Climbing Sweet Pea Vines

Annual Sweet Pea

• Annual sweet pea, native it Italy, Sicily and the Greek island of Crete, grows as a 3- to-8-foot climber or mounding, 30-inch bush. While it grows as a perennial in U.S. Department of Agriculture Plant Hardiness Zones 9 and 10, it dies at temperatures below 20 degrees Fahrenheit. Gardeners also have trouble growing the annual where temperatures exceed 86 degrees more than 120 days a year. The vines respond to cool climates with spring-to-fall blooms in every color but yellow.

Perennial Sweet Pea

• Native to every state but Hawaii and Alaska, perennial sweet pea vines vines climb from 5 to 7 feet. Allowed to sprawl, they form erosion-controlling, ground-covering mats from 1 1/2 to 2 1/2 feet deep. Their unscented flowers, in white, pink or purple, resemble those of annual vines. The blooms open against tendrils of ferny green foliage from June until August. They give way to flat, dark gray or black seed pods.

Cultivars

• L. odorata "Cupani" takes its name from the Italian monk who, tradition has it, developed the cultivar in the 1600s. The 4- to 6-foot vine's tri-colored blooms have a dark, red-violet upper petal, blue-purple central petals and a deep purple lower petal, or keel. "Lancer," the only commercially produced L. latifolia cultivar, was a 1984 introduction from the USDA and the Michigan Department of Transportation. Used as a roadside ground cover, the vine stands 2 to 3 feet high. Lancer produces dense clusters of white or purple flowers for up to six weeks each summer. It performs best across the Northeastern and Great Lakes states.

Growing Sweet Peas

• The formula for successfully growing sweet pea vines includes cool springs and summers, full sun, fertile soil high in organic material, regularly spaced fertilizer applications and consistent moisture. Starting plants indoors from seed during the winter and planting the seedlings in early spring works best where summers are hot. In mild winter climates, annual sweet pea vines bloom in late winter and early spring from directly sown seeds. Perennial vines require direct seeding in sunny sites with moist, neutral-to-alkaline soils. Add lime to soil with a pH reading lower than 5.0 before planting the seeds.