Others are heirloom varieties, passed down from gardener to gardener through the decades. Two basic types of sweet peas are available. Both types make wonderful cut flowers that fill the house with their sweet, old-fashioned fragrance. Plant sweet peas early, as soon as the soil can be worked in the spring. Sweet peas grow best when planted during the cool days of late winter or early spring in western Oregon and a little later in the higher elevation areas east of the Cascades, according to Ross Penhallegon, horticulturist with the Oregon State University Extension Service.
Sweet peas prefer well-drained soil in a sunny location.
To ensure success, dig a 1-foot deep trench. Plant the seeds 1 inch deep, spaced 1 inch apart. Thin the seedlings to 5 or 6 inches apart. To guarantee that your sweet peas survive frigid days and nights after planting, try using some protection such as a cloche, cold frame or a cut off gallon milk jug over the young plants. When the seedlings are about four inches tall, pinch off the tip of the stem above the topmost leaves to help create a bushier plant with several flowering branches.