Growing moonflowers (Ipomoea alba or Calonyction aculeatum) isn't hard in a warm climate since they are tropical white morning glories that can take the heat. 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.
Yes, they like it hot, but you could also have success growing them in cool climates, although it may not be easy. No matter where they grow, moonflowers are definitely worth the trouble for their incredible beauty and the powerful fragrance that the blooms emit in a night garden.
Robust Vines, Spectacular Flowers
Moonflower plants have large, beautiful, heart-shaped leaves growing on huge, robust vines reaching 8–10 feet or higher that need a large trellis to support them. The iridescent white, trumpet-shaped flowers are around 6 inches long and 3–6 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.
There Are Drawbacks
Before growing the stunning moonflower vines, there are a few things you should know.
The plant is poisonous, particularly the seeds, and 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."
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.
You Can Learn to Grow Them Successfully
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.
Keys points for growing moonflowers successfully:
- 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°F. The plants take awhile to set flowers so make sure to start them early enough. Read some tips on starting seeds as background for this process.
- 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°F, 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).
- You'll want 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. (Follow the directions on the package.)
- Place your container in full sun during germination.
- Keep the soil moist.