Yellow ones are no different than orange in this respect. Trumpet vines bloom on NEW wood. Anything you can do to deter excessive green growth will help them bloom. No added nitrogen, no excessive watering. Root competition from grass especially(as they use up nitrogen) or other plants is a good thing. I would not purposely cut them back to the ground, as this would spur fast green growth. Yes, there might be maturity factor also. I was going to say trim the roots, but that would probably produce new sprouts(and new plants) from the ground where you cut any large roots.

I wonder if bruising the woody stems in the early summer would inducing flowering. The theory is that by doing so, less nutrients, chemicals, hormones or whatever is translocated through the stem, slowing growth and encouraging flowering. This is where the "beating your fruit tree with a bat" cure for the same problem comes from. I would never do this with a fruit tree, as bruising the trunk could cause a fatal canker or other disease infection. However with trumpet vine, I would consider a few vines expendable.

Rick

Rick, I know that for wisteria, which has a reputation of being very slow to bloom for some plants, root pruning is one of the suggestions. I think the theory is the stress causes "encourages" the vine to start blooming.

Just FYI...not sure if it would work here.

I also found several anecdotal reports on the web that it can take a few years to bloom, especially the year after being transplanted.

StPaulite, is it getting at least 6 hours of sun per day?

It easily gets 6 hours of sun a day. So I don't think that's the problem. I've contained its roots by having it in a large plastic container with the bottom cut out of it. So far, I haven't had problems with suckers popping up. I also hoped that this would help keep nitrogen away from its roots. Since it hasn't bloomed, I have no idea if this is working.

I'm willing to give it another year. I'll try root pruning it and/or bruising it to see if this does the trick. Since I've only got the one, I won't be too sad if goes south. There are so many other vines I could try...

Thanks for the advice.

Since the roots are already contained, I doubt root pruning will do anything, but it can't hurt.

Someone had a great one they recommended last year, but I didn't earmark it. Recommendations, please?