By Marty Ross

Universal Uclick

With a flash and a flourish, chrysanthemums signal the transition to a new season. Even the fiery foliage of a maple tree can’t match the gorgeous colors of mums.

Garden shops go all-out for the mum season.

“By the time we’ve had a typical summer, the garden is starting to have some holes, other things in the garden are going downhill and gardeners are ready for fall. They’re ready to buy mums,” says Tony Fulmer, horticulturist at Chalet Nursery in Wilmette, Illinois, near Chicago. The shop sells thousands of mums from early September through October. “People buy them for their window boxes, for pots on the front porch, for flower beds and for parties.”

Putting mums to work in a garden is easy. They are vigorous plants, ready to burst into bloom when they arrive at garden shops in fall. You can plop them into a planter box, display them in pots on straw bales or set small pots of mums in a row down the middle of a patio table. Chrysanthemums naturally come into bloom when the days grow shorter in fall, and it is as if they are taking advantage of the softer autumn light. Mums seem to glow in a garden, no matter where you put them.

Mums grow best in sunny spots, but they tolerate a surprising amount of shade, so tucking a couple of plants up on the porch or on a shady deck or patio is just fine. No gardening experience is necessary: Mums need to be watered, of course, but the producers deliver plants that need little attention. If you buy plants just as the buds are beginning to open, you can count on about six weeks of bloom.

Most gardeners treat mums as annual flowers, growing them for one season only and tossing them on the compost pile after they fade. They aren’t really annuals, however; they are perennial plants that could live in the garden for years, but the season itself presents challenges to their survival. Mums planted in the garden in fall usually do not have quite enough time to establish good root systems, especially if they are kept in artfully placed pots through most of the fall. If plants set out in the garden are not watered well during the fall, and mulched, winter often kills them.

Even botanic gardens treat mums as annuals. Tim Pollack, a horticulturist at the Chicago Botanic Garden, has been growing mums for 20 years and has worked on the garden’s spectacular fall display of mums for 13 years. Visitors arriving at the garden encounter 10-foot-tall towers of mums, each made up of more than 250 plants. Once inside the garden’s gates, the main path leads across a covered bridge festooned with cascading mums. Giant pots of mums in the garden are planted with up to 70 plants each. More than 12,000 mums are on display — it’s a horticultural show on a grand scale, requiring months of preparation. They’re all grown from cuttings every year, starting in February.

Although mums have been around for many years, the plants sold today are bigger and better than mums of the past, Pollack says. “They have introduced new flower colors, and the plants are more round and longer-lasting,” he says. “In the old days, the majority of the cultivars were mid-season blooming, but now they really extend the season,” he says, which pleases both gardeners and retailers.

Ideally, gardeners should purchase mums when no more than one fourth of the buds are open. “We try not to install any of our displays with open flowers,” Pollack says, so returning visitors can have the pleasure of seeing the fantastic display come into full bloom. To keep them at their best, the gardeners continue to fertilize lightly while the plants are blooming, and they keep up the watering routine the plants had been accustomed to as they developed through the summer in the greenhouse.

 Igloo mums planted in a garden (there are 11 of them in the series, with names like Pumpkin Igloo and Fireworks Igloo) can tolerate bone-chilling temperatures, and they are catching on particularly with cold-climate gardeners who want mums to fill a spot in their flower beds all year round, says Bill Aulenbach of Blooms of Bressingham.

Whether you grow mums as annuals or perennials, this is their season to shine. “These are grab-and-go plants,” Fulmer says. “With a sharp shovel and 15 minutes, you can make a big splash.”