Ornamental · Convolvulaceae
Moonflower
Ipomoea alba
Plant it in full sun and warm soil, and the moonflower unrolls fragrant white trumpets every evening.
Full sun
Every 3–7 days
50–90°F · 10–32°C
60–120 days
Overview
Moonflower is a fast, twining vine grown for one nightly show. As dusk falls, fat buds unwind into pure-white, fragrant trumpets as wide as a saucer, drawing in the sphinx and hawk moths that pollinate them, then close again by the next morning. It belongs to the morning glory family and behaves like its day-blooming cousins, just on the opposite schedule.
Given heat and a sturdy support, it climbs hard and fast, reaching well over head height in a single season. It is a tender perennial in frost-free ground but most gardeners grow it as an annual, sowing fresh seed each spring. The scented evening flowers make it a favorite for porches, arbors, and any spot enjoyed after dark.
It asks for little once it gets going. The two things it will not forgive are a cold, short season and overly rich soil, both of which leave you with a wall of leaves and almost no flowers. Get the warmth and the lean soil right, and the rest is mostly giving it something to climb.
Care
The short version: full sun, warm and average (not rich) well-drained soil, and steady moisture, with a strong trellis or fence for the vine to climb.
Light
Give moonflower full sun, ideally 6 or more hours a day. It will tolerate a little afternoon shade, but anything less than full sun slows the vine down and cuts the number of flowers you get.
Water
Keep the soil evenly moist without letting it stay soggy, watering roughly every 3 to 7 days depending on heat and rain. Steady, medium moisture suits it best, and well-drained ground keeps the roots happy.
Soil
Average, well-drained soil is exactly right, whether that is loam, clay, or sand. A pH anywhere from 6.0 to 7.8 works fine. Skip the rich, heavily amended beds, because lush soil pushes leaves and holds back the flowers.
Temperature
This is a heat lover, comfortable from 50°F to 90°F (10°C to 32°C). It grows fastest in the warmth of high summer and cannot take frost, which ends the plant outright.
Humidity
Ordinary outdoor humidity is plenty, so there is no figure to aim for. The vine takes typical garden air in stride and asks for nothing special here.
Feeding
A light, balanced fertilizer about once a month through the growing season is all it needs. Go easy on nitrogen in particular, since a heavy hand grows foliage and delays the blooms you are after.
Pruning
Pinch out the young tips early to push the vine to branch and fill out. Beyond that, trim away any dead or stray growth and keep guiding the stems onto their support as they climb.
Repotting
In a container, plan to repot once a year. Watch for roots circling the pot, creeping out the drainage holes, or growth that stalls, all signs the plant has outgrown its home.
Size & spacing
This is a big vine, climbing 10 to 30 feet (3 to 9 m) in a good season and spreading 3 to 6 feet (91 to 183 cm) across. Give it a tall, sturdy trellis, fence, or arbor and the room to run.
When to plant
Moonflower needs a long stretch of warmth and dies at the first frost. Nick and soak the hard seeds, start them indoors 6 to 8 weeks before your last frost, and set the plants out once the cold has passed. From there it blooms from mid-summer into fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6-8 weeks before last spring frost, after nicking and soaking the hard seed coat
- Plant: 1-2 weeks after last spring frost once soil is warm
- Harvest: Mid-summer into fall; flowers open at dusk and close by morning
Hardiness
USDA hardiness zones: 10–12
Temperature: down to -1°C
Troubleshooting
Moonflower has few real troubles, and most of them trace back to the weather or the soil. The usual complaint is leaves without flowers; the rest is the occasional pest. Match what you see below and act early.
Plenty of leaves but few or no flowers
A moonflower that grows lush and green yet refuses to bud is almost always running out of warm season or sitting in soil that is too rich. Too much nitrogen pushes leaves at the expense of buds, and shade slows the whole plant down. Move it into full sun, ease off rich feeding, and start seed early so the vine has time to reach bloom before fall.
Fix:
- Site in full sun with a sturdy support
- Avoid rich soil and high-nitrogen fertilizer
- Start seed indoors early in short-season areas to extend the warm growing window
Twisted shoots, speckled leaves, or fine webbing
These are the calling cards of aphids and spider mites, with the odd caterpillar or leaf miner thrown in. Check the leaf undersides and tender new tips, where aphids cluster and mites leave a faint web over stippled, fading leaves. A hard jet of water knocks most of them loose, insecticidal soap handles the soft-bodied ones, and you can pick off caterpillars by hand. None of these usually amounts to much on a healthy vine.
Fix:
- Dislodge aphids and mites with a strong spray of water
- Treat soft-bodied pests with insecticidal soap
- Handpick caterpillars and remove mined leaves
Toxicity
Treat the seeds with respect. Like all morning glories, moonflower carries LSA alkaloids in its seeds, which can sicken pets, livestock, and people and bring on a hallucinogenic reaction if eaten. The leaves are a much milder concern, but keep the seeds and pods well away from animals and children.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
The seeds are the real hazard, since they carry the LSA alkaloids. A cat that eats them tends to drool and vomit, and a larger dose can bring on tremors, a wobbly walk, and disorientation. The leaves are a much milder worry.
Dogs Mild
Dogs that swallow the seeds usually get an upset stomach and vomiting. Eat enough and the same alkaloids can cause agitation, tremors, and a spaced-out, hallucinogenic reaction. Foliage on its own rarely causes more than mild stomach upset.
Horses Caution
Horses are unlikely to seek out the vine, but the seeds hold the same alkaloids that trouble other animals. Keep them away from seed pods, and watch for colic or dullness if any are eaten.
Rabbits Caution
Don't offer moonflower as forage. The seeds in particular can upset a rabbit's gut, so keep the plant and its pods out of the hutch and run.
Livestock Caution
Cattle, goats, and sheep generally leave the bitter vine alone, yet the seeds are still the concern. Fence stock away from any plants setting pods to be safe.
Birds Caution
The seeds are the part to guard against here too. Keep pet birds away from dropped seeds, which can cause vomiting and a jittery, disoriented spell.
People Caution
No part of this vine is food, and the seeds are the danger. Eating them causes nausea, vomiting, and hallucinogenic effects from the LSA alkaloids, so keep seeds and pods well out of reach of children.
Keep seeds out of reach of pets and children; ingestion of large amounts of seeds can cause neurologic signs.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
There is really only one moonflower, the species itself, but it is often grown next to a day-blooming relative. These are the two worth knowing.
Ipomoea alba (species moonflower / moonvine)
This is the true moonflower, a vine that unfurls fragrant, pure-white trumpets up to 4 to 6 inches across at dusk for the sphinx and hawk moths to pollinate.
Day-blooming morning glory (Ipomoea purpurea / Ipomoea tricolor)
A close cousin often grown alongside moonflower so something is always in bloom, since its colorful flowers open through the day rather than at night.
Companions
Moonflower pairs naturally with its day-blooming morning glory cousins, which fill the trellis with color while the moonflower sleeps and then hand the night shift back over at dusk.
Plant near
Day-blooming morning glory (Ipomoea purpurea/tricolor): Planted together they provide round-the-clock flowers, day and night.
How to propagate
Moonflower is grown from seed, and the only trick is getting that tough seed coat to let water in.
SeedEasy
Start indoors 6-8 weeks before last frost or sow outdoors after frost when soil is warm · 1-3 weeks to germinate; rapid growth once weather warms
Moonflower grows readily from seed, but the hard seed coat needs help first. Nick it with a knife or rub it on sandpaper, then soak the seed overnight before planting. Start it indoors 6 to 8 weeks before your last frost, or sow it straight outside once the soil has warmed, and it sprouts in 1 to 3 weeks before taking off fast in the heat.
Myths
The vining moonflower is the same deadly plant as the jimsonweed or thorn apple that shares its name.
These are two unrelated plants that happen to be called moonflower. The vine here is Ipomoea alba, a twining morning glory whose seeds hold mildly toxic LSA alkaloids. The dangerous one is Datura, an upright nightshade whose tropane alkaloids, atropine, scopolamine, and hyoscyamine, can be fatal. Datura is by far the more poisonous of the two, so the name alone tells you nothing about the risk.