Moonflower, as a member of the Ipomoea genus along with morning glory, is recognized as having hallucinogenic seeds and being mildly toxic to humans and pets. Gardeners should be cautious about their use of any Ipomoea species in homes with small children or where dogs, cats, or horses are present. If you don’t want the vines to reseed in your garden, remove the spent flowers before they can drop seeds. This deadheading process also can promote further blooming on the vines. When growing moonflower as an annual, most gardeners prefer to start new plants the following year rather than trying to overwinter their plants; the vines can be difficult to maintain indoors. When grown year-round outdoors as a perennial, the vines can be pruned back and shaped as needed in the fall. Thin the stems to improve airflow around the plant and open it up to sunlight. In very warm regions of southeast and south-central U.S. and in Hawaii, this plant is considered invasive and should be grown with caution against its escape into natural areas. Such caution is not needed in cooler regions where the plant dies out yearly.
Light
Moonflower grows best in full sun, meaning at least six hours of direct sunlight on most days. It can adapt to partially shady conditions, though it might not flower as well.
Soil
This vine can tolerate a variety of soil types. But it prefers a rich, loamy soil with good drainage and a slightly acidic to neutral soil pH.
Water
Moonflower likes a moderate amount of soil moisture. Water young plants regularly, so their soil stays moist but not soggy. Soil that’s too wet can cause the roots to rot. Water established plants when the top inch of soil feels dry. The vine will tolerate short periods of drought, but a long dry spell can kill it.
Temperature and Humidity
These vines thrive in the summer warmth and humidity in zones 3 to 9, and will be perennial in zone 10 to 12. If you live in a cooler climate, wait to plant them outside until the temperature is reliably around 60 to 70 degrees Fahrenheit. Native to tropical climates, these plants prefer a fairly high humidity level but will tolerate dry air if they are kept well-watered.
Fertilizer
Fertilize every three to four weeks with a half-strength, high-phosphorus fertilizer when the plant is in bloom. Avoid high-nitrogen fertilizer, as it can promote excessive foliage growth at the expense of blooms.
Types of Moonflower
In general, Ipomoea alba is sold without a variety designation. Some similar plants that also use the common name moonflower include:
Ipomoea leptophylla: This is an erect, flowering plant that sometimes goes by the name bush moonflower or bush morning glory.Ipomoea violacea: This plant is commonly known as the beach moonflower or sea moonflower, and its white flowers also open at night.
Propagating Moonflower
Moonflowers are fairly difficult to propagate by rooting vegetative stem cuttings, so it’s rarely attempted. However, the plant self-seeds very freely, so it’s quite easy to obtain new plants by transplanting the volunteers that readily sprout up from seeds dropped in the garden. Here’s how:
How to Grow Moonflower From Seed
If you are harvesting seeds from an existing vine, make sure they have fully dried before you collect them from the seed pods left behind after the flowers fade. Start seeds indoors roughly four to six weeks before your area’s projected last frost date. Soak the seeds overnight in warm water or slightly nick them with a file to break their hard coating. Then, plant them about 1/4 inch deep in a seed-starting mix. It’s ideal to use small biodegradable peat pots that you can just bury in the garden, as moonflower doesn’t like its roots disturbed with transplanting. Place the seeds in a warm spot that gets bright, indirect light, and keep the soil lightly moist until seedlings appear. Once outdoor temperatures are reliably warm, you can begin acclimating the seedlings to direct sunlight by placing them outdoors for increasingly long stretches each day. After about a week of this hardening-off procedure, the seedlings are ready to be planted outdoors.
Overwintering
In cold-winter zones where you are growing moonflower as an annual, pull the entire plant from the ground when the flowers have faded and the foliage begins to wither and turn brown. Leaving the vines in place may lead to a vast number of volunteer seedlings in the spring. Because these plants self-seed so vigorously, it’s best not to add the dead plants to compost heaps, since many seeds are likely to survive. In warm-weather zones where moonflowers continue to grow as perennials, winter is a good time to survey the ground and pluck out volunteer plants to prevent uncontrolled spread.
Common Plant Diseases
Moonflower can fall prey to black rot, a bacterial disease that thrives in humid conditions. It can be remedied by separating thick vines to promote air circulation, and never watering from overhead or at night, which will keep the plant drier.
How to Get Moonflower to Bloom
When beautiful and mysterious moonflower’s creamy, white blooms open at night they provide a light, sweet fragrance. The plant produces flowers all summer till the frost: deadhead blooms you can reach, but it will continue to flower if you can’t get them all. Moonflower generally blooms reliably if it’s getting enough sun and if it’s watered regularly. And adding fertilizer to your watering routine—moonflower likes a high phosphorous variety—will help your plant produce more flowers.
Common Problems With Moonflower
Moonflower is an easy-going plant that needs very little care. But it can have a few problems that are easy for any gardener to fix.
Yellow Lesions on the Edges of Leaves
This more than likely means your moonflower has black rot, a bacterial disease that if left untreated will force your plant to drop its leaves. But you can fix this because it comes from over-crowding and too much moisture: Untangle your vines to space them out, and never water in the evening or from above.
Seedlings Die for No Reason
This is called damping-off disease, and it happens to seemingly healthy seedlings without warning. To keep this from happening, do not over-water seedlings, and do not overcrowd them in your garden. Thin your plants out so they get more air circulation; this should help avoid damping off. When starting seeds, using a porous seed-starter mix rather than standard potting soil, and making sure air circulation is good can prevent damping-off fungus.
