Warm fall hues of chrysanthemums and asters will soon brighten the aisles of local garden centers. As summer gardens begin to fade, these trusty autumn bloomers offer a vibrant splash of color — perfect for reviving landscapes or patio containers and extending seasonal beauty well into the cooler months.
Mums and asters naturally begin to bloom as daylight shortens in late summer to early fall. As short-day plants, they rely on longer nights to trigger their flower buds. To help them thrive, plant them in a spot that receives full sun or light shade, and ensure the soil is well-drained.
Chrysanthemums (Mums)
Chrysanthemums typically grow between 2 to 4 feet tall in garden settings. With thousands of cultivars available commercially, they offer a stunning variety of heights, flower sizes, shapes, and colors. From vibrant yellows and oranges to rich reds, purples, soft pinks, and crisp whites, mums bring a dynamic and colorful presence to any fall garden.
Mums are ideally planted in the spring with other garden perennials; however, fall planting is also possible, just be sure to plant them at least six weeks before the first expected frost to allow roots to develop. Because mums are shallow-rooted, they require frequent watering during hot, dry spells to stay healthy. Keep in mind that blooming mums planted in the fall may struggle to survive winter, as their energy is focused on flowering rather than root growth. Once blooming has finished and a hard frost has killed the foliage, cut the plant back to ground level and apply a light layer of mulch. This helps insulate the roots and protect the plant from harsh winter temperatures.
Asters
Asters also bring a burst of late-season color, with over 180 species, several of which are native to Illinois. Two popular and easy-to-find varieties are New England aster (Symphyotrichum novae-angliae) and aromatic aster (Symphyotrichum oblongifolium). Their delicate, daisy-like blooms come in vibrant shades of purple, white, pink, and red, each accented by a cheerful yellow center. Don’t be alarmed if the lower leaves turn brown and dry out during peak bloom — this is a normal part of the plant’s growth cycle.
Asters are typically hardy perennials in Illinois gardens, but to overwinter successfully, they should be planted at least six weeks before the ground freezes. This allows time for their root systems to establish before wintry weather sets in. Varieties range widely in height, from compact six-inch types to towering six-foot specimens. For taller varieties, pruning back by one-third several times during the summer (ending in mid-July) helps create a more compact, bushier plant. This practice not only improves form but also encourages a greater number of blooms.
To prevent asters from self-seeding throughout your garden, cut back the plant to about two inches above ground level after the first hard frost has turned the foliage brown. You can also choose to leave the plant and developing seeds for winter interest and for the birds to enjoy.
Pollinator-Friendly Fall Color
This fall, when you visit the garden center in search of seasonal color, be sure to toss a mum or aster into your cart. These vibrant bloomers will add a splash of autumnal charm to your home landscape and keep your garden gorgeous for a couple more months!
Fall favorites of bees and butterflies, mums and asters, are a reliable source of fall nectar for pollinators that are traveling on their fall migration. While most flowers have already finished blooming, these two are just starting their show in the garden. Asters also serve as the larval host plant for several butterflies and moths, including painted lady butterflies.
About the Author
Brittnay Haag is a Horticulture Educator with University of Illinois Extension, serving Livingston, McLean, and Woodford Counties. Her work focuses on youth horticulture education, specifically through school gardens and Jr. Master Gardener programs.