I had a strange occurence on three new plants bought from 2 different local nurseries.

First, a chocolate mint plant, in a plastic pot (to keep it under control)- the leaves all turned dark black shrivled up and died...with immediate new growth underneath. It came right back full and healthy.

Then, I got 2 Penny Mac hydrangeas...I was at first unsure if they really Penny Macs as my other one had small flowers and this one was covered with bigger flowers. I got them home and planted them. We were gone for a coupe of weeks, but the plants got plenty of water. When we got hoe, the plants looked stressed and the leaves were turning dark black and shrileing. I decided to try some renewal pruning and when I started to cut back, the bushes had tons of new green growth. Both are doing fine and new bloos are coming (PM is a rebloomer)and the blooms are closer tot he right size. Do you think this could have been caused by the grower pumping the plant with fertilizer to get it to bloom big and early for sale?

thanks!