GARDEN THERAPY: Pruning—Loud and Proud – May 2022

By Mel Bellar

In my humble opinion, pruning is what separates an OK garden from a really nice garden.  Truly, I believe that pruning is an important aspect of making a garden look good and I promise, it is not that scary. Side note, it is not pruning unless you are dealing with a shrub, tree or woody vine; you don’t prune perennials or grasses: you cut them back or dead head them.

Pruning is a marriage of simplicity and forever complications. The subject provides way too much to cover in a single column, so I am going to shoot for the simplicity for now. The first thing to know about pruning is when to do it, and that depends completely on the shrub or tree and if, and when, it blooms. While I am pretty irreverent about the “whens” and “whats” of gardening, opting more for the “when I have time” approach, even I don’t want to prune the rhododendrons before they bloom. Basically, some woody plants bloom on new wood (this year’s new growth), some bloom on old wood and some have insignificant blooms. Generally, it is good to prune when plants are dormant, meaning the late Winter or early Spring, but that is not the case with Spring and some Summer-blooming shrubs and trees.

Here are some of the Spring bloomers (that grow in our area) that you should not prune until after they bloom:  lilacs, rhododendrons, weigelas, mock oranges, fothergillas, forsythias, flowering quince, magnolias, dogwoods and viburnums.  Ninebarks and smokebush also fall into this category but sometimes I go ahead and prune them anyway if they are misshapen or are getting too big. This is only because I grow them for their foliage and don’t care that much if they bloom. I am sure there are more, but hopefully I am not forgetting something major.

There are many deciduous woody plants that bloom on new wood, and these can be pruned in the late Winter or early Spring.  Some of these include our main hydrangeas (the arborescens and paniculatas—not the blue ones!),  potentillas, most spireas (check first) and Rose of Sharon.  Most fruit trees should be pruned in late Winter or early Spring but there are a lot or rules and methods to get different types of fruit trees to bear and that is way beyond the scope of this gardener and this column. We only prune fruit trees for shape and general effect. Doing that in the early Spring works well.

Pruning can get very complicated when you are trying to rejuvenate an old tree or optimize for flowering on certain plants. This can require a multi-year plan and much more detailed knowledge and observation. On the other hand, what we do most of the time is pretty simple and very effective. The basic goals are to keep the plant healthy, attractive and the right size. The latter is not always easy if the plant is naturally the wrong size for its location, but it can be managed for a while.

Generally, some shrubs have a worthwhile branch structure that you want to see, and others do not. Go ahead and use the hedge clippers on the unstructured ones, like potentillas, boxwoods, most spiraeas and Annabelle hydrangeas; I would almost include weigela in this category. Just to be clear, we would call this shearing and not pruning.  If you use hedge clippers on other shrubs, I may have to turn you in for crimes against plantdom (just kidding—they are your shrubs).

Here is my simple formula for pruning woody plants.  Decide what you goal is: Is it size reduction or, rather, improving the shape or appearance? Start with cutting out any dead or damaged wood and then move on to crossed branches or branches that are rubbing. These not only look bad, but they also leave wounds for insects and disease to get it. Next, start taking out branches that are pointing inward and in awkward directions, and start cutting the branches back to the size you envision. Make sure that you cut the branches just above a node where you would like new branches to form. If you don’t cut right above the node you will have “fish hooks” (extraneous dead nubs sticking out from the new branches). It is hard to avoid leaving some fishhooks space, but we try not to.  Keep cutting and standing back to see how it looks until it is the right size and pleasing to the eye, like you would imagine if you were to draw a perfect version of that shrub. Don’t worry! It is hard to make a mistake that won’t be corrected by the new growth in a few months.

There is so much to say, but this will have to do for now. Go out there and pick a shrub that is not a centerpiece or your favorite and give it a try.  Practice is the best way to get good at it.

Mel Bellar is the owner of Zone4 Landscapes and a passionate
Andes gardener.~