Are you sure that it is well watered? It seems to me that it needs more water.

Is it a moon flower vine? My looks wilted during day sometimes, if it is really hot, I just give it more water
right down at the roots.

Greetings,(umbrella)
I can think of another reason if more water doesn't work.
You mention that its in cement, how new is the cement?
Is there a cement grout in the brick work?
the cement could be combining with any fertilizers that you use on it, if you increased the fertilizer because it was wilting, it would wilt more if this is the cause.
The lime in the cements can cause a chemical burn to the roots if the fertilizer mixes with it.
Thats why we never fertilize and spread lime at the same time!
I'd say stop any fertilizers (even organic) and increase the watering, by soaking the roots down deep, to see if that helps.Moonflowers do wilt some but always seem less wilty when the rains satisfy them. Hope this helps!

surre sounds like it needs more water to me also.. it's amaising the ammount of water they need... I can water the planter mine are in .. long deep and quite thoroughly in the morning .. and by afternoon.. they are drooping... guess it's time to get the watering system up and running... Gordon

I never noticed before, but this year my moonflower vines wilt in the heat of the day and get ok again in late afternoon. They have plenty of moisture as we have had rain showers this week everyother day

Has anyone tried spraying the leaves? I’m afraid to over water and get yellow leaves. Mine are on a 3rd story fire escape in full sun so they get very hot and wilted! They’ve already climed a full story onto the fire escape above.