bought a few hibiscus last fall, placed them in pots and kept them inside the house over the winter, they did well, their leaves were healthy and by mid winter, some started droppign their leaves (yeloowhish), but then new growth came up within a week or 2, or as they started falling new growth would come out.

I took them ouside late may, nights were about 60s or mid 50s. nothing bad, but just recently, like mid june, one by one stared having yellow leaves and no new growth has come out, and now has no leaves at all. they are about 3 (that i bought last fall). on the other hand, i have 2 more that one i had for about 5 years and another for 3, they are fine. so this discards the possibility of a pest. I just don't understand it...it does not follow a pattern. One of them started to have a small branch of new growth, but it just turned yellow (very small leaves) and seems dead now !

3 total.

Any suggestions? ideas? advise?