Garden nurtured by an adventurous green thumb

MARGE HOLS

Visiting Joan Duddingston's St. Paul garden is like embarking on a treasure hunt. You are sure to discover delectable plants you've never seen before.

I've come to think of Duddingston, a good friend, as "The Adventuresome Gardener." It isn't just the deutzia shrubs by the front garden gate or the flowering quince and oakleaf hydrangea nearby. It's the cotton patch in the middle of her backyard cutting garden.

"A sturdy stalk comes out of the ground and pretty tri-lobed, light-green leaves grow," says Duddingston, an astute observer. "The blossoms are a lovely cream. They look like a poppy, but sturdier, and they're tucked down into the branch crotches. The interesting thing is each flower lasts just one day; it closes at night and turns pink. There are lots of cotton bolls coming along."

Duddingston, a member of the St. Paul Garden Club, starts many of her plants from seed indoors under shop lights. She discovered cotton seeds in this year's Pinetree Garden Seeds catalog.

"I thought, 'Oh, well, why don't I see what happens?' " Duddingston said. "I had seen flowers in a cotton field down South. They looked quite pretty, but I couldn't get close to them. It would be fun to have cotton, too, but I don't know if we have a long enough growing season for the bolls to ripen."

Duddingston's curiosity drives the plant choices in her spacious, colorful garden on Summit Avenue. She likes to try new plants each year and enjoys the challenge of trial and error.

"I'm a restless gardener," she says. "I learn so much every year. By fall, I have 13 ideas of what I'm going to do differently."

Shrubs that aren't supposed to be hardy here are a favorite challenge. Most are labeled as hardy in Zone 5 rather than our colder Zone 4. Often, they die almost to the ground over winter, but then struggle back.

"I thought my 'Snow Queen' oakleaf hydrangea died last winter, but it decided to come back again," Duddingston says of a handsome, mounded shrub with dark-green, oaklike leaves. "I've had it three years, and have had one blossom, maybe two, because it can just barely make it." Foliage turns a rich burgundy in fall.

A 'Golden Plume' elder Duddingston thought was a goner this spring also has emerged anew. Its golden, cutleaf foliage is striking against the black iron fence that contains the garden.

Variegated Japanese pieris is a spring-blooming shrub I've seen only in Duddingston's garden. New reddish foliage is almost showier than tiny cream flowers on panicles that arch like a waterfall. Duddingston says she doesn't mind that the shrub, after dying back, reverted from variegated to green foliage; she's just glad it's alive.

A flowering quince poses the opposite problem, growing much larger than advertised. Although it displays beautiful, peachy rose blossoms in spring, Duddingston says flowers aren't showy enough to compensate for the effort it takes to hack back the shrub every year.

"There are so many plants to choose from," she says. "I'll probably send away for something to replace it. I send for things because you can get the plant and color you want."

Other favorite woody plants in the garden are the deutzias with spires of delicate little white flowers in June, 'Pink Spires' summersweet, 'Mohawk' viburnum with red buds and white snowball flowers and 'Gouchaultii' dogwood with mottled lime-on-green foliage. A Japanese maple has cut leaves that turn peachy red in spring, green in summer and brilliant red in fall.

Duddingston's adventures in plants extend to perennials, too. There's a burnet (Sanguisorba) with pink bottlebrush flowers, the new variegated 'Stairway to Heaven' Jacob's ladder, a delectable 'Hort's Variety' peach-colored Lychnis and a double-petal Rudbeckia hirta 'Gloriosa Double Gold.'

To illuminate corners of her garden, Duddingston uses plants with golden foliage. 'Gold Heart' bleeding heart and new 'Tiger Eyes' golden sumac are favorites. To screen the driveway, she's growing a climbing hydrangea with big, creamy flowers on her fence.

Duddingston admires a hibiscus that showed up in her garden unbidden last year. She has identified it as Hibiscus trionum, a Victorian-era annual seldom seen today. A shrubby plant, it has 2-inch creamy flowers with dark brown centers. She collected seeds and planted it again this year.

Vigorous, oh so healthy, tea roses bloom all along a low brick wall in the front garden. Duddingston's favorite is 'Mellow Yellow' because, unlike most yellow tea roses, flowers hold their petals for days in the garden or in a vase. Duddingston digs in a slow-release fertilizer around each rose bush in spring. She removes diseased leaves and sprays only if she sees a problem. To prepare each rose for winter, she cuts canes back to about one foot, encircles the bush with 12-inch green garden fencing and packs in leaf mulch.

A fastidious gardener, Duddingston coaxes a second bloom from many plants by cutting them back after they bloom.

"I'm a terrible chopper," Duddingston says. "You can see how floriferous plants are when you shear them." Perennials that rebloom after a haircut include Lychnis, coreopsis 'Moonbeam,' dianthus, globe flower and mullein. Annuals include calendula, cosmos, lavatera, sweet scabious and flowering tobacco.

As I leave the garden, I store nuggets Duddingston has shared: For early-summer blooms, start dahlias indoors in mid-March because they require 90 days to bloom. And plant tuberous begonias so pointed ends of the leaves face the way you want the flowers to show.

Marge Hols is a Master Gardener with the University of Minnesota Extension Service. You can contact her at dmhols@comcast.net.

This week's checklist

• Water your evergreen trees and shrubs weekly until the ground freezes to prepare them for winter. Because evergreens transpire all winter, they need extra moisture.

• Haul large houseplants outside and wash foliage with a hose.

• Recycle black plastic pots this weekend or next by bringing them to a drop-off site. Black pots of any size will be accepted, but no colored pots. Drop-off sites