Usually this means too dry or too wet. Sometimes it can also indicate a nutrient deficiency, as when hollies are making new growth and an excessive amount of existing leaves yellow and drop at the same time. There is not enough nutrients present to sustain a full top so some of the oldest leaves are lost in order for the new growth to live. If your new trees cannot live in your existing soil in your climate then you will have to provide a different soil. A common way to do this in a simple way is to acquire more suitable soil, dump that on top of the existing soil and plant in the new soil. Where there is not a suitable situation for mounds or berms of topsoil then another possible solution is to excavate and replace the existing soil with better soil. This requires being able to remove and dispose of the existing soil. With trees quite a large area of existing soil needs to be dug out, preferably one as extensive as the entire potential rooting area of the trees. Never dig out a small hole or pit of soil and plant long-lived subjects like trees and shrubs in liberally amended or completely replaced backfill soil. On damp clay soils in particular there is a likelihood of the modified backfill causing the planting hole to collect water during wet conditions. This is due to the difference in soil texture between the soil within the hole and the soil around it. When plants are sitting in pockets of coarser material surrounded by less coarse natural soil there can also be a marked attraction of water to the finer soil during dry conditions. This is one of the reasons bare-rooting at planting time has begun to be advocated. Plants installed in natural soil with intact potting soil root-balls can be quite difficult to keep moist during dry weather, until they root into the natural soil.

Thanks everyone! When you say they will come back , do you mean from new sprouts at the bottom or will they bounce back from the old growth? I double checked and some are only half burned so My husband and I spent a couple of hours covering them. Unfortunately, all the Dynamites and Natchez are totally burned.

Good point rhizo, I was thinking the same thing. I usually dig a hole at least twice as wide as the root ball but not deeper, add a large bag of organic matter + a bag or two of coarse sand to the existing soil, depending on the size of the hole. Any left over soil I take to another area since its now amended & good soil. That crepe looks like a two bags of sand sized hole would be needed. Here in Oklahoma where we usually have a high clay content, the sand helps to keep the surrounding soil from packing down, allows air to the roots air and makes it easy to soak in water quickly and deeply. Roots spread much faster in it. I have added sand (along with organic matter) for years when amending my soil or creating a new bed because the soil stays moist longer, water soaks in much faster and the drainage is improved 100%. I buy a truck load when making a new planting area. Its cheap. I create a ridge around the hole to create a well. When watering, a hose set low to dribble is good and I only water when it dries out. A layer of mulch on top but not right up against the plant keeps the soil moist longer and I frequently check with my hand underneath the mulch. This post was edited by TexasRanger10 on Wed, May 21, 14 at 14:46

Natchez Crape myrtles develop a wonderful umbrella shape. And they naturally put out more trunks than other myrtles. The trunk density can be considered a form of screening. And the overarching canopy of the tree means that leaves will be hanging down to six or seven feet. The 'limbing down' method really does not look good. (I'm assuming you mean lopping-off large branches, for a 'layered' look) In fact, there's a name for it: Crape Murder. Here in Madison, being a Crape Murderer is equivalent to chewing gum with your mouth open. People will shun you. I suppose, considering that the trees are young, one could clip the outer tips of the branches, regularly, in the way that one shapes and maintains a hedge. That would be quite a chore, though. Me, I'd leave the Natchez totally alone, and let them develop their own architecture. And I'd underplant them with Magnolia Grandiflora, Glossy Viburnum, or a Clumping Bamboo (the kinds that don't send out runners). I wish you'd asked us earlier. There are other Crape Myrtles that assume the dimensions you're describing, all by themselves. Acoma looks like a miniature Natchez, except that it blooms more. On the more mature specimens I've seen, the leaves start at four or five feet - naturally. And I think Catawba would also grow within your desired dimensions. Again, I think that simply leaving Natchez alone, with no pruning at all, will allow it to develop the exaggerated umbrella shape which would yield maximum screening. However, aside from getting precisely the screening effect you'd envisioned, I'm guessing that you chose the right plant. A majestic tree like Natchez, if allowed to develop its own natural architecture, will give your property a scale and an aura that would be hard to match with another plant.