Moonflower vines are a quiet delight of the waning season. They are morning glory’s nocturnal cousin, and their wide, near-luminous white blooms begin to unfold every twilight at the end of summer. As the days continue to contract, and nights lengthen, a signal is sent to these photoperiodic tropical vines to begin making buds. At first, the blooms can only be enjoyed if you are out there with them, in the dark, but as temperatures cool and nights grow even longer, the flowers last well into the morning hours, and also open earlier in the day. At their peak they resemble an ethereal collective of sensitive and perfumed radio telescopes, poised to listen to something beyond our reach.
Photography by Marie Viljoen.
Above: The first moonflowers open at dusk. As nights lengthen they open earlier, and last longer.
Ipomea alba is native to the tropical Americas and as far north as Florida, where it is a perennial. In cooler climates moonflower is grown as an annual climber whose tendrils can be expected to exceed fifteen feet.
Above: Night-scented moonflowers attract sphinx and hummingbird moths.
As a small-space gardener, I value moonflower vine for its ability to grow in a (large) pot, cover a trellis or railing in heart-shaped foliage within a couple of months of sowing, and for its exceptionally beautiful flowers, whose structural appeal is mesmerizing—try watching a six-inch long bud as it unspirals slowly and unfolds until full-blown—a botanical meditation. And then there is that fragrance, which sometimes lures long-tongued moths to visit after dark.
Above: Moonflowers begin to bloom in July, reaching peak bloom a couple of months later.
Keep It Alive:
- Moonflower seeds will not germinate if temperatures are too low. Don’t even think about sowing them outdoors until nights remain consistently above 55°F (which means that the soil temperature is warm enough). The same goes for seedlings bought at nurseries. Watch the weather and plant them only once that nightly benchmark of 55° has been reached. In my USDA growing zone 7b that is around mid to late May.
- The seeds should be soaked before sowing to soften their hard, protective capsules. This may take 12 to 24 hours.
- Moonflowers are slow to take off. These vines will not sprint out of the starting gate. Instead, expect them to begin their fastest growth about two months after sowing.
- For container gardeners, choose a large pot to sow them in, at least 16 inches in diameter. Moonflower vines are rambunctious and need room to grow to their full potential. They will also need a deep and daily watering.
Above: Planted near seating, moonflowers’ delicate form offers a floral meditation.
Above: As days cool and nights grow even longer, the flowers open in the afternoon and last well into the morning hours.
Above: By late September many blooms open daily.
Cheat Sheet
- Moonflowers are Ipomea alba, a night-blooming morning glory.
- They are native to the tropical Americas.
- Despite their common name, they will bloom during the day as nights grow longer.
- Do not grow them in Hawai’i where moonflowers are invasive.
- The common name moonflower also refers to Datura species.
Above: Moonflowers can share a vertical growing space with summer crops like beans.
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