If you want to add beautiful drama to your landscape this summer, buy a small pack of moonflower seeds (Ipomea alba) and prepare to be amazed. From a pea-sized seed, you will grow an 8 to 20-foot vine covered in 6-inch white flowers in two months. It’s an annual plant in our temperate region, so once it freezes it will die—but not before producing plenty of seed for next year.
The name originates from the whirled flower buds that open over a fairly short time in early evening, and then bloom all night. By the time it gets warm the next morning, the flowers are spent as each flower blooms only once. Fortunately, new flower buds replace them each day, and continue this nocturnal ritual. Their beauty and fragrance are intoxicating to both people and the largest moth you may ever see—the sphinx or hawk moth. This moth is the size of a hummingbird, and behaves a bit like one too. It is a thrill as they buzz around you, gathering the moonflower nectar.
Choose a site in full to part sun, where this diva can climb and spread out. And I don’t mean a mailbox or tomato stake. One plant can cover a 10-foot fence, and two or three plants will create a formidable fortress of green and white. They don’t need particularly rich soil, and don’t overdo it on the nitrogen or you will have all green and no flowers. Some compost and adequate water will keep this luscious vine hydrated and vigorous through the summer and fall. Deer do like moonflowers, but this vigorous vine can withstand some grazing while it grows beyond their reach.
The seeds are very hard, so you will get a better germination rate if you “scarify” them. This entails roughing up the hard exterior seed coat so moisture can penetrate. In nature this happens due to rocks in the soil or freezing and thawing, but you can accomplish the same goal by scratching the seeds with sandpaper, or a nail file or carefully cut the hard seed coat with a knife. Then soak the seeds in water overnight and see which ones swell up. If they stay hard and small, you may need to scarify them again.
Plant the swollen seeds directly in the soil once outdoor temperatures are very warm. You can plant them in pots indoors to try and speed up the season, but I have found that if you just wait until mid-May or June to plant the seeds in the ground, they will quickly catch up and even surpass the potted ones. Moonflowers start out slow, but don’t be fooled into trying to speed them up with fertilizer. Once they get a good root system their growth will astound you.
Moonflowers look gorgeous all alone, or you can mix them with other vigorous climbers like the sweet autumn clematis (Clematis terniflora) with tiny white flowers or hyacinth bean (Lablab purpureus) with purple flowers and pods. Although moonflowers are in the morning glory family, they are not weedy like their daytime blooming cousins, which I can’t recommend planting in combination (or in the south at all, for that matter!).
The attractive seed pods dry on the vine and you can collect them in late fall to save for next year. They may self-seed the following year, but if so, in very small numbers and they are easily removed if not desired.
For a very small investment, you can put on a live show in your garden this year. Invite your friends over for fresh basil pasta, a glass of wine, and an evening of watching the moonflower and moths do their dance in the dusky evening hours.
Featured image – Moonflowers by Jeana Myers
Jeana Myers, PhD, is the Horticulture Agent for Wake County. For gardening questions, contact the Extension Master Gardeners of Wake County at 919-250-1084 or email firstname.lastname@example.org.