agapanthus isn't really a tropical, it's a mediterranean plant. What do you mean many days in the 90's? here, a cool day is in the 90's :D But I don't think it's the heat, I'd repot your agapanthus in well draining soil and then WATER IT WELL, then it dry out... here agapanthus doesn't need much water even in days of 90º Maybe if it was like 110º you might water it more than once a week.
But I'd repot it. :o) Hope this helps.

Hello Lynn, forgive me for questioning you but are you absolutely certain your plant you have 'rooted from a cutting' is actually an Agapanthus??? When you say 'cutting', was it a 'division' of the root/bulb mass or a 'stem cutting'?? The reason being is that an Agapanthus is a bulbous perennial lily type of plant, that as far as I'm aware cannot be propagated by a cutting, only by seeds or division of the clump of bulbs. Have you a picture of your plant or its parent, that would really help. Agapanthus do have flowers in shades of blue/purple/white in rounded umbels with long strap shaped leaves that grow from bulbs. Hope to hear from you.
Gill.

Gill I was wondering about the same thing. I have some blue agapanthus that bloomed for the first time this summer. I'd started them from seed several years ago. I allow them to go semi dormant inside over the winter. I keep them in a cool place and give them very little water. They are all in containers. We were in the 90's from May through most of Sept this year.
Karyn

I would agree with Karyn1. They "melt" in CA when we get temps around 25F or so. Dry and cool in your climate, unless you have a heated greenhouse, would be the way to go.

Lynn, just wondered if you were out there.....have you got a pic or any more info on the 'AGAPANTHUS' for us??
I have agapanthus in my garden here in the UK and they flower for me OK so I am still wondering what you actually have got.
Gill.