Pruning

Let's discuss pruning.  There are so many theories out there, I feel that I should share mine.   I had a professor of tree fruits in college who always said two things.  If you asked him,"When is the best time to prune professor?" He would respond, "When the saw is sharp." This response is good for the most part.  For most plants it really doesn't matter when you prune.  There are some plants like Oaks that should only be pruned when its cold so you don't run the risk of catching Oak Wilt. There are also some plants like clematis that have to be pruned according to what type of clematis you have, and some plants that should be pruned right after blooming, like lilacs and forsythia.  There are some plants that are easier to prune in the late fall or early spring because its easier to see what you are doing when there are no leaves on the branches.  You should avoid pruning in summer due to heat stress and you should avoid pruning in late summer because you don't want to force any new growth that won't harden off in time for the winter.  But all in all most of these things are not life threatening with the exception of the Oak Wilt, so he was basically right that you can prune when the saw is sharp. If you asked him, "How do I know when to stop pruning on my apple tree?" He would say, "When you can throw a cat through it."  I never really liked that one because I like cats but it made me remember it and it makes sense.  I have heard other people say, " When you can throw a basketball through it." but in the case of a cat you have to picture them with all four legs out stretched and their claws grasping at anything within reach.  If you prune your apple tree enough to throw that cat through then you have taken off enough.  The reason we prune our apple trees that way is three fold.  Number one is  reducing the amount of branches an apple (or other fruit trees) have increases the amount of light that gets to the developing fruit. Number two reason is that less branches means better airflow and less disease.  Number three reason is that you eliminate the branches that are growing vertically and leave the strong horizontal branches which gives the fruit a better flow of nutrients within the tree and it reduces the amount of branches that produce fruit.  Instead of getting a lot of small fruit you get a smaller amount of large scrumptious fruit.  A fruit tree is not going to win any beauty awards for aesthetics but it may for fruit production.
     Another type of pruning I want to address in this article is called renewal pruning.  Any multi-stemmed shrub like viburnums, lilacs, forsythia, dogwoods, witchhazel, deutzia etc etc. can be renewal pruned.  What this means is you take 3-4 of the heaviest oldest stems out at the ground level.  Every branch on a plant has a hormone at the tip of the branch that controls the growth of the buds behind it. When this hormone is removed, the rest of the branch says, "Oooooh I can grow now!!" So it does.  So if you prune at the tips of the branches all the time that is where you will get the growth and soon your plant will be top heavy and look like a woman holding her dress up with her skinny legs beneath.  If you prune at the ground level you will get new growth at the ground level and thus you are renewing your plant.  If you do this every year you will always have new growth at the bottom which will keep the plant full.  Removing the oldest stems will also reduce the height of the plant, and it will also keep the natural form of the plant.  Renewing a plant also helps in insect control.  Most borers will only attack a plant that is under stress.  By keeping the plant young you are reducing the stress and the borers will not attack.  Unfortunately this does not apply to Emerald Ash Borer. If you have a specific pruning question, I would be glad to answer it. 
Happy pruning.