Mountain Ice Plants

How to best care for a perennial?

I bought 3 Table Mountain Ice Plants from Pahl’s back around May 12th. I kept them outside on my screened/covered porch for the first 2 weeks and planted Memorial weekend. The plants were still green and looking quite healthy when I planted them. I have been watering them regularly and fertilized as instructed upon my purchase. The plants continue to get smaller, brown, and are dying. What can I do to save them? These are the only plants I am encountering problems with. Please help!