Plant Sweet Pea Seeds: Start seeds in winter or early spring, about 6 to 8 weeks before your last frost date. Prior to sowing, nick the outer seed coating with nail clippers to allow for faster hydration and improved germination. Sow in 4 in. pots, using a seed starting mix, with 2 to 3 seeds per pot. Sow seeds ½ to 1 in. deep, keep out of direct sun until germination occurs. With soil temperature kept at 55 to 65°F, germination is in 7 to 21 days. Thin seedlings down to 1 per container about 1 week after germination. Transplant into the garden once soil can be worked and seedlings have 2 to 3 sets of leaves. In mild climates, seeds can be directly sown in fall. Plants grow best with 6 to 12 in. spacing.
Grow Sweet Peas: Full sun to part shade. Rich, moist, well-drained soil. Protect young seedlings from slugs, snails and birds. For fuller plants, pinch or cut back seedlings when there are 3 to 4 sets of leaves. To promote a longer bloom season, deadhead frequently.