Asters are the colorful stars of fall gardens

The most colorful flowers in our garden right now are asters. Their blossoms are not only decorative but provide late-season nutrition for native pollinators and butterflies.

These are cultivars of asters native to North America, although genetic research in the 1990s changed their classification so today they may be listed as Symphiotrichum or Eurybia. Whatever they’re called, asters are a mainstay of autumn gardens since their long period of flower provides color from late August until frost.

Most asters need full sun and thrive in ordinary garden soil. They’re resistant to juglone, the toxin that’s released by walnut trees, and are said to be rabbit resistant. In my experience, however, the rabbit resistance is confined to late summer New England asters. The rabbits in our garden have feasted on all of our asters early in the summer when the leaves are tender.

We’ve had lots of asters in our garden, although I’ve had the most success with one that’s shade tolerant and has tiny flowers. Big-leaf aster (Eurybia macrophylla) is a mainstay of our small woodland bed, where they grow interspersed with Zig-zag goldenrod and mayapples. The aster appears in spring with a basal disc of slightly hairy, heart-shaped leaves. In the autumn the plant produces flat sprays of small lavender-white flowers that are favorites of small native pollinators. It’s only about 6 inches tall and requires absolutely no care from us. That’s probably why it’s also one of my favorite flowers.

Over the years I’ve also tried calico aster ‘Lady in Black’ (Symphiotrichum laterifolium), which is a a large plant with dark purple leaves. Unfortunately, the rabbits enjoyed eating it as soon as it popped out of the ground.        

The local rabbits also gobbled down every New York aster I’ve tried. Short ‘Hein Richard’ (S. novi-belgii) barely made it out of the ground and ‘Professor Kippenburg’ didn’t fare much better even when I put protection around it.

New England asters (S. novae-angliae) have fared much better. They have woody stems and slightly hairy leaves so the rabbits only nibble on them early when there’s not much else to eat. That means a few inches of bare stem at the bottom of the plant and slightly shorter plants, which isn’t a bad thing since gardeners cut back many kinds of asters in the summer. The asters don’t seem to mind and I’m happy to let the rabbits do this job for me.

My favorite New England aster is ‘Purple Dome.’ It’s a compact 24 inches tall and, as its name suggests, it forms a dome of neon purple flowers in late September. The flowers are semi-double so they make a bolder display than many asters. There’s now a bright pink form, ‘Vibrant Dome.’ Before that I used ‘Alert’ for pink autumn color, but the flowers on it and the red New England aster ‘September Ruby’ are single and don’t produce the same pops of color as the Domes do.

In humid summers like this one, asters may have issues with powdery mildew and botrytis blight, both fungal diseases. Good fall sanitation can fight both. A biological fungicide, Mycostop, can also be helpful if applied when the asters come out of the soil in the spring.