With my husband being a big fan of cherry pie and my favorite jam being cherry, 2010 was an exciting gardening year for us.
Pruning Cherry Trees
After 4 years of experimenting and moving things around and some flops and some successes, we finally had our long-term garden plan in place and the decision of where to plant the sour cherry trees was made. I researched and picked out the varieties that best fit our needs and that fall, he drove to a nursery over an hour away to buy the trees. A few days later our boys helped me plant them. And we were done! We just needed to be patient and wait for the annual battle with the birds over the cherries. That's what I pretended to believe, anyway, because the idea of pruning a tree was completely intimidating to me. A tree isn't like a plant, which will usually recover in a short time or, worst case, leaves you out only a few dollars if it doesn't recover. Trees are expensive and slow-growing so mistakes are a more serious matter.
Knowing pruning was inevitable if we were going to look forward to many years of healthy trees, I began my research. The amount of information available was overwhelming and the variety of opinions only added to the confusion. I quickly passed the pruners on to my husband and asked him to do the deed.
Pruning the cherry trees is not a one-time job. They need much attention the first few years of their lives to ensure they grow in a way that gives the proper structure for strength, air flow, and light penetration when they are mature, so I have since sat down and and invested more time in research. I made a few discoveries in the process, things that have made me feel confident that when the time comes, I will be able to make those cuts. I've made a short list summarizing the things I felt were the most important points to prevent me from over-thinking the whole process when it is time to prune.
Where to learn about pruning: I found that pruning instructions offered through university extension programs are typically the most straightforward, without obvious personal opinions that can make a novice doubt their ability to ever be informed enough to complete the task. It allowed me to focus better on just the basics.Many of them also use simple illustrations which make "seeing" the things we're supposed to cut with pruning shears and the direction we should be cutting easier.Probably my favorite illustration can be found by following this link and scrolling to page 2. The simple silhouette and many of the tree pruning features you read about all appearing on one tree make it a great reference for quick learning.
When to prune: At the time of planting, all dead or diseased wood should be removed. One of the things that I found to be most contested, though, is when you should do major pruning of them. There are the winter pruners and the summer pruners. Summer pruners believe they have a better chance of avoiding disease. They also encourage slower growth of the tree, which is helpful for mature trees. The winter pruners encourage more rapid growth as they are not interfering with the tree during the time it is actively growing. Waiting until late winter, right before it emerges from dormancy should help with avoiding disease. I also found some combination pruners! They do the major pruning in the winter but prune away things like water spouts (thin, leggy vertical growing shoots) in the summer.
Knowing where to begin: Cherry trees benefit most from central leader training. This means one main trunk is chosen and 3-5 lateral branches are selected as the scaffold branches. These should be as evenly space around the tree as possible, not directly across or above/beneath one another, and should have 18 to 24 inches of vertical space between them to allow good airflow and light penetration as the tree grows. The crotch angle (the point where the branch meets the trunk) should be at around a 60 degree angle. Since cherry tree branches tend to grow vertically you may need to put metal spreaders in the branch crotches for a few years to train them to this angle. We had trouble getting these to stay in place and opted to tie the branches, close to the crotch, to stakes in the ground.
If you are starting with a whip, a young tree that looks like a stick with few or no branches, it will be cut back 1/4 inch above a bud that is 30-36 inches from the ground. Starting with a whip allows you be more selective about which branches to choose as your scaffolds as they begin growing from the trunk; However, since it is a very young tree, you have a longer wait until that first cherry pie. When purchasing older trees, keeping the idea of scaffold branches in mind will assist you with choosing the tree with branches that will be easiest to train.
How to cut: When you decide a branch needs to go, the whole thing should go. Do not leave long stubs. Leaving stubs causes slower healing times because the healing hormones that travel to the cut from the branch collar (the part where the branch and the trunk connect and are actually sharing wood) have to travel farther to the wound. And often, the stub will just die anyway. Cut it to 1/2 to 1 1/2 inch from the trunk, but not into the branch collar.
Similarly, if you are heading back branches, or shortening them, cut at about 1/4 inch above a bud. Hormones that heal pruning wounds also reside in the buds so, again, you don't want them to have far to travel.
Cuts should be made at an angle to prevent water from sitting on the open wound. You want to angle the cuts so that new growth will emerge growing in the right direction. You don't want to encourage it to grow toward the center of the tree.
What tools to use: Fiskars offers a large variety of tools for your pruning needs. Hand pruners can be used on branches up to 1/2 inch in diameter. Loppers can be used on branches up to 1 1/2 inch in diameter. Pruning saws can be used on branches over 1 inch in diameter. Pole pruners can be used on mature trees that have branches that are out of reach.
More extensive information about things such as how to determine which types of branches to remove, whether or not wound dressing should be used, etc. should be available through your local extension office, which can be located by following this link.