Don’t make pruning more complicated than it needs to be

Gardeners like to make things more complicated than they need to be. I can’t explain this phenomenon, but we seem to be resistant to the easy approach to most things.

Pruning is a great example. Somehow we’ve managed to make pruning an almost mystical activity, only to be done during a waning crescent moon, with cuts made at a 32.3-degree angle exactly 3/16th of an inch above a bud, with medically sterilized tools and special arborist eye protection.

I kid, of course, but we do make it out to be a big thing, although I admit some pruning is a little confusing. I own three books on the subject and typically consult at least two of them before I go near a fruit tree, and in the past two years I’ve attended three webinars on the subject.

I typically advise a “What’s the worst that can happen?” approach to most pruning jobs. The answer is usually that you won’t get flowers or fruit, and while that’s not a great thing, you usually get another crack at it the next year.

For most flowering shrubs, it’s important to know if it blooms on last year’s growth or this year’s growth. The earlier in the season a shrub blooms, the more likely it is that it blooms on so-called old wood.

These plants, which include a long list such as lilacs (Syringa), weigela, ninebark (Physocarpus), forsythia and mock orange (Philadelphus), should only be pruned (if necessary) after the blooms fade. They will have time to put on new growth in summer, which will produce next years flowers.

Other shrubs bloom on new growth, and typically later in the season. These include roses, butterfly bush (Buddleia) and rose of Sharon (Hibiscus syriacus). They can be pruned in spring, and sometimes all the way back to encourage fresh, strong growth. It’s best to do this in spring as leaf buds begin to swell.

And a final group of shrubs blooms on both last year’s growth and new growth. The best example of these is the big-leaf hydrangeas (Hydrangea macrophylla) and mountain hydrangeas (Hydrangea serrata). Ideally these aren’t pruned at all, other than to deadhead old flowers, as you’ll be sacrificing a flush of flowers by pruning at almost any time.

Rather than memorizing what shrub gets each type of pruning, a bit of careful observation can tell you which type of pruning might be appropriate. But if that fails, you can fall back on the “What’s the worst that can happen?” adage and opt for the safe approach of not pruning at all or pruning some and seeing what happens. You might lose this year’s flowers, or you could end up with floppy growth, but it’s unlikely that you’ll kill a plant.

Of course, you could always look up the appropriate way to prune a specific shrub. Once you know it you’ll start to recognize the signs of how a plant wants to be pruned even without knowing exactly what it is.

And I will personally guarantee that it will be OK, even if you prune during a full moon with cuts at odd angles. Because it just doesn’t have to be that difficult.