How to get moonflower vine to thrive and bloom in Seattle?
January 25, 2011 9:08 PM   Subscribe

Help me finally get a moonflower (Ipomoea alba) to thrive and bloom in my Seattle garden this year.

I have planted moonflowers (aka Moon Vine, Ipomoea alba) in my Seattle garden every year for 7 years. I've started them from seed in my greenhouse and transplanted them, I've transplanted seedlings purchased from local nurseries and mail-order nurseries, and I've planted the seeds directly in the ground once it's warmed up.

Most years they don't grow very tall (less than two feet). (Neither do my other Ipomoea vines, but at least I get blooms on those.) I have never had a single bud, much less a blossom.

Is it heat they need? More sunlight? More humidity? More frequent watering? I could grow them on in the greenhouse, but I don't really have a green thumb for houseplants, which is essentially what they would be--plants do better under my care when they are, well, somewhat protected from my efforts by being directly in the ground, outdoors.

Is it hopeless to try to get these annuals to bloom in the Pacific Northwest? I'm willing to use any soil amendments and/or fertilizers to get a bloom.

Bonus question: What other plants work well in evening gardens here? I've had success with night phlox and evening stock (for nighttime fragrance), and for white blooms that stay open at night, four o'clocks, petunias, cosmos, and cleome have done well in my garden. I've been intermittently successful with datura (angel's trumpet). Any other suggestions?
posted by Rula Lenska to Home & Garden (5 answers total) 1 user marked this as a favorite
How did you get them to start from seed? I tried every method in the world (soaking, nicking, soaking and nicking, prayer, burnt offerings) this past summer and got nothing. Not even a sprout.

I had a fence full of morning glories though. Leftover self-sowers from seeds that my mom planted years ago. And I didn't do a thing. The area just got more water than in previous years. Maybe they like neglect?
posted by elsietheeel at 9:14 PM on January 25, 2011

Response by poster: Elsietheeel, the most reliable method for me is to fill a cup with the hottest possible tap water, drop in the seeds, and let them sit (or float--some will float) overnight. Then I place them between a couple of layers of wet paper towels on a plate. I place the plate pretty much anywhere I will see it and remember to keep the paper towels very damp (not floating in a puddle, but not ust barely moist). (I realize this is sounds overly granular and obsessive. But I have become obsessive about this damned vine, obviously.) Unfold the top layer of towel every couple of days, and you will eventually see the seeds wrinkle, then split and sprouting. At this point, plant them and keep the medium in which you planted them moist but not soaking wet. and you will have seedlings within a couple of weeks.

(God, just re-reading this before I post it makes me feel exhausted. Can't I just buy the damned plants already in bloom in, say, July? Sadly, no. If I could have found them, I would have done so.)
posted by Rula Lenska at 12:05 AM on January 26, 2011

I've been using these plants a lot lately, and your question made me curious. Your Seattle garden is in the same USDA zone as most of the landscapes I work in, but I guess that's not the whole story.

Charleston, SC and Seattle are in the same USDA hardiness zone, but...

Searching around briefly on horticultural forums, my guess would be that you need a much longer/hotter growing season than natural conditions will produce. Dave's Garden has recommendations for growing this flower from people all over the world. (scroll down to comments) Since you have access to a greenhouse, I would definitely start them ASAP then transfer them outside when they've gained some height and it warms up.

But I'm sure it can be done, a lot of the Dave's Garden people are working from places a lot less conducive to growth than you, and they seem to have success. (and sorry I have no recs for night gardens where you are!)
posted by Kronur at 12:17 AM on January 26, 2011 [1 favorite]

I wonder if it really gets warm enough where you are. They are really a tropical perennial used as an annual here. Lots of things are, like petunias. Moonflowers will grow in New Orleans, but I still have to nick the seeds and soak them in a bowl of warm water overnight. I plant them out when the soil gets warm, keep them watered and wait a long time for sprouting -- they also take a while to get big enough to bloom. The long growing season helps and they like the humidity. It might help to start them indoors early and transplant, especially if you use peat pots or something that keeps them from being too disturbed by the move.

Dig in compost and some slow-release super bloom fertilizer where you're going to plant them, provide something for them to climb on from the beginning and make sure they get plenty of sun and water. I also notice that not every vine will bloom but I don't know why. If you have warmer microclimates in your garden, try them there. (I once kept a stephanotis alive for three years sheltered next to a warm wall. It even bloomed, although we're way too far north for stephanotis, so you don't have to give up even if you're not in the right USDA Zone.)

Good luck.
posted by Anitanola at 12:31 AM on January 26, 2011

I live in Bucks County, PA. I've only ever grown moonflowers outside. They are certainly late-bloomers. We watered them all summer long and although the vine grew nicely, the buds didn't come until August or September, as I recall. As others have said, you may not have a long enough or hot enough growing season for them. I hope you can succeed, because they are such beautiful flowers and smell so wonderful.
posted by Guy_Inamonkeysuit at 6:09 AM on January 26, 2011

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