Colorful Autumn-Blooming Plants Can Brighten Up Fall’s Arrival

Last week and this week’s warm and humid weather may possibly be summer’s last uncomfortable gasp. Though many a gardener may have wished otherwise, the quick-to-cool nights signal the fact that it is indeed nearly fall.

I’ve never tried to hide the fact that fall is not my favorite time of the year. I dislike seeing the leaves falling from the trees, the green tomatoes that are doomed to the pickling jar, and the squirrels looking to steal a last cob of corn or newly planted bulb.

There is, however, some comfort to be found in the number of annuals, perennials and shrubs that take fall as their flowering period as well as the many that take this time to rebloom and thus give us a last splash of color before the dull browns of the Hamptons winter set in.

First and foremost are the myriad of hardy chrysanthemums that can brighten up a garden corner and can be beautifully planted in mass drifts or used as specimens. In most cases, they are reliably hardy, can be easily divided every few years and they need not be terribly expensive. In fact, if you are willing to plan your fall garden in the early spring, you can order small mum plants from a mail-order nursery, such as Bluestone Perennials, where an investment of just a few dollars will yield fall flowering plants that are as full and bushy as the most expensive garden center mums that may cost $10 to $15. The other thing to remember is that mums come in forms other than the mounds we buy in pots. These spider, quilled, anemone, pompon, reflex, spoon and seven others are quite different and allow much more creativity. But these are rarely if ever sold in garden centers, so explore online.

Much like the mums, asters have a flowering range from early August through October with a variety of colors and flower dimensions. Heights can range from 1 to 6 feet and the flowers are usually single, semi-double or fully double. Like the mums, asters require plenty of light and a well-drained soil. In their favor (against the mums) is that the asters are not as voracious feeders and several varieties occur naturally on Long Island making it a candidate as a wildflower or native planting.

Ceratostigma plumbaginoides, or the false plumbago, is an excellent groundcover for a sunny location. This is one of the few blue flowers we have available in the fall other than the asters. It’s an excellent rock garden plant, but it starts its spring growth very late and you should be careful not to destroy it inadvertently in your spring cleanup. And since we’re on the subject of rare fall blues, the ageratums are just spectacular this year. One is the perennial ageratum (Eupatorium coelestinum) which is at peak flowering now, and in our garden we have Ageratum houstonianum growing with it and also blooming. The houstonianum is the granddaddy of all annual ageratums and at 18 inches tall, it’s a stunner for the mid-border.

Many of the perennial geraniums (mostly blues) are also reblooming now, adding a colorful touch to the front and edge of the garden. A bit farther back in the border and spotted elsewhere is Verbena bonariensis, an annual, but often self seeding. This plant grows on tall thin spikes and has clusters of lilac to blue flowers that appear to dance above the rest of the garden lasting well into the fall—and they make great cuts.

Then there are the delphiniums. Sending out a second flush of foliage in September, the flower spikes begin to bloom in early October and last for several weeks if permitted. The Montauk daisy (Chrysanthemum nipponicum) flowers in October and can be a magnificent plant if grown correctly. Too many people neglect the early summer pruning of this perennial in which the plant is cut back to stubs ranging from 3 to 8 inches. These stem stubs regenerate new branches, which sport new foliage throughout the summer and the plants remain shorter and more compact than those not pruned and allowed to sprawl. The plant is tolerant to salt spray, wind, low fertility and drought—and yet, thrives and flowers every year even as a short hedge.

Sedum “Autumn Glory” is a succulent that is also drought tolerant and survives even our harshest summers. Atop 1-foot stalks with thick green leaves is a crest of tiny red flowers that creates an influorescence not unlike the achilleas but of a thicker consistency. And don’t forget Sedum “Vera Jameson,” which has almost black foliage and striking pink flowers for about four weeks. Also consider Sedum atropurpurea for foliage and flower color.

The Japanese anemone is often passed by because they bloom after we’ve finished our weekly trips to the garden center earlier in the season, but landscapers and designers know them well and use them often. They offer colors ranging from light pinks to dark reds, white and purple. They’re found under the species japonica and hupehensis and some will bloom up to late October.

On the woody side of things there is Hibiscus syriacus, or the rose of Sharon. This shrub is related to both the perennial hibiscus—which can also flower well into September—and the tropical cousin that you see in greenhouses, seasonal plantings and the warmer climates. They can grow to 15 feet, but seem to do best when heavily pruned in the spring as they flower on new wood only. Originally available only in a lilac purple you can now find a range of colors as well as double flowering varieties and some varieties bloom well into September.

The native shrub Hamamelis virginiana, or the common witch hazel, flowers in October with fragrant yellow blossoms. With a possible height of 20 feet and a spread just as wide, the plant demands a large growing area, but it does like our light soils so long as a good amount of organic matter is added at planting. It’s not easily transplanted, so when buying one make sure it’s been container grown or that is has a large root ball.

There is a woody vine known as Clematis paniculata, or sweet autumn clematis, that you may have noticed climbing an old tree or a fence line with its small but extremely showy white masses of flowers. I marvel at it every fall. It adapts well to tub growth and trellising and it flowers only on new wood—so annual pruning is important. Its sweet fragrance and silvery seed heads are not to go unnoticed either. My trials of the newer varieties that are shorter and not white have been disappointing.

Lastly, don’t overlook the pansies. This viola group, including Viola cornuta, which may rebloom in the spring, has gone through some serious breeding in the last 10 years that has resulted in a range of flower sizes and colors on plants that are both heat and cold tolerant so they do well in September all the way through November. They can be used as filler in borders with blank spaces toward the front and they also look great in planters and pots that need a splash of color and happy faces as we move into the cooler months. Depending on the variety, flowers can be as small as an inch wide up to 2 and 3 inches across.

Let’s spread the color, texture and fragrances well past the traditional blooming season that begins in March and for too many gardens, ends in August. Keep growing.