I spent several hours last week pruning around 400 feet of hedges, and several other shrubs that I keep shaped into spheres at my church, and it was the absolute perfect time to do this task. Here’s why…
Plants in our yards that require seasonal pruning to keep them to certain sizes or shapes (because that is their function in the landscape) go through growth cycles. It begins in early spring with soft, tender new shoots that can grow anywhere from a few inches to a few feet depending on the growth habit of that specific plant. The timing for controlling this growth should not be a function of when we get around to it, but rather based on when that growth is still tender and easily cut. If we prune too soon, the plant will fight back and put on a second flush of new growth. If we wait until the new shoots harden off, to the point of getting woody, then it will take a lot more effort and the plant will look more “hacked”.
The next two weeks are prime time for shearing because the new growth on most broadleaf shrubs, like laurels and burning bushes, is tender enough that it cuts like butter. By waiting another month, those new stems will be a quarter-inch in diameter and a lot longer, which all adds up to more debris to stuff in your yard waste bin.
Obviously not all plants grow at the same rate, so we need to pay attention to their stage of growth and plan our pruning accordingly. Boxwoods and Japanese holly, two evergreen broadleaf shrubs that are used a lot in our landscapes for lower hedges, are still several weeks away from needing their spring trim. Likewise, many conifers (needle-leafed evergreens) like yews and cypress, probably can wait until the end of June. So it’s not “one size fits all” in the garden - that of course would be far too easy.
If you have dwarf pines in your landscape, like Mugo pines, now is the time to cut back their “candles” before the needles start to elongate. By pruning now, the pine will continue to grow just enough to camouflage all your cuts and no one will be the wiser that it was ever pruned.
Although not a shrub or hedge, winter blooming heather should be sheared back this month as well. An unshorn heather plant will quickly become straggly and eventually die out in the center, whereas a seasonally pruned one will look tidy and be uniformly covered with blooms the following winter.
As rhododendrons finish up their bloom cycles and new growth pushes out, this is again the perfect time to direct their shape and size (while removing, aka “deadheading”, the spent flowers). If you want a bushier and more compact rhodie, simply pinch off the single new shoot at the end of the branch and 3 shorter ones will replace it. This strategy works very well when done now, but don’t wait until summer or you will be removing next year’s blooms.
As a side note, by half-way shearing back tall-growing perennials, like asters and chrysanthemums, you can keep them more compact and reduce their tendency to flop over when they finally come into bloom later in the summer. Also, placing a “grow-through ring” over them now is a lot easier than trying to corral them back into an upright position after a summer rain storm. We’ve all been there and it can be demoralizing.
So, there is much to do in the garden in May, starting with shearing those shrubs and heather. Until next time, stay safe and keep on gardening.
