Once beautiful Vigoro false spirea "Younique Carmine" was planted last year. I had to move it to a planter on my deck to protect it while fencing is being installed as I didn't want it trampled. Another spirea planted with it is doing great in its planter. But this one has leaves starting to curl and wilt although it still has still new growth coming out. I have cut the bad parts off the plant. Any suggestions as to cause and treatment?