Ask a Master Gardener: Bet Your Aster. . .

Symphyotrichum dumosus BUCSA_AdobeStock

By: Melissa Wold, Mobile County Master Gardener, www.mobilecountymastergardeners.org 

you need this plant in your garden.

By now your beautiful spring garden blooms may be fading, drooping and looking downright sorrowful. Don’t despair. Plant asters and watch them steal the fall flower show.

These cold-hardy perennials are pollinator delights from late summer through fall. Growing 1-6 feet tall, depending on variety, these upright plants bloom with star-shaped flowers. Asters derive their name from the Greek word for star (ἀστήρ). Here’s a fun fact for trivia fans: ἀστήρ appears 24 times in the New Testament of the Bible. The flowers range in colors from purple to white to blue.

Over 600 species exist but the most common in our area are New England aster, Symphyotrichum novae-angliae, and New York aster, Symphyotrichum novi-belgii. I also like the Smooth aster, Symphyotrichum lavaeve, and the Blue Woods aster, Symphyotrichum  cordifolium.

Hybrid varieties are grown for showy color. However, native species are a wiser, more ecological choice for gardeners.

New England asters are late bloomers growing 3-6 feet tall. They are well-branched with abundant small, purple flowers. New York asters grow 2-3 feet tall with violet-blue flowers and narrow leaves. The dwarf variety grows 10-15 inches and is a prolific spreader. Smooth asters are mildew-resistant, and love dry, shady areas. Reaching heights of 3-5 feet, their fleshy dark green leaves and purple stems support clusters of sky-blue flowers. Blue Wood asters are shade tolerant, preferring rich humus to produce heart-shaped leaves and grow to 6 feet. Their blooms of small blue flowers last from summer through mid-fall.

Asters are fantastic pollinators. Bees and butterflies flock to these plants. Asters also attract cardinals, finches and other birds to feed on their tasty seed heads. Asters do not attract deer!

These plants are versatile: suitable for borders, rock gardens, wildflower gardens as well as more formal areas. Note that in hot summers, they tend to drop their lower leaves, so you may want to cover their “naked legs” by planting understory plants around them.

Though asters prefer cool, moist summers and cool nights, they grow very well in our southern Alabama’s climate. Avoid planting in direct sunlight. Soil needs to be moist with good drainage and loamy. Wet, clay soil leads to root rot, while dry, sandy soil leads to plant wilt.

Young aster plants should be put in the ground mid-to-late spring after the threat of frost. Mature ones can be planted from late summer to early fall. When planting, space young asters 1-3 feet apart depending on the type and size expectancy. Mature asters should be planted every 3 feet. Water well and mulch. Asters can be grown from seed, but germination can be erratic. If cultivating from seed, plant them in the fall or start them indoors in the winter.

To maintain healthy, vigorous plants, add a thin layer of compost or balanced fertilizer with a 2-inch layer of mulch each spring. Water regularly, but do not overwater. Stake tall varieties to keep them from falling. I admit I let a few of my tall ones droop and run for a whimsical look to the garden. Pinch or cut back asters by one-third once or twice during the summer to promote bushier growth and increased flowering. In winter, asters can be cut back or left to add texture to your winter garden. Divide every 2-3 years.

Asters are a sure bet for your fall garden. Visit the Mobile Botanical Gardens Fall Plant Sale (October 9: 1 p.m.-7 p.m.; October 10 and 11: 9 a.m.-4 p.m.) to buy several varieties of this quaint plant.

Symphyotrichum ericoides Iva_AdobeStock