Gardeners have been enjoying sweet peas for centuries, reports Texas A&M University, prizing the plants for their profusion of colorful, fragrant blossoms. The plants may either be the bush variety or the vining type that can quickly cover a trellis or fence. Although you can often buy started sweet pea plants in spring at a garden store, collecting the seeds from an existing plant can comprise an economical method of continuing your sweet pea collection, year after year.
Wait for the sweet pea blossoms to fade and drop off, and for the resulting seed pods to take on a brown appearance, advises the National Gardening Association. Sweet pea plants started in the spring typically achieve full bloom by midsummer.
Pluck off the seed pods with your hands, or sever them from the vine with a pair of gardening shears.
Break open the seed pods over a sheet of newspaper or paper towels. Remove the seeds inside and place them on the paper towels or newspaper. Discard the seed pod pieces and let the seeds dry for a couple weeks indoors.
Pour the sweet pea seeds into an envelope and insert the envelope into an airtight, sealable container. Put the container in a dark and cool area until you're ready to plant the sweet peas. The National Gardening Association recommends putting them into your refrigerator.