How to Grow Sweet Peas From Seed

Sweet peas are cool-weather flowers, so timing is everything. They thrive in the mild days of spring and fade once summer heat sets in, which means the goal is to get them growing early while the weather is still cool. In most regions, sow seed outdoors as soon as the soil can be worked in very early spring, four to six weeks before your last expected frost, since young sweet peas tolerate light frost. In mild-winter areas (roughly USDA zones 7 and warmer), you can sow in fall for even earlier, stronger spring bloom. If your springs turn hot quickly, start seeds indoors a few weeks ahead in deep pots and transplant out early. The earlier they establish roots in cool soil, the longer and more generous the flowering season will be.

Sweet peas have a hard seed coat, so give them a head start. The night before sowing, either soak the seeds in room-temperature water for about 12 to 24 hours until they swell, or gently nick the coat opposite the little eye with a nail file. Sow the prepared seeds about one inch deep and two to three inches apart in rich, well-drained soil that gets full sun (afternoon shade helps in hot climates). Because most sweet peas are climbers reaching three to six feet, set up a trellis, netting, or teepee of supports at planting time so the tendrils have something to grab as they rise. Dwarf and bush types need little or no support. Water the bed well after sowing and keep it evenly moist until the seedlings emerge in one to three weeks.

Sweet peas are hungry, thirsty plants that reward steady care. Keep the soil consistently moist but never waterlogged, watering deeply at the base rather than over the foliage. Feed every couple of weeks with a balanced or slightly potassium-rich fertilizer to fuel continuous flowering. When climbing seedlings reach four to six inches tall, pinch out the growing tip just above a leaf pair; this simple step forces bushier, stronger plants with far more flower stems. Keep guiding the vines onto their support and stay ahead of aphids, the one pest that loves sweet peas. Above all, keep picking: the more blooms you harvest, the more the plant produces.

Sweet peas love the company of other cool-season, pollinator-friendly flowers that share their taste for sunshine and rich soil. These non-GMO favorites make lovely bedmates and keep the bees busy:

Sweet peas are one of the best cut flowers you can grow, and cutting them is how you keep them blooming. Harvest stems in the cool of the morning when the lowest one or two flowers on the stem have opened and the rest are still in bud. Use clean scissors and cut long stems, then set them straight into water. Deadhead any faded blooms you do not cut, because if the plant is allowed to form seed pods it will stop flowering and begin to decline. With diligent picking, a healthy patch will keep producing fragrant stems for many weeks until summer heat finally brings the season to a close.

Sweet peas are grown purely for their beauty and their extraordinary scent. They are a classic cottage-garden climber for trellises, arches, fences, and obelisks, and the shorter bush types shine in containers, borders, and window boxes. Above all they are a treasured cut flower: a small handful of stems will perfume a whole room, and their soft, ruffled petals come in nearly every shade from white and cream to pink, lavender, burgundy, and deep violet. They also attract bees and other pollinators to the garden. Note that this is an ornamental flower only, valued for looks and fragrance, and no part of it should ever be eaten.

• Poor or slow germination: the hard seed coat is usually the cause. Soak seeds 12 to 24 hours or nick the coat before sowing, and keep the soil evenly moist until they sprout.
• Plants stop blooming in summer: sweet peas are a cool-season flower and naturally fade in heat. Sow as early as possible, keep them well watered, and enjoy them as a spring crop.
• Few flowers and long leggy vines: usually too little sun or skipped pinching. Grow in full sun and pinch the growing tips early to force bushier, more floriferous plants.
• Aphids clustering on tips and buds: the most common pest. Blast them off with water, encourage ladybugs, or use insecticidal soap early before colonies build.
• Buds dropping before they open (bud drop): often from a sudden cold snap, wide temperature swings, or inconsistent watering. Keep moisture steady and protect from hard late frosts.