I can't comment on whether there is or isn't too much nitrogen in your soil.

Nitrogen can either delay blooms or bring them on, its a sensitive nutrient for the soil.

If it is too much though, it will dissipate, I would think, by the end of the month and you will have blooms.

I have some flying saucer that usually bloom earlier than now, and have had tiny buds on them for several weeks now. I just noticed today that one of them has shot up and is quite large now, ready to bloom in the next day or so and another one will not be far behind.

It's been a very strange growing season this year, extremely hot and humid for so long, with very little rain, if any at all.

so many things in the environment affect the growth of plants, and the weather is sure one of them.

I read somewhere recently that the tricolor morning glory are ones that grow best and bloom best in cooler temps.

that explains a lot to me about how my tricolor MG have bloomed over the past 5 years.

Tricolor include the heavenly blue, flying saucer, wedding bells, blue star, and a few others I can't think of the names of.

But about 5 years ago, they all bloomed very poorly for me, till late August and then they started and where lush and beautiful until the frost got them.

4 years ago, they did poorly all summer and fall with very little blooms. It was a hot summer and very warm fall, I was still picking tomatoes right up until thanksgiving on one remaining plant.

I gave up on them for a year and then tried again 2 years ago.

We had entire month of nothing but cool temps, rain and then some heat for a month and the temps got cooler, They where just spectacular blooms almost the entire summer and fall.

Last summer, well that was a lost cause on most of my MG. we had 2 solid months of rain, and cold. jackets needed well into the beginning of August and a couple of times it got so cold, I almost turned the heat back on again.

Not much in MG bloomed at all.

This year isn't a lot better in terms of crazy weather. Some of my MG have bloomed but most of them are just growing vines and barely showing signs of buds.
Others have done OK but not great.

Gardeners are at the mercy of mother nature and any and all curves she wants to throw at us.
All we can do is wait her out and hope for the best.

Fran

Fran has some good advice. Maybe the hot weather had a delaying effect on flowering and you will see flower buds developing as we go into September. Good luck, Heavenly Blue was one of my first vines to grow and is a fave.