Spring Training for Vines

Passionflower Blue Bouquet.
Passionflower Blue Bouquet. (Logee's Greenhouses)
By Adrian Higgins
Washington Post Staff Writer
Thursday, March 8, 2007

Spring arrives in two weeks, officially, but if past is prologue, the first string of balmy days will be here before that to warm the blood. In early March, the garden centers begin to stock up with the bright plants of the pre-season in anticipation of the fever.

Rushing out to buy pansies or primroses is a fine way to celebrate winter's end, but if you really want to do something for the garden now, think about choosing the annual and tender vines that will drape and decorate that far-off world of the late-summer garden.

Why vines? They make up one of the few groups of plants that grow happily in a pot and rapidly enough in one season to provide near instant screening on a trellis or arbor, deck railing, wire fence, mailbox or lamppost.

Common climbers, such as morning glories, or less-well-known ones, such as the weirdly flowered aristolochias, are particularly useful for screening in city gardens and apartment balconies too small to support trees and shrubs. A decorative trellis forms an ideal support for these vines. Some, including passionflowers and the hyacinth bean vine, may be tender in name but can produce some serious biomass come October. If you need to build or install a sturdy trellis, do it now.

These annual vines have a place in larger landscapes as well, grown as patio plants or on supports in garden beds to provide late-season color, height and focus. March is the month to seek them out. One of the complaints about seed-sown morning glories -- fleeting trumpet flowers in shades of blue, purple, red and white -- is that they are slow to flower, blooming as late as September. This is an ingrained trait; they flower in response to summer's shortening days. But other factors contribute to the tardiness.

April is too soon to sow them, but June is too late. So pick May. Hasten germination by soaking the seeds in tepid water overnight before sowing. And plant them where they will get lots of afternoon sunlight. Don't give them a high nitrogen feed or place them in too rich a soil. Those factors will promote vigorous growth but few flowers.

Renee Shepherd, founder of the online seed nursery Renee's Garden, says varieties of morning glories named purpurea and tricolor will flower earlier than others. These include Heavenly Blue, Early Call, the heirloom Grandpa Ott's and a variety put together by Shepherd called Mailbox Mix, with flowers in blue and white.

The family also includes the gorgeous scented moonflower vine, whose big, fragrant trumpets open at night. The cardinal vine, another relative, has tiny scarlet trumpets that draw hummingbirds. No late summer is complete without either. An obscure tropical vine named momordica is seed-sown in May, will cover a tall trellis by late summer and eventually will produce edible fruit. The Thomas Jefferson Center for Historic Plants in Charlottesville sells two varieties, the balsam pear and the balsam apple.

Byron Martin of Logee's Greenhouses in Danielson, Conn., favors a morning glory named Blue Dawn Flower. Its vigor has made it a weed in some tropical regions, but for Washington gardeners it is simply a vine for a lot of summer coverage. Martin said the flowers stay open longer than typical morning glories, whose blooms shrivel in the heat of the day, to be replaced with new ones the following night.

Martin also recommends a thunbergia hybrid named Sunlady. "You can put it in as a young cutting and it will take over a trellis by the end of the season," he said. Its single flowers are daisylike, with pale yellow petals and a black center.

Logee's sells almost 30 varieties of passionflower; some grow vigorously in one season for annual effect. Two or three are hardy in Washington, notably the Maypop and Incense, but if you limit yourself to those you will miss some extraordinary varieties. Among the fast-growing annual types, Martin suggests Blue Bouquet, loaded with the passionflower's distinctive exotic-looking and botanically complex flower. He also recommends Blue-Eyed Susan, a passionflower variety that is richly purple with heavily feathered filaments and, at four inches across, big.

Star of Surbiton is an English hybrid, blushed white, with a corolla ringed in pink, white and lavender. Star of Clevedon has narrow white petals and a lavender corolla. If you grow vines in pots and have a cool, dry storage place for the winter, you can venture into other passionflower varieties that need some age to put on a big show. Just cut them back in October and bring the pots inside. I love the tender red flowering ones, particularly Ruby Glow.

The adventurous gardener might try the snail bean, Vigna caracalla. Jefferson raised it at Monticello and probably delighted in its coiled white and purple flowers, late to appear in the season but heavily scented. It will grow 10 feet by September and is a fairly heavy feeder. Keep the tuber in a pot to prevent the taproot from going deep, so that it can be lifted in October. Cut it back and keep it dry and dormant indoors as you would a dahlia.

The tender vine aristolochia is sometimes named Dutchman's Pipes because of the shape of some varieties. However, the bloom of the Aristolochia grandiflora is a huge disk mottled in cream and burgundy. The description in Logee's catalogue seems to have been written by Jules Verne: "Upon closer inspection, you are carried through a yawning mouth which leads to an inflated pouch." The Aristolochia gigantea Brasiliensis is even more bizarre. The flaccid bloom hangs like a flag, almost 12 inches deep. "One of the most outrageous flowers in the world," said Martin. Sounds great for sultry August nights.

Several vining annuals produce food for the table. Shepherd sells a gourd mix she calls Wings and Warts for the shape of the various fruit. She also suggests an Italian climbing summer squash named Trombetta, which could be interplanted with a fall fruiting dwarf pumpkin named Mini Jack. This is my kind of spring fever.

Logee's Greenhouses: 888-330-8038,http://www.logees.com. Renee's Garden, 888-880-7228,http://www.reneesgarden.com. Thomas Jefferson Center for Historic Plants, 800-243-1743,http://www.twinleaf.org.

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