Twice a year, once in the spring and once again in the fall I teach a class here at the nursery on the basics of pruning. It is a free class and lasts about an hour and it is always well attended, not because I am such a fabulous teacher but rather because pruning is one of the great mysteries of gardening. It is the single biggest source of anxiety amongst gardeners and it is my task to remove the angst.

If you’ve got questions about how and when to prune your rhodie that now blocks the living room window, or your apple trees that are loaded with water sprouts, or the wisteria vine that has engulfed the arbor you so carefully constructed for it, or your hydrangeas that never seem to bloom, or whatever your concern might be, this is the class for you. It is this Saturday, November 8, at 10:30 a.m. Here’s a little preview of what you will learn.

The real secret to proper pruning is in understanding how a plant will react to the cut you make on a branch. “Where” you make that cut and to a lesser degree “when” will determine how the plant will respond. There are only two kinds of cuts in the pruning world: thinning cuts and heading back cuts. Understand how a plant responds to these cuts and you’ve got pruning figured out. It’s that simple.

A heading back cut is where you cut off the end of a branch or stem. Doing this causes lots of branching and growth right below the cut. When you shear a hedge you are essentially making heading back cuts. These kinds of cuts are perfect for plants where you want lots of dense, bushy growth. Unfortunately, what happens in a lot of yards is that the man gets out there with his power shears and starts heading everything back once a year. It only takes a few seasons before the yard starts looking like a miniature golf coarse. Heading back cuts destroy the natural branching patterns of plants and ultimately leave you with a yard full of green meat balls.

A thinning cut is where you completely remove a branch down to where another branch is growing. Thinning cuts are much less traumatic and don’t cause the rampant re-growth that heading back cuts do. This kind of pruning is perfect for most trees where you want to work with the existing branching pattern. Your goal with thinning cuts is to remove selective limbs to open up the tree and let in some light, enhance the form, or gently reshape the plant so it isn’t growing where it shouldn’t be like on the roof or into the gutters or over the driveway.

Armed with the above information you should be able to approach a shrub or tree and know how to proceed. Always prune with a purpose. What is your objective? For a fruit tree it is optimal fruit yields and quality. Form is secondary. For a shade tree form is everything. For a tree like a flowering plum or cherry it is form first and flower production second. For a vine like wisteria it is all about the flowers and for a grape vine it is all about managing the fruit set. There always has to be a good reason to prune and getting a new chain saw for Christmas doesn’t qualify as a reason to go out and massacre the yard.

In addition to knowing where to prune, knowing when to prune is also important. Again, this depends on your objectives. You can do what I call light pruning almost any time of the year. But if you have flowering plants like rhodies and azaleas or winter blooming heather or summer blooming roses and hydrangeas then timing is everything. Prune at the wrong time and guess what? You may not get any flowers.

Generally speaking, if a plant blooms early in the spring before it starts growing new foliage then you should prune it right after it finishes blooming. Then it has the rest of the year to produce new flowers for the following season. Never prune it in the late summer or fall because you will be removing potential flower buds.

If on the other hand your plant blooms in the summer on the ends of the new growth then you can prune it at the beginning of the season. Roses are a classic example of this kind of plant. We prune them hard in the spring which stimulates lots of new growth which in turn produces lots of new flowers at the ends of that new growth. Butterfly bushes are another example. Hydrangeas however don’t follow this rule. You’ll have to come to the class to find out how to deal with them. See you on Saturday..

Steve Smith is owner of Sunnyside Nursery in Marysville. You can reach him at 425-334-2002 or email at info@sunnysidenursery.net.