Over the last few days, I’ve watched snow and freezing rain pile up all over gardens in my neighborhood.
How to Hedge: Planting and Pruning Guide
By Robin Haglund
Weighty winter messes like these are fast reminders of how hedges – big and small – can go dreadfully wrong when neglected or pruned improperly. Although sheared forms rarely illustrate natural plant forms, they can have appropriate and often beautiful applications. But, when they go wrong, it can require months or even years to recreate the beauty and function of these plantings. And, quite often, reconstructing a mature hedge not only takes years but also the cost of purchasing and replanting the plants themselves.
So how to get it right? Begin at the beginning:
- Pick the right plant for your location:
- Shade plants for shade; sun plants for sun. Big plants for big spaces. Small plants for small spaces.
- Evergreen or Deciduous: Rarely do deciduous plants fit the hedge bill every day of the year. Usually, the goal is year-round interest or privacy, so choose your plants wisely. Odds are, you’ll want something that doesn’t lose its leaves come winter.
- Big leaf or small leaf: Hedges are sheared frequently, and they’re cut in ways that can highlight where they have been cut. Big leafed hedge plants like laurels can look very sliced and diced even after a proper shearing. Small leafed hedge plants like boxwood seem to camouflage shearing much better.
- Space correctly when planting: Hedges are high-frequency maintenance plants. If they aren’t cut at least once or twice a year, they can lose their form and be difficult to re-sculpt. When they are planted, spacing is generally a bit closer than would be done if the plants were designed to grow to their natural shape and size. Each plant is different; however, large hedge plants like Portugal laurels, which grow to 30 tall and wide naturally, should be planted about 18-24” on center for hedgerows. (On Center refers to the distance from the center of one plant to the center of the next.)
Once you have designed and installed your hedge, its time to begin planning when and how to cut it. Timing your work is critical to keeping your hedge healthy. In areas with cold winters, it is very important not to prune your hedges in fall. Cutting can stimulate new growth, and when new growth emerges in fall, it often doesn’t have time to winterize itself to handle freezing temperatures. And, if it doesn’t put on new growth, you will be looking at a chopped up hedge all winter long. Instead, try to time your pruning to happen just before the growth surge in spring. This is a great time to shape up your hedge. Then, when it grows for spring, soft, new leaves will cover your cuts and give the plant a fresh, lovely look. If it grows too much for your space or taste, give it another trim a few months later. Just wrap up all your cutting well before Labor Day if frost and snow visit your garden.
Hedges are sheared from the outside, which removes controlling growth hormones and encourages the plant to sprout out at every cut location (and other spots too). This can also lead to the interior of the plant defoliating, so it’s important to take the time to hand clear the detritus. Left to build up, the accumulation can provide pest habitat and encourage disease. Clearing it out will help keep your hedge healthy.
Because dense, top-to-bottom foliage is the goal in growing most hedges, its important to be sure sunlight reaches all of the leaves. To do this, be sure that the bottom of your hedge is slightly wider than the top of the hedge. Otherwise, the wider top growth may shade the bottom from needed sunlight. Be mindful of this as you trim layers off the plants. Pruning this way can feel counterintuitive. Take the time to step back as you’re working and observe your progress.
Start your pruning task by shaving off relatively thin layers of plant material. In the end you don’t want to have a hedge with several bald spots in the middle. And, with many hedge, cutting deeply into wood without leaf growth will result in a hedge with permanent bald spots. Conifer hedges, in particular, have difficulty forming new growth from stems deep in the interior of the plant.
Using the right tool for the job is also important. Along with a good pair of hedge shears, keep a hand saw and pruner nearby as well. These will be helpful should you encounter any larger branches that require sawing and to wrap up any final, fine-tuning cuts.
If your hedge gets laden with snow or ice in winter, be sure to get outside and dust off the heaviest weight with a broom. Do this gently so that you do not break delicate, frozen branches at the same time. Remember: a light layer of snow will help insulate your shrubs from frigid temperatures; a heavy layer will deform your hedge and possibly break over-burdened limbs.