Charming sweet peas

Flower & Garden Magazine, Feb-March, 1995 by Mary N. Ganter

Like So Many Good Things, Sweet peas do not come easily. Fragrant, elegant and old-fashioned, they are a flower that must be earned by a gardener's work. Perhaps they were once easier and sweeter, in their pre-hybrid youth, but the sweet pea charm lingers undiminished. To see them growing nowadays gives both surprise and pleasure.

Sweet peas are native to Sicily, the mountainous island off the southern Italian mainland. In their native habitat, they prosper in cool, thin woods, along river banks, in mountain foothills and on beaches. They grow as perennial climbers bearing small, strongly scented blue and purple flowers. Cultivated sweet peas, Lathyrus odoratus, are classified as hardy annuals.

Breeders began in 1718 to produce variations of the wild sweet peas, and by 1900 there were more than 250 different varieties grown. These early hybrids are now grouped under the name Grandiflora. Their flowers are small, straight-petaled and intensely fragrant. They are sometimes hard to find, having been replaced in most seed catalogs by newer and showier hybrids. Grandifloras have a reputation for being easy to grow and far sweeter than the Spencers, which supplanted them.

Spencers, however, are probably the most popular type of sweet pea. They are bred for large flowers and ruffled petals over a range of colors from red to blue, pink and white, including all imaginable shades between. Many Spencers - 'White Supreme,' for example - legitimately claim a characteristic scent, and these are a good compromise for gardeners who would rather not choose between flower and fragrance. Several of the new American-bred strains like 'Early Mammoth' rival the Spencers on both counts and are earlier blooming and more forgiving about soil conditions.

Cuthbertson sweet peas, developed in the 1940s to tolerate warm conditions, are also popular and widely available. Cuthbertsons bear large, practically scentless flowers in white, red, purple and a wide range of pink shades. Their long stems make them ideal for a cutting garden.

All sweet peas, antique or modern, retain a strong genetic nostalgia for the Sicilian climate. They insist upon cool temperatures and prefer rich soil, but each type can be persuaded to grow in most parts of the United States if planting is timed properly.

In the southern tier of states, and anywhere else the ground doesn't freeze, sweet peas should be planted in late fall (November to January) for spring bloom. In exceptionally mild winter areas, like parts of Florida, Texas and California, it is possible to sow seeds in late summer (August to October) for flowers after Christmas. In these very temperate places, Cuthbertsons usually bloom longest but other types may succeed given optimum conditions.

In New England, the Pacific Northwest and other hard winter climates where Spencers and Grandifloras perform best, sweet peas should be planted as soon as the ground is workable in the spring (March to May). The soil will certainly be cold; snow may fall once or twice more, but the seed must be in the ground, waiting for spring.

This is a breath-holding business. Seeds are slow to germinate in chilly soil, but since sweet peas seldom thrive as transplants, gardeners must take the risk or do without. To speed germination, gardeners planting sweet peas in spring can soak their seed. Even so, all aspiring sweet pea growers should plant plenty of seed.

The best results for both spring-and fall-planted seeds are achieved by thorough preparation of their bed in autumn. In some cases, it is possible to do both bed work and planting in the very early spring, but in the coldest climates this is almost always hopeless.

To make a bed for sweet peas, dig a trench two feet deep and at least one foot wide. Four to six inches of aged manure or compost should be put in the bottom and the trench refilled with rich earth. If fall planting is indicated, seeds should be buried two inches deep, one inch apart and the entire bed heavily mulched. If planting is delayed until springtime, the top of the bed should be mounded so that the soil that receives the seed will be looser, warmer and drier than the ground beneath.

Sweet peas can be grown in containers if they are fed and watered attentively and have the benefit of fresh, cool air. They are not, however, a flower for hot city balconies or traffic-exposed porches. Climbing varieties may be raised in large containers, but dwarf (12 inches and under) and intermediate (15 inches to 3-1/2 feet) types are designed for the purpose. The variety `Snoopea' has no tendrils and needs no support, but 'Bijou,' the most available dwarf, requires support to look its best. Container varieties seldom have a compelling fragrance.

Whether sown in pots or trenches, the vines must be thinned to stand 6 inches apart, and supported. Both duties should be performed when the plants are about 6 inches tall. At first, slim twigs or bamboo should be used to train the stems, but as the plant produces tendrils, more substantial support will be needed. Vining sweet peas take no interest in life if they are left to sprawl upon the ground. Twiggy brush is a traditional support material, but systems involving string or plastic netting may also be useful. Chicken wire and similar products work too, but can cook plants in warm weather.