Heavenly Blue Morning Glory No Blooming

Asked September 17, 2018, 4:30 PM EDT

My Heavenly Blue Morning Glory vines look the best they have ever looked, but they're not blooming. Can you tell my why they're not blooming and what can I do to encourage blooming or is it too late.Thank you!

Macomb County Michigan no flowers morning glories

3 Responses


This is frustrating, I know, as mine are not yet blooming, either.

First, do not fertilize anymore, if you have been. Too much nitrogen produces only leaves.

Morning glory sets flower buds depending on a combination of temperature and day length. Here is an explanation —-

“Short-day plants (SDP) flower when the days are relatively short (generally nine hours or less), such as in the late fall or early winter. Long-day plants

(LDP) flower when the days are relatively long (generally fifteen hours or greater), as would occur in late spring and early summer. In day-neutral plants, flowering is not regulated by day lengths. In other words, day-neutral plants flower regardless of the day length.

A plant may respond to a certain day length at one temperature but exhibit a different response at another temperature. For example, both the poinsettia and morning glory are absolute SDPs at high temperature; however, they are absolute LDPs at low temperature and day-neutral at intermediate temperatures.”

Another study showed Heavenly Blue only flowered, with short days = 10 hours light or less, in these temperatures——

Short days at 70-75F

Short and long days at 63-65F

Long days at 55F

Considering the temperatures this summer, I suspect your plants will be reacting as Short-day plants. And, we may soon be having intermediate temperatures which in time can switch them to a day-neutral state. You should be seeing flower buds soon, perhaps as soon as a week or two. One other consideration- some studies show that short day plants will not flower if their night time darkness is broken by brief exposure to light at night. So, if your plants are receiving light from a porch lamp or street light, this could prevent or delay flowering.

Here is an idea from my personal experience—last year my Heavenly Blue m.g. began setting lots of flower buds in early October, just as night temperatures were about to fall so low as to kill them(light frost). Before that happened, I cut long vines full of buds off the main plant, brought them inside and placed them in a large vase of water, draping the vines over my plant stand in the kitchen patio door. They bloomed and I had beautiful m.g.s into early December!

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Thank you so much for your reply and excellent advice, Laura. I am just now seeing buds starting to appear on one of the vines. I hope I'll see blooms soon before the weather changes.
Nancy McGuire

Nancy, You are very welcome. That’s Great, mine are setting flower buds, too! I plan to start seeds early, indoors next year and see if I can get them blooming next summer. I’ll use peat pots because they don’t like roots disturbed when transplanted.