Hibiscus flowers not opening

[moira mount]

I have two Hibiscus bushes, one is a crimson double with a white centre and a pink double flower one, the pink one is full of flowers and no problem but the crimson one comes into bud but the flowers will not open fully, they just partially open. I bought this plant from a garden centre two years ago and kept it in a pot, the same happened then so i transferred it into the garden where it has shot up in height and is snided with flower buds. The two bushes are about 3 feet from each other in the same patch of soil. I have had Hibiscus bushes at my last house and have never had problems, can anyone help solve this problem. I have checked in the flowers for grubs and pests but cannot see anything on the flowers or bush

[gardening_guru]

Hello Moira,

If possible, can you give me the full names of these Hibiscus, I'm assuming that they are cultivars of the hardy Hibiscus syriacus?