We live outside Philadelphia, PA and had two Nandina planted in the fall, about 1.5 square feet each at planting. They did beautifully through the winter, and then lost many leaves with some very cold weather. They started to grow in the spring, but now they seem to be stunted with many very small leaves towards the bottom, and aren't bushy as they used to be. A few of the leaves have some yellow/brown discoloration. I fertilized them with a small amount of all purpose fruit and vegetable fertilizer about a month ago and have been watering them once to twice a week in between rain. They are located in a spot with poorly draining soil-it seems to be more clay to me but there are plenty of earthworms and the like in there. They are mulched about an inch with the mulch pulled away from the base some. How can I get them to grow more? Should I try digging them up some in a mound above the damp soil so they drain better? I can post photos in the morning. Thanks!