To minimize the stress on your perennials, you want to make sure you have your hole prepared that the plants are going to be planted into. Depending on the size of the perennial that you plant, you want at least a decent size hole that is about a foot around. You will have to adjust the depth once you've got your perennial divided. You might have to add a little bit more or a little bit less mix, but I'm taking out this old mix and I'm going to be putting in the new mix that I just made. I'm also going to be lining my hole with the garden gypsum that I had to help break up some of that clay soil. This soil that I have here I'm going to add to that mix that I previously made so that it's not so much of a shock when those roots get down into this soil. I'll actually take some of this dirt and add it to my other mix. The other thing that I will do is I'll presoak my hole with water so that it's nice and evenly moist. It also by doing this will tell you how well your hole is draining. If it doesn't drain within 10 minutes, you've got a serious clay problem and you might have to think about taking some other measures. You can see how this is pretty clayey here and it's not draining real fast, but you have to give it time to drain.