Sunday, April 6

Heaven scent

Sweet peas are a garden treasure

An heirloom variety, 'Cupani's Original' is also one of the most heat-resistant and fragrant sweet peas.

Sweet peas (Lathyrus odoratus) have been a garden favorite for centuries in both American gardens and their European ancestors. As the 20th century unfolded, plant breeders were working hard to create bigger, more impressive blossoms and even headier fragrance. Today's versions include bonnet shapes, ruffled petals and colors in shades of pink and maroon, red, salmon, peach and white, as well as bicolor. And their deep, honey-like perfume is intoxicating!

Several years ago a British breeder started reintroducing long forgotten heirloom varieties that are even more aromatic. Among the favorites are 'Cupani's Original,' a rich purple and blue variety named for the Franciscan monk who discovered it at the end of the 17th century. Other varieties include cream colored 'Mrs. Collier,' pink-tinged white 'Fairy Queen' and 'Matucana,' whose richly scented, small purple and lavender flowers are very close to the original Sicilian wildflower from which the sweet pea descends.

Sweet peas in the garden
Sweet peas come in two varieties -- climbers and bush types. The climbers have specialized leaves called tendrils that contact a vertical support and wrap around it in a phenomenon called thigmotrophism, the twining of a plant in response to touch. Climbers top out at five to six feet in most areas, but can reach 12 feet in mild coastal climates. They are perfect for screens and as backgrounds in the garden. Plant 18- to 36-inch annuals down in front to shade and cool the roots and hide the leggy stems sweet peas get with age.

Freestanding bush sweet peas don't need support. They only get about 12 to 18 inches tall and make terrific border and container plants.

Lathyrus likes cooler weather and may wither in the high heat of summertime. To keep the color going you can try heat-resistant cultivars like the heirlooms 'Cupani's Original' and 'Old Spice.' Another alternative is to interplant morning glory (Ipomoea spp.) to eventually replace the fading sweet peas.

Photos/National Garden Bureau 'Streamers Mix' sweet peas come in a variety of striped color combinations including chocolate/white, blue/white, orange/white and red/white.

Growing from seed
Sweet peas are early spring plants. But because the weather can be unpredictable during this time, some folks prefer to start the plant indoors. Six weeks from the last frost date (May 15 locally, so NOW would be a great time!), soak the seeds in warm water over night. Sow two or three in a three-inch peat or other biodegradable pot that can be planted right in the soil -- sweet peas hate transplanting. Store the pots on top of the refrigerator, or use a heating mat to warm the soil. After they've germinated and show their first true leaves, cut, rather than pull the weaker seedlings.

If you'd rather direct sow your sweet peas, sow them in the spring but prepare the bed in the fall, when the soil is dry and warm and you won't risk damaging its structure by working it wet.

Dig a trench one foot deep and fill it with six to eight inches of compost. Cover this with a three-inch layer of topsoil. Place the seeds one inch apart along the length of this slight depression, then top with another inch of soil. Thin the seedlings to five or six inches apart when they have sprouted. As the seedlings gain height, mound soil around the stems.

Care and culture
Sweet peas need a sunny, well-drained site with a slightly alkaline soil. If needed, sprinkle a handful of ground limestone into the topsoil and thoroughly mix in. The plants will need about an inch of water a week, and regular deadheading will keep them blooming. Remove the spent flowers and the entire stem back to the main vine.

These gorgeous flowers are heavy feeders, so every two weeks alternate feeding them with a balanced 10-10-10 liquid fertilizer and a fish emulsion.

Lathyrus odoratus 'Black Diamond.'

Lathyrus isn't plagued by too many diseases, but keep an eye out for powdery mildew. If you see the white fuzz on the leaves, spray with a mixture of one gallon of water and a tablespoon of baking soda. Crinkled leaves and flower petals indicate aphids, which should be sprayed every two weeks with an insecticidal soap. Birds and slugs also like to get at young plants, so keep netting over the seedlings until they're about 18 inches tall and sprinkle non-toxic Sluggo(r) according to package directions to control slugs and snails.

For a reliable, old-fashioned method for warming the soil in order to start sweet peas outside, plus a list of terrific modern and heirloom sweet pea varieties, click here.

Active in the horticultural industry since 1994, Glen O. Seibert is a former editor for Garden Gate magazine and now works as a writer, landscape designer and self-professed "gardening media mogul."