i recently built two rock planters around two feet deep. I filled the planters with very little native soil and the rest just regular ol top soil. I planted a beautiful huge yellow dahlia in each and surrounded them with verbena etc. My question is this; my dahlias are drooping quite a bit. It has been very warm here in the inland san diego area so I don't know if it is too much water that is making them droop or what. I would assume with so much top soil that they are planted in that it will retain the moisture needed.

Anyone have a solution to why my dahlias are drooping?

Thanks in advance.