Asters: Heroes of the Fall Garden

By David Salman, High Country Gardens Chief Horticulturist

Asters are a huge genus of wildflowers native all across the northern hemisphere, including North American, Europe, and Asia. For thousands of years, these flowers were called Asters around the globe, derived from the Greek word for 'star'. Recently, North American Asters were re-named with the botanical name Symphyotrichum, to differentiate them from European and Asian Asters. 

Here in North America, our native species and improved native selections of Asters are late-summer and fall bloomers. This makes them an integral part of the food chain for native bees, honeybees, butterflies, and migrating Monarchs. Their late-season blooms are an essential food source for some of our favorite pollinators as they fuel up for winter hibernation or winter migration. They also provide late-season color, keeping our gardens and landscapes beautiful and interesting well through fall. You can even leave them standing for early winter interest.

There are many fine species, selections, and hybrids from Europe and Asia, but these tend to be spring and early summer bloomers.

Outstanding native Asters are often overlooked when gardeners shop for perennial flowers. Perhaps it's because they aren't in bloom in the spring when many folks do their flower shopping. But I can say with confidence that the late-season Asters are worth seeking out for their easy-to-grow nature, their beauty in bloom, and their essential role in habitat creation for pollinators.

Asters are at home in both natural meadow-style plantings and perennial borders. Planted in large swaths, they can create a pollinator buffet that makes fueling up for fall easy for flying friends. 

Asters are available in a wide range of sizes, heights, and forms, so there's an Aster suitable for every garden. These perennials require very little effort on the part of gardeners. It's as easy as one, two, three. 

1. Plant them in full sun. (Some varieties can tolerate partial shade)
2. Plant them in average to less-than-ideal soils. Average garden loam, clay, and sandy soils are all good. Avoid wet soil locations and stay away from overly rich, heavily composted soils.
3. Give them modestly amended soil (a handful of Yum Yum Mix and good quality compost at planting time) and regular watering to get them established the first growing season.

• Leave them standing over the winter months and cut back the stems to just a couple of inches above the crown in mid-spring.
• Fertilize in the fall. Don't use chemical fertilizers on Asters (or any other garden plants for that matter). Use Yum Yum Mix (or the equivalent) which is actually what I call a "soil food". Yum Yum Mix is a blend of nutrients that feed the soil microbes, beneficial soil fungi, and earthworms necessary for healthy living soil. The soil "digests" these nutrients leaving behind the nitrogen, phosphorus, potassium, and trace elements that the plants need to thrive.
• Go easy on the water and fertilizer. Asters grow best with "tough love". Come the second growing season, back off, and let them take care of themselves with a minimum of care.
• Go easy on the mulch. Many plant-derived mulch materials like coarse compost, composted leaves, and composted bark enrich the soil over time as they break down. Thrifty growers like Asters don't like or need rich soil, so these soil building mulches should not be used on Asters. Leave them un-mulched in moderate climates. In harsh, dry conditions, use pine needles or crushed gravel.

• Bluebird Smooth Aster (Aster laevis 'Bluebird') is one of the very best of our native Asters, providing a profusion of 1-inch violet-blue flowers held in clusters at the tips of the growing stems. Attractive blue-green foliage provides garden interest prior to the showy flowers. 'Bluebird' was introduced by Dr. Richard Lightly of the Mt. Cuba Center Botanical Gardens where it was rated as the #1 performing Aster in their garden evaluation of the genus.
• Raydon's Favorite' Aster (Aster oblongifolius) is one of our most reliable native perennial Asters. It has a strikingly beautiful mounded appearance with attractive foliage. Blooming in mid-to-late fall, it displays large clusters of blue-purple, daisy-like flowers on a 2-3 ft. tall multi-stemmed plant. Vigorous and unfussy in the garden, 'Raydon's Favorite' Aster grows in rocky, loam and clay soils and withstands difficult growing conditions very well. It was a top-rated selection in the Chicago Botanic Garden trials, exhibiting exceptional flower production and outstanding winter hardiness. In cultivation for many years, it can be considered an heirloom plant and was introduced into cultivation by San Antonio gardener Raydon Alexander, who got it in the wilds of Tennessee.

• Purple Dome New England Aster (Aster novae-angliae 'Purple Dome') This selection of New England Aster is notable for its tidy, compact, mounding habit and luscious deep lavender-purple flowers. Sometimes affected by mildew in humid climates, it has been a star in the arid western US where the foliage stays "clean and green."
• Lady In Black Aster (Aster lateriflorus 'Lady in Black')- Grow this native perennial Aster for its very attractive purplish-black foliage and clouds of small rose-red centered white daisies. Blooming in late summer and early fall, 'Lady in Black' is an easy-to-grow perennial that thrives in a variety of soil and climatic conditions. The plant received a top 5-star rating in the Chicago Botanic Garden's extensive six-year evaluation of asters.

We offer a broad range of Asters with varying flower colors, heights, and preferred growing conditions. To find the right Aster for your garden, you can use the filters on our shopping page to find the best fit.