I bought this plant in spring with lots of flowers on. Since then it has had some leaves, although these seem to go brown and fall off. It has been very hot recently so I have watered it, but not too much.
Certified GKH Gardening Expert
Your plant either needs more water, or the roots are too crowded to get enough water or your soil needs to be amended in some way.
This article may help you identify the exact issue and correct it: