TO START OUTDOORS: In late spring once weather is warm and settled and nights stay above 50°F (10°C), sow in a sunny spot in ordinary garden soil 6 inches apart and 1 inch deep. Firm soil over seeds.
TO START EARLY INDOORS: Sow indoors 2 to 3 weeks before last expected frost in individual pots of seed starting mix. Cover 1 inch deep and keep warm and moist. Provide a strong light source until seedlings are ready for outdoor planting. Transplant very carefully once nights stay above 50°F (10°C) and before seedlings get too crowded. Thin or transplant seedlings 10 to 12 inches apart. Be careful not to disturb roots.
GROWING NOTES: To speed germination, nick the edge of each seed with a nail clipper, or soak for no longer than 8 hours in tepid water. Plant immediately after soaking. Erect well-anchored supports at least 8 feet tall at planting time; strong netting, a wood or wire fence or a sturdy trellis serve well to hold these vigorous climbers. Moonflowers need a long warm growing season. Combine with dawn blooming morning glories for a spectacular late summer display both night and day.