How to Grow Sweet Pea
Annual
Sweet pea (Lathyrus odoratus) is a cool-season climbing annual grown for its ruffled, richly colored flowers and its old-fashioned, honey-sweet fragrance. US home gardeners plant it on fences, trellises, and arbors, and it is one of the most popular flowers for backyard cutting gardens. The blooms come in nearly every shade except true yellow, and many heirloom types are prized above all for their scent.
Planting
Sweet peas grow best when planted early while the weather is still cool, so direct sow seeds outdoors as soon as the soil can be worked in late winter or early spring, often 4 to 6 weeks before your last expected frost. In mild-winter regions of the South and West (roughly USDA zones 7 and warmer), you can also sow in fall for earlier, stronger spring plants. Choose a spot in full sun with rich, loose, well-drained soil that has been worked deeply and generously amended with compost, and set seeds about 1 inch deep and 4 to 6 inches apart at the base of a trellis or other support. Soaking the seeds in water overnight before planting helps them sprout more evenly.
Care
Keep the soil consistently moist but never waterlogged, watering deeply at the base of the plants rather than overhead, especially once buds begin to form. Sweet peas are heavy feeders, so work plenty of compost into the bed before planting and side-dress with additional compost as the vines climb. Pinch out the growing tips when seedlings are 4 to 6 inches tall to encourage bushier plants, and pick or deadhead flowers often, because leaving spent blooms to form seed pods will quickly stop production. Provide netting, string, or a trellis for the tendrils to climb, and gently guide the young vines onto their support; as summer heat arrives the plants naturally decline and can be pulled and composted.
Bloom time
Sweet peas bloom from mid-spring into early summer, and in cooler climates they can flower for many weeks. Hot weather ends the show, so the display is generally shorter where summers turn warm quickly.
Garden uses
Sweet peas are outstanding cut flowers, filling vases and small bouquets with color and fragrance, and they attract bees and other pollinators. Their climbing habit also makes them ideal for dressing up fences, trellises, arbors, and large containers with a support.
Tips
The single best thing you can do is plant early and pick often, since sweet peas thrive in cool weather and keep blooming only if flowers are cut before they set seed. Choose heirloom or fragrant varieties if scent is your goal, because some modern large-flowered types trade fragrance for size. In hot-summer areas, site the plants where their roots stay cool and shaded and mulch the bed to stretch the flowering season a little longer.
General guidance for US gardens. Timing and hardiness vary by region; check your local frost dates and hardiness zone. Page updated Aug 4, 2026.