Ask the Gardener: Mums aren’t the only stars of autumn — these flowers thrive in the fall

Welcome to autumn, fellow gardeners! The days bring cool mornings and pleasant afternoons. A sweet fragrance fills the air as the late-day sun warms the blossoms of goldenrods, asters, gentians, tickseeds, sunflowers, and grasses. Unlike spring and summer blooms, these plants demand patience; we have given them space in our gardens and waited for their time to shine.

Planning for flowers to bloom from April through the end of October can be tricky. Fortunately, many asters and goldenrods grow in a variety of conditions. Beyond their beauty, these flowers provide crucial end-of-season resources for pollinators and seed for migratory and resident birds. I could not imagine a group of plants that fits New England landscapes better. Many species and varieties are available. Here are a few of my favorites.

Goldenrods

Many of you have likely heard this before, but it is worth repeating. Goldenrods do not cause hay fever. Goldenrod pollen is heavy, sticky, and gets moved around by pollinators. The culprit for seasonal allergy sufferers is ragweed. It blooms at the same time as goldenrod, and its pollen is tiny, lightweight, and easily blown into the air.

For dry shade, wreath, also called blue-stemmed goldenrod (Solidago caesia) is a top choice. Growing up to 3 feet, the arching, blue-tinged stems bear clusters of yellow blooms nestled in the leaf axils. Drought-tolerant once established, this goldenrod may seed itself around in the garden, but it can be easily edited as needed.

For shade and slightly moister soils, I recommend zig-zag goldenrod (Solidago flexicaulis). This species features rounded clusters of blooms, also held in the leaf axils, and has rounder leaves with prominent teeth. I have found it quite well-behaved in the garden, with the clumps growing ever larger with each passing season.

For full sun and poor soils (i.e., sandy and rocky), I like how gray goldenrod (Solidago nemoralis) performs. It is among the shortest of the goldenrods, only reaching 2 feet in height and topped with a dense plume of golden blossoms. It spends most of the summer as a tidy clump of grayish-green basal leaves before erupting into bloom in September. The plant spreads slowly via rhizomes or seeds.

My final goldenrod recommendation is a selection of rough goldenrod (Solidago rugosa) called Fireworks. This selection has been on the market for a long time, first discovered in the 1970s and made available to gardeners in the early 1990s. It forms a tidy, bushy clump about 3 feet tall, with overlapping, arching stems covered in yellow flowers; the overall effect is like a firework exploding in your garden. Most importantly, it is not aggressive. Several other goldenrods spread and seed vigorously, and not all suit smaller gardens. They play an important role in supporting wildlife and pollinators, but are best left for abandoned fields, roadsides, and places where ample space balances their exuberance and growth.

Asters

Easily recognized by their cheerful yellow center and spectrum of colorful petals, asters are widely distributed across the United States and heavily represented in New England. Most are very floriferous, from New England aster (Symphyotrichum novae-angliae) with blooms nearly 3 inches across to bushy American aster (Symphyotrichum dumosum) with individual blooms less than an inch in size.

White wood aster (Eurybia divaricata) is common and extremely tough. It thrives in dry shade conditions, growing in woodlands and forests along trailsides and openings. Largely unassuming during the summer months, this aster shines during early autumn with clouds of starry white blooms.

Equally outstanding is heart-leaved aster (Symphyotrichum cordifolium), a stout, branched part-shade denizen that sports dense wands of light blue flowers from mid-September into October. “Avondale” is a popular selection for its slightly smaller stature and long-lasting blooms.

For full sun, I recommend flax-leaf stiff aster (Ionactis linariifolius). This aster has thickened, narrow leaves similar to rosemary in appearance without the fragrance. It is short, reaching only a foot in height, and topped with pale blue blossoms.

Lastly, we have New England aster (Symphyotrichum novae-angliae), a graceful plant with large flowers ranging in color from pink to purple. Characterized by clasping leaf bases and a generally pleasant odor to the foliage when bruised, New England aster could easily be the region’s most recognized wildflower. Breeding efforts have produced several dwarf selections such as Purple Dome and Vibrant Dome, both growing to less than 2 feet in height and spread.

As we look forward to the blazing colors of fall foliage, asters and goldenrods are the perfect complement in the garden. We grow them for their beauty as much as for their ecological significance, and because our autumn landscapes would not be the same without them.

Ulrich Lorimer is the director of horticulture at the Native Plant Trust in Framingham. Send your gardening questions, along with your name/initials and hometown, to [email protected]g.