The sweet pea, Lathyrus odoratus, has been in cultivation in Europe and the United States for three hundred years. It was easy to hybridize—think of Gregor Mendel and the elegantly simple experiments he carried out on peas to demonstrate how genetics worked—and the flowers themselves were popular as cut flowers in the Victorian era, when short-stemmed, ephemeral, highly scented flowers were popular. At the end of the nineteenth century, the most popular form was the Grandiflora, which was known for its large, sturdy blossoms, new colors, and wild, old-fashioned fragrance. A few years later, the Spencer types, with ruffled petals and even larger flower head, came into vogue and have never quite gone out of style again. Spencers and Grandifloras have also been cross-bred to expand the range of colors for both.
When you’re choosing a sweet pea to grow, there are two things to consider: growth habit and temperature. A sweet pea will either be classified as a dwarf or a climber; for the most part, you’ll select dwarf-style plants for containers and climbers to scramble up a fence or a trellis.
Subtle changes in temperature and day length also make a difference, so if you’re going to try to keep sweet peas going year-round, it’s a good idea to switch to a winter-blooming variety when temperatures drop and go back to a heat-tolerant summer variety when it warms up again. Renee’s Garden Seeds, for instance, offers ‘Velvet Elegance,’ which blooms early in cool weather, and a more heat-tolerant ‘Perfume Delight’ for summer. As a rule, red and orange varieties can’t take the heat, so although it may wreak havoc with your seasonal color scheme, you’re better off planting pastel varieties to bloom in the hottest months of the year.
The most economical way to start sweet peas is to grow them from seed. The seed is covered with a tough coating; most companies now sell them pre-nicked to encourage better germination. If yours don’t already have a fine slit in the coating, you perform the operation yourself with a knife or simply move on to the next step, which is to soak the seeds. (I know this sounds like a lot of work, but come on, these are sweet peas we’re talking about here.) Wrap the seeds in damp paper towels and set them in a warm spot—a window sill, maybe—and within several hours, they will have started to swell, which means that germination has begun. Now you can plant them. And if that’s too much trouble, look for sweet pea plants from Annie’s Annuals or at nurseries around town. They’re foolproof and fabulous.
Now—where to plant them? A chicken wire or chain link fence works well, as does any other trellis or wall that has been covered in the kind of fine mesh netting or string they need to get a grip. Bird netting is nearly invisible against a wall and is easy for tendrils to grab. You can also start seeds in a pot and transplant them later, when the plants have plenty of young tendrils and look ready to climb.
Pick a site with full sunlight and dig in plenty of aged compost—sweet peas like rich, loose soil. Work in a little bone meal before you plant. Keep the soil damp (soaker hoses are great for sweet peas because they’ll keep the roots moist without getting the vines wet) and feed with a weak solution of fish emulsion every couple of weeks. Finally, don’t be shy about cutting the flowers—it’s absolutely essential that you keep seed pods from forming, because once the plant starts making seeds, the show’s over. I start out very carefully cutting individual stems and placing them in slender, narrow vases or even champagne flutes, but by the time the vine’s mature, I’m chopping off whole sections of vines and dropping them in water. Anything to keep the plant from getting ahead of me. (And by the way, the cut flowers will last nearly a week in the vase if you use commercial flower food, change the water, and keep them out of the sun)
To keep a crop of sweet peas going throughout the year, start a new batch every month or two. Ideally, each new batch would get its own freshly-dug space to grow in, but I don’t have enough space for that in my garden, so I continue to plant new seedlings in the same row around my chicken coop. They scramble up the chicken wire and provide a little shade for the birds. By cutting back the old vines drastically as they start to go to seed, I create enough room for the young seedlings to climb.
If you’re really into sweet peas, whatever you do, don’t go buy Graham Rice’s The Sweet Pea Book. It’s sheer torture. I flipped right to the photograph of the tangerine and cherry-colored ‘Glow’ on page 61 and just about passed out on the spot. As far as I can tell, it’s only available from one seed company in England, and I can’t get an e-mail through to them. (Does anyone get the Unwins seed catalog, or am I just going to have to go over there myself?) Then there’s the heavenly “Lavender Bridesmaid,” a dwarf bicolor that is described as “white with pretty purple whiskers and purple wire; shaded purple at the top; bolt of deep purple on reverse.” What this means in non-sweet pea speak is that it’s the most gorgeous, delicate lavender and white flower you’ve ever seen. I may have to go to England for that one, too.
But there’s no reason to travel that far; you’ll find a great selection at local nurseries and garden shops, and if you need a few hundred more choices, check out Fragrant Garden Nursery in Brookings or Enchanting Sweet Peas in Sebastopol.