I am growing periwinkle (locally known in Middle East as Vinca) in a very very hot climate and in full sun.

Whilst not dying, some of the plants have become very leggy. How do I prevent this? Should I cut them back?

In addition, I am growing Periwinkle in ceramic pots outside. These plants are really struggling and I think it is because the pots are heating up and burning the roots. I had thought of putting the plants in plastic pots and then inside the ceramic pots. Would this help? I could even wrap the plastic pots in damp tea towels in the ceramic pots to keep them damp and cool in the day? What do you think

Or I could just forget the whole thing until after the summer - another 2 months from now! I really don't want to select this option

Thanks for your help: