I live in a small town near Abilene Tx..(zone 7b?) It's HOT,dry and more caliche rock than native soil.And it is on the alkaline side.Nonetheless, I have the most beautiful healthy morning glory,and thunbergia vines I've ever seen in my 40+ years of plant fanaticism.Yes I must say they are lovely and I've had to construct a bower over my front porch area out of River canes since theres about 12 to 14" of growth daily..I am amazed and proud but so far have only gotten 3 Scarlett O'Hara blooms , nothing yet on the Thunbergia..I do not (have not) fertilized them except for some diluted fresh urine on occasion(1part to 10 water)This lush foliar growth smacks of high nitrogen type growth but I am certain my soil is 70% pebbles and hardpan.Any suggestions? I'm getting anxious being this late in the season.My instinct eants me to add some sulfur amd super phosphate...help!
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Hi, PlantwhispererKim550. to ATP!

The name of this morning glory sounds familiar; I'm thinking that I may have tried it once. If so, mine was very stingy on blooms -I think I got two before the plant finished.

You might try a foliar feed of bloom booster, just to see if it makes a difference.

to ATP.

PlantwhispererKim550!

What a glorious Morning Glory Vine! I don't think I've ever seen an MG so lush! Your first photo is really nice showing the entire plant and since the only photo in the database of Scarlett O'hara is a single bloom, I've proposed to move your photo over to the database.

Japanese Morning Glory (Ipomoea nil 'Scarlett O'Hara')

I agree with Chelle that you should try some *Bloom Booster* plant food and see if that helps.

Oh, if it's an I. nil, they do like to be fed! I grew some on my back porch one year (and have one growing on my front porch right now) and they took forever to bloom. I had beautiful lush foliage but no blooms for a very long time.....and then they went crazy. I went back and looked to see when I took photos of mine in bloom a few years back, and it was in September.

That's great news, Woofie!

Upon further reflection...I recall now that the one that didn't produce well for me was Sunrise Serenade. The ol' quick-fire memory cells aren't quite what they used to be!

Easy enough to get them confused. I get Sunrise Serenade confused with Crimson Rambler, too. Oh, and the I. nil I have on my front porch right now also has lots of nice foliage, but so far has only produced a couple of blooms. However, it is in a somewhat shaded area that mostly only gets afternoon sun.
You know, I was under the impression that Scarlett O'Hara seeds were hard to come by, but I see them being offered by Parks. I may have to give them a try next year.

PlantwhispererKim550 said: fertilized them except for some diluted fresh urine on occasion(1part to 10 water)This lush foliar growth smacks of high nitrogen type growth

Urine is a source of nitrogen. If you are not balancing it with other nutrients, then that might be your problem.