EASIEST TO START OUTDOORS
Sweet peas must have well drained soil, so dig deeply and enrich with aged manure or compost before sowing seeds. Erect a well-anchored trellis, vertical netting or other support for vines before planting. Sow seeds in full sun in cool early spring weather as early as the ground can be worked. In mild winter areas, where the ground does not freeze, seeds can be planted in fall, form strong root systems, then overwinter to bloom strongly in spring. Plant seeds 1 inch deep and 2 to 3 inches apart. When seedlings are 2 inches tall, thin them 4 to 5 inches apart, to allow plants room to mature.
Sweet peas bloom best before the weather gets too hot, so if spring planting, sow as soon as ground can worked. Where summer heat comes on fast, they’ll appreciate a spot with afternoon shade. Anchor supports well as vines will grow heavy with bloom. Protect seedlings from birds, slugs and snails. Mulch and keep well watered. For longest bloom, pick flowers often and keep faded blossoms cut.