Example of a thinning cut made to peach. The cut is made directly above a side branch going in a preferred direction or a smaller one that will help to reduce the size of the plant. Q. We have two fantex ash trees, 15 years old. They are spreading out too far. How far can we cut them back without killing them? A. The problem with ash is that it does not have much ability to come back from cut limbs if you cut back too far. You can begin structuring the tree if you do it fairly early and stay on top of it but if you let it go too long and then cut it back you may have some problems.               You can cut it back to side branches that are growing in a desirable direction but you cannot prune it back by what we call heading cuts (stubbing it back) and hoping these dead end cuts will resprout. You can cut back into about second or maybe three year old wood (there are still side buds remaining that can grow) but if you cut into a limb with no buds present it will probably die back to a major limb.             So cut back to a branch at a crotch going in the direction you want it to grow. When limbs are growing the wrong direction, eliminate them back to a crotch or another limb. Do not leave any stubs (dead end cuts). The Modesto ash on the right was “topped” and because of the nature of ash it never came out of it but had to be removed. The one on the left was cut back early enough so that it could resprout from young wood. Consequently the one on the left developed swellings just under the cuts that are full of tissue that can generate new growth. The one on the right could not.             I hope this makes sense. I attached a picture of a thinning cut made removing a larger limb going up…to a smaller limb going out and toward the camera. The direction of growth of the limb was changed without leaving a stub.