Flowers

How to Grow Moonflower: Planting, Spacing, Care & Bloom

Quick answer

Start indoors 4 to 6 weeks before last spring frost (NC State). Soak seeds overnight in warm water or nick the coat. Low poison severity — seeds (NC State). Not the same as morning glory (I. purpurea). Outdoor transplant frost-week integers are not on the NC species page — plant after frost risk when weather is warm.

Moonflower at a glance

PlantStart indoors: 6–4 wk before last frost
SunFull sun; good drainage; moist soil; wide pH tolerance (NC).
SpacingNC: height about 10–30 ft on supports (also notes ~15 ft); width about 3–6 ft; space about 6–12 feet (wider bands listed).
Days to bloomBlooms summer to fall (NC State)
-7-6-5-4-3-2-1LF+1+2+3
■ Start indoors   ■ Plant out   ■ Harvest
Weeks relative to last frost (LF). Colored weeks show when our ZIP planner schedules each step.
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Updated

Safety: NC State poison severity Low for Ipomoea alba. Symptoms: vomiting; large amounts of seeds may cause hallucinations. Toxic principle: indole alkaloids. Poison part: seeds. Contact dermatitis: no. Keep seeds from children and pets; do not ingest. Not medical advice. (NC State Ipomoea alba)

Moonflower (Ipomoea alba) — night-blooming tender perennial vine grown as an annual. Distinct from morning glory (I. purpurea).

White moonflower bloom
Moonflower (Ipomoea alba). Photo: Jebulon, Wikimedia Commons, CC0 (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

NC State: “Start 4 to 6 weeks before the last spring frost by soaking seeds overnight in warm water or nick with a file to break the seed coat.” Grown as an annual in cooler zones; blooms mid-summer into fall (flowers open late afternoon/night). (NC State Ipomoea alba) Planner: Start indoors last frost −6 to −4. Outdoor set-out frost-week integers are not on the species page — state qualitatively after frost risk / when weather is warm; do not copy morning-glory handbook offsets.

Depth and spacing

NC: height about 10–30 ft on supports (also notes ~15 ft); width about 3–6 ft; space about 6–12 feet (wider bands listed). Needs fence, arbor, or trellis.

Sun, soil and water

Full sun; good drainage; moist soil; wide pH tolerance (NC). Slow early growth until very warm weather, then rapid.

Care

Provide vertical support. Optional: large container and bring indoors to overwinter (NC). Low maintenance.

Bloom

Night-blooming fragrant white flowers mid-summer into fall (NC). Host for hummingbird moth / sphinx moths. No numeric days-to-bloom sourced.

Pests and diseases

NC State: “No significant problems.” Usually none needed.

Related: morning glory · ZIP planner

Frequently asked questions

When do I start moonflower indoors?

4–6 weeks before last spring frost; soak or nick seeds (NC State).

Same as morning glory?

No — Ipomoea alba (night white) vs I. purpurea (day colors). Separate pages; both have Low seed toxicity.

Are the seeds toxic?

Yes — Low severity; seeds (NC State). Do not ingest.

Sources