Moonflowers from seed

Judith Adam

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Moonflower vine (Photo courtesy of Summer Hill Seeds)

Some years ago I found pots of moonflowers (Ipomoea alba, syn. Calonyction aculeatum) started in a nursery. These are a species in the morning glory genus, and you can see the resemblance in their large, pure white trumpet flowers, twining vines and heart-shape foliage. Moonflowers are distinguished by their night-blooming schedule (opening in late afternoon), and an intoxicating fragrance that moves through the garden in the dark hours. The vines grow 10 to 20 feet (3 to 6 m) long, and the flowers can be six inches (15 cm) wide. It became an anticipated event each evening to sit with a glass of wine and watch the flowers swirl open right on cue. Just in case you miss this, they stay open until late morning the following day. I’m trying moonflowers from seed.

Moonflowers love heat, and the ones I found had been growing under glass in a hot greenhouse. They needed only another few weeks of growth before flowers began appearing. However, when I tried to start some myself one year, my garden was too cool and all I got was vines and foliage — no flowers. They grow slowly in cool weather; heat makes them turn on the speed, leap up a trellis and start to bloom. I can’t be sure of finding them in a nursery, so I’m going to try seeds again this spring. Providing constant bottom heat from a heating pad may trick them into growing mode before going outdoors.

The seeds are large, with thick coats that need nicking with a knife or nail clipper before being soaked overnight. Plant them in soilless mix in four-inch (10-cm) pots and provide bottom heat. They’ll germinate in 10 days. Grow them indoors (you may need to provide a small trellis in the pot) under grow lights or in a bright, sunny window for about four weeks. Move them outdoors in late spring when days are warm. Give them lots of sun and consistent moisture, and feed every four weeks with a fertilizer that has a higher middle number (such as 5-10-5) to encourage flower bud development. If you’re fortunate to get blooming plants by midsummer, you’ll also need something nice to drink as you watch the nightly show.

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6 thoughts on “Moonflowers from seed”

  1. Moonflowers bloom at night and give off an alluring scent that makes your garden more attractive. You just need to know when to plant moonflower seeds to enjoy their presence. In short, it’s best to start a moonflower garden between late February and May when the weather is frost-free.

  2. Here in south central Ontario I have these moonflowers that are certainly not vines! They resemble more the Datura in the type of plant they grow into but Datura they aren’t! I’ve seen the range of heights from seed to shy of two feet to nearly four- five ft in a year/season. They open late evening, smell awesome and come fall the flowers become these hard cardboardy shells full of spikes that will dry out and open to spread their seeds.
    My question is are they acidic loving,,, and what do they need to thrive beyond lots of sun? I’ve started from seed, they’re five inches high and it’s end of June. How or what can I do to get some results this year?

  3. Hi Judith, You say moonflowers love heat: is a south facing fence too hot for them in zone 4 garden?

    Thanks for great info!


    • From Judith Adam: Thanks for your question regarding moonflowers and heat. A southern exposure should be perfect for moonflowers. Growing in full sun will require frequent irrigation because moonflowers have large flowers and lots of foliage dependent on consistent moisture. When you figure out the timing of when the flowers spiral open in early evening, I’m sure you’ll be there for the show!

  4. Hi again, Helen (Jan. 21),

    Start the seeds early, perhaps in late April. They take a lot of growing to reach blooming size. Good luck to us both!

    — Judith

  5. Thanks Judith for the helpful hints – nick the seed, bottom heat – for growing the Moonflower Vine from seed. I have failed in my prior attempts so will follow your advice and try again this Spring!


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