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Celebrate Sweet Peas
by Charlotte Kidd
by Charlotte Kidd

email: charlottekidd@comcast.net

Charlotte Kidd, M. Ed., is the owner of In The Garden Design, Care & Workshops in Flourtown, PA.

An organic gardener since the 1970s, she brings environmentally harmonious techniques to ornamental gardens in Southeastern Pennsylvania. She's studied horticulture at Temple University and Longwood Gardens and teaches at the Morris Arboretum of the University of Pennsylvania and the Main Line School Night.

Charlotte is a member of the Garden Writers Association and the Society of Environmental Journalists.

Charlotte gardens in Zone 6b.


April 20, 2014

Twining post, trellis, and fence, colorful sweet peas bring an old-fashioned charm to any garden. Fragrant with wavy petals, the sweet pea is at home in the cottage garden and as an elegant cut flower at a formal table. With new shorter, tendril-free varieties such as 'Explorer' and 'Cupid', sweet peas cascade from windowboxes and softly edge sculptural containers.

If you've admired these celebraties from afar, why not give them a try? Spring chill is ideal for sweet peas; summer heat's best for melons - a future column. So now's the time to be thinking about the Lathyrus species - Lathyrus odoratus is the botanical name for the annual sweet pea. The lovely cold hardy perennial form is Lathyrus latifolius, suitable to USDA Zone 5.

Note Bene: Annual flowery Lathyrus odoratus is poisonous, so don't confuse it with edible garden peas (Pisum sativum).

The sweet pea, among the earliest flowering annuals, is easy to grow from seed either outdoors or indoors depending on soil temperature. Relatively cold hardy, the plant won't mind spring frost but could be killed by hard freeze. Sweet pea seed will germinate in soil that's 55° to 65° F. Note, that's soil temperature, not air temperature. To bloom, sweet peas need about 50 days of cool temperatures (under 60°F). They prefer rich, loamy, moist but well-drained soil in full to part sun.

Outdoor Sowing

Plant sweet peas outdoors as soon as the soil is workable - about 6 weeks before the last frost. That means mid to late March as we in the Philadelphia area (USDA Zone 6) count Mother's Day as the last frost date. Make several plantings over several weeks to extend bloom time. Watch for sprouts in about 10 to 21 days. Be sure to protect the planting area with a light rowcover to keep birds, squirrels, and rabbits from digging up seeds and nibbling tender shoots.

Indoor Jumpstart Sowing

For a jumpstart, sow seeds indoors 6 to 8 weeks before last frost. Keep seedlings in a cool place below 55° F so they can easily acclimate to spring chill. Plant them outdoors in mid-April, about a month before last frost date.

Seasonal Care

Stake tall varieties when sowing seeds or transplanting seedlings - to avoid root damage later. Water deeply and regularly. Mulch to keep roots cool and prolong flowering. Don't over fertilize; a slow-release, balanced 20-20-20 fertilizer at planting time is fine. Compost and other organic amendments help to retain moisture and provide nutrients. Though there are heat-tolerant cultivars such as 'Perfume Delight', most sweet peas poop out in hot summer sun and dry soil.

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