I'm sure it depends on which sunflowers you use, but I know for a fact that people grow morning glories on tall sunflowers. I read a book entitled "Sunflower Houses" that is a collection of garden memories from peoples' childhoods. One memory was of growing a sunflower house by planting sunflowers in a circle and interplanting Heavenly Blue morning glories so they would climb on the sunflower stalks. When the sunflowers were tall enough, the tops of the sunflowers were pulled together with twine to make a roof. I've wanted to recreate that since the first time I read it. I've not had the space or enough sun, but I might be able to pull it off this year.

Hope that answers your question.

Martha

I don't know about Morning Glories, but the Moonflowers I've grown were very robust and more then covered a 10 foot arbor. I would think that they would be a little much for Sunflowers no matter how tall the Sunflower. A heavy summer rain would only add to the problem....Maryl

Moonflowers, or Ipomoea alba, are a much heavier vine than regular morning glories, I. nil, purpurea, or tricolor. I would wonder about whether the Sunflower stalks would be strong enough to support them, too. At the very least, one vine is all I would grow up a single Sunflower.

I am going to try to grow some Japanese Morning Glories up my last years dead Sunflower stalks. I think they are sturdy enough to support MGs. They are pretty tough. These were a tall Sunflower variety that self-sowed from a bird seed mix. They branch a lot, but the main stalk is huge and about 8-10' tall (I have several standing). I might have to remove some branches and use some strong jute to twine around several stalks that are close together.

If they look like they are not going to hold the vines, I will set some conduit in the ground to provide more support. Conduit is pretty cheap - about $3 for a 10' length at Lowe's or HD.

Susan