Moonflower Vine Is the Most Magical Night-Blooming Plant You Can Grow
Moonflower (Ipomoea alba), with its large, pure white blooms, pleasant scent, and heart-shape leaves, is one of my favorite vining plants. As the name might suggest, the blooms of this vigorous vine are indeed moonlike, thanks to their pale color and roughly round shape, but actually, they earned their moniker because they open only at night or on cloudy days. Because of this, I like to use them to fill a nocturnal niche in the garden accomplished by few other flowers. And much like their cousins, the more common morning glories that bloom during the day, moonflower vines are very easy to grow in the right location.
Because of moonflower vine's tendency to bloom at night, you might be wondering why you should plant it at all if you can't see the flowers open during the day. The answer is simple: It is magical when you grow it where you spend time outdoors in the evening, perhaps on your front porch or back patio. There, you'll be able to enjoy the huge white flowers that almost seem to glow in dim lighting, as well as the sweet scent these beauties produce. Moonflower vines, which are native to the warmer regions of the Americas, even attract fascinating nighttime pollinators like large, green luna moths and hummingbird-like hawk moths.
It's also worth pointing out that there's another plant that goes by the name moonflower that is sometimes confused with this vine. Jimsonweed (Datura spp.) also has large white flowers that are often fragrant, but this plant does not grow as a vine, nor does it have heart-shape leaves (all parts of it are also very toxic to pets and people so use caution around it).
How to Grow Moonflower Vines
Over the years, I've tried these quick-growing vines in several locations throughout the yard, and they almost always seem to do their best in areas where they can quickly jump up into full sun once the seeds germinate. The warmth and light encourage these plants to produce thickets of thin green vines that wrap around anything they encounter. They can quickly reach well over 15 feet, so it's a good idea to provide a trellis or other support for them to climb.
I've also had some success growing moonflowers in large ceramic pots (from $44, Etsy) to enjoy on my patio. Rather than producing the mass of vines and leaves they do when planted in the ground, being root-bound in a container seems to help them bloom earlier in the season. However, the potted vines don't seem to thrive quite like the in-ground ones.
Moonflowers prefer consistently moist soil and will quickly wilt in full sun without a steady supply of water. However, they will pop right back up if they're watered quickly enough. A regular fertilizer regimen is also important, especially when planted in pots. I usually use a "bloom booster" fertilizer that is high in phosphorus. Avoid a high nitrogen fertilizer because you'll end up with large green plants but fewer flowers.
I would also recommend planting moonflowers along with other vines, such as morning glory or trumpet vine that will have flowers open during the daytime. One of my favorites is red morning glory—it catches the eye during the day and fades in the evening, just when bright white moonflowers appear, creating a mesmerizing color change in the garden as the sun sets.
Though perennial in areas without deep freezes (USDA Zones 9-11) during the winter, moonflowers are usually treated as annuals and are replanted each year. In the warmer climates, this plant can reseed itself, so if you don't want it to multiply, I suggest deadheading the vines. Also be aware that the seeds are toxic if swallowed, so keep them away from pets and young children or make sure to trim away spent flowers before the seeds can develop.
To start moonflowers from seeds, you'll need to nick the thick seed coats with a file first or leave them to soak for a few days before planting to help water get through. If you live in more tropical climates where the vines don't die in winter, you can cut the stems back in the fall and allow them to regrow. This is an easy way to minimize their tendency to climb where they're not wanted and to keep them looking tidy.