Moonflowers can add their incredible beauty and powerful fragrance to a night garden. Moonflower plants have large, beautiful, heart-shaped leaves growing on huge, robust vines that need a large trellis to support them. The iridescent white, trumpet-shaped flowers are around 6 inches long and 3 to 6 inches wide. These spectacular flowers unfurl from cone-shaped buds as the sun goes down and on some cloudy days. Moonflower plants are perfect to grow in an outdoor eating area or near a bedroom window, where their fragrance can sweeten the night air.
- Botanical Name: Ipomoea alba (formerly Calonyction aculeatum)
- Common Name: Moonflower, tropical white morning-glory, moon vine, evening glory
- Plant Type: Perennial flowering vine (grown as annual in temperate climates)
- Mature Size: 8 to10 feet
- Sun Exposure: Full sun
- Soil Type: Sandy, clay, loam
- Soil pH: 6.0 to 8.0
- Bloom Time: Summer to fall
- Flower Color: White, purple
- Hardiness Zones: 10, 11, 12
- Native Area: Tropical and subtropical South America, Central America, Florida
How to Grow Moonflower
Try growing moonflowers with related species of morning glories that bloom during the day for a spectacular flowering display. Day-blooming morning glories will flower when the sun is out, and the moonflowers will take over as the sun goes down.
Moonflower is a self-seeder, so if you don't want it to return next year, pick off the spent flowers so that they don't form seed pods. The plant is usually grown as an annual, but it is a perennial in the tropics.
Grow in full sun for the best blooms. They are adaptable to part shade.
The moonflower is tolerant of a wide variety of soil types and acidity levels, but it does best soil is nutrient-rich loam. It does perfectly well in poor, dry soil, and prefers well-drained soil.
Young plants should be watered regularly until they are established. Moonflower has average water needs and you may water it about 1 inch per week, especially during hot periods. It likes moist soil that isn't soggy. It will tolerate short dry periods but will be killed by a long dry spell without water.
Temperature and Humidity
Growing moonflowers isn't hard in a warm climate since they are tropical white morning glories that can take the heat and high humidity. The U.S.D.A. says that in the United States and its territories and protectorates, moonflowers are native to Florida, Louisiana, Texas, Puerto Rico, and the Virgin Islands, and have been thriving in Hawaii, where they are an introduced species. This vine can become an invasive plant in certain areas of the country, including Arkansas and Arizona, where most species of Ipomoea are prohibited "noxious weeds." But in cooler climates, they are grown as annuals and planted outside when the temperature is consistently 60 to 70 degrees Fahrenheit.
Fertilize regularly with half-strength high-phosphorus fertilizer during blooming season. Avoid high-nitrogen fertilizer as it can promote foliage but not blooms.
Varieties of Moonflower
In general, moonflower seeds are sold without a variety designation, often as an heirloom plant.
Growing From Seeds
If you live in a colder climate, start seeds early.
- Plant indoors, under lights, approximately four weeks before nighttime temperatures are reliably greater than 50 degrees Fahrenheit. The plants take a while to set flowers so make sure to start them early enough.
- Soak seeds in warm water for four to eight hours before you plant them. This will help with the germination rate.
- Start seeds in plantable pots (peat or cow pots work well) because the roots don't like to be disturbed. You can plant your seedling, pot and all; these pots will minimize root disturbance. That said, it is possible to buy moonflower seedlings in plastic pots and transplant them successfully that way as well.
- Once nighttime temperatures have reached 50 degrees, plant seedlings in a large pot.
If you live in a warmer climate, you can sow your seeds directly into a pot, though these are the areas where the plants can become invasive.
- Use potting soil that is fast-draining but doesn't have too much fertilizer. If there is too much fertilizer, you will get lots of leaves, but not many flowers.
- Place your container in full sun during germination.
- Keep the soil moist.
Toxicity of Moonflower
There is general confusion over toxicity because moonflower can refer to different species. Ipomoea alba has been studied in mice and can have some toxic effects, but is considered to be low in toxicity. It is probably still wise to avoid ingesting it and exercise caution for children and pets who might do so. It is listed by California Poison Control as only having effects on the skin, such as a rash.
Meanwhile, Datura inoxia, which is also called moonflower, is very toxic. The Datura plant is related to Jimson weed and all parts of the plant contain high amounts of toxic atropine, scopolamine, and hyoscyamine. The symptoms can include delirium, bizarre behavior, fast heart rate, high body temperature, dilated pupils, and amnesia. It is necessary to protect anyone from ingesting any part of the Datura plant, including seeds and flowers.