of mulch added around the plants every spring will encourage vigorous growth.

Water plants regularly during the summer. However, many asters are moisture-sensitive. If your plants have too much or too little moisture, they will often lose their lower foliage or not flower well. Watch for stressed plants and try a different watering method if your plants are losing flowers.

Asters range in bloom time from early September to late October, with a particular species or cultivar usually blooming for two or three weeks.

Asters are sensitive to powdery mildew, rusts, white smut, leaf spots, stem cankers, aphids, mites, slugs, snails and nematodes. The main plant disease is a powdery whitish growth that may appear on leaves from late June or July onwards.

They are versatile and can be used in borders, rock gardens, wildflower gardens and other landscapes. Depending on the variety, the plant’s height can range from eight inches to eight feet, so there are asters suitable for every garden.

Pinch back asters a few times in the early summer to promote bushier growth and more blooms. Aster flowers that mature fully may reseed themselves but resulting flowers may not bloom true, meaning you may not get the same color flower that you originally planted.

Divide every two to three years in the spring to maintain your plant’s vigor and flower quality.

Cut asters back in winter after the foliage has died or leave them through the winter to add off-season interest to your garden.

Asters add color to the late summer and early fall garden when many summer blooms are fading. They also complement the rich colors of fall mums.

Asters work well as cut flowers and make attractive fall arrangements. And don’t forget bouquets of asters for September birthdays!

“Growing Green” is contributed by Diane Dorn, Lehigh County Extension Office Staff, and Master Gardeners. Information: Lehigh County Extension Office, 610-391-9840; Northampton County Extension Office, 610-813-6613