How to Prune Thuja Pyramidalis
Thuja pyramidalis is a narrow evergreen arborvitae known for its tight upright habit. Used commonly to form a living screen, it also serves as an accent point in formal gardens. As an accent plant, thuja pyramidalis requires little or no shaping, only removal of diseased or broken branches. Planted as a hedge or screen it requires a type of light pruning known as shearing. Shearing lightly to maintain shape once the desired width and height are reached will keep screens and hedges looking their best. Does this Spark an idea?
Other People Are Reading
Things You'll Need
- Loppers
- Small pruning shears
- Pruning saw
- Hedge shears or power hedge trimmer
- Poles
- Garden twine or wire
Instructions
-
Pruning Single Thujas
-
1
Prune back dead wood in winter to encourage spring growth by using thinning cuts. Remove the whole stem or branch back to the main stem or to the point where it joins another branch.
-
2
Remove weak, broken or diseased branches by making thinning cuts. Cut back to the point where the damaged branch joins another good branch. Splitting along the entire length of a branch or close to the trunk requires removing the branch where it meets the trunk.
-
-
3
Remove branches that are dangerous or obstruct buildings or power lines by using thinning cuts.
-
4
Clean loppers, pruning shears or pruning saws between each cut by wiping away plant matter. Disinfect between cuts by dipping in a 10 percent bleach solution.
Prune Hedges by Shearing for Height
-
5
Shear thuja hedges in early spring through mid-summer to slow the growth rate and retain hedge form. Begin shearing in the second year after planting, according to the Corona professional pruning manual. Do not shear in late summer or fall.
-
6
Shear a thuja hedge to the desired height by making and setting a guide. Make the guide from two poles taller than the hedge height and garden twine or wire.
-
7
Put poles at the midpoint of the thuja hedge at either end, level them and stretch string or wire along the length of the hedge at the desired cutting height. Shear back to that height every spring.
Prune by Shearing Hedge Taper
-
8
Shear thuja hedge sides tapering inward toward the top. Requiring only a slight taper ,the top of the thuja hedge will be only two feet narrower than the base. Make a guide to set the batter (hedge taper) using a pole with a crossbar mounted at the same height as the hedge top.
-
9
Measure one foot out along the crossbar and mark it, then drive a nail ¾ of the way in at that point. Attach enough string to reach to the ground from the crossbar, tying it in front of the nail so it can't slip back past the one foot mark.
-
10
Put a nail in the upright at the same height as the thuja hedge base. Pull your string taut and tie it to the upright below the nail. Tying under the nail keeps the string from slipping up and ruining the hedge taper.
-
11
Set the pole in front of the hedge with the crossbar extended toward the hedge. Make sure the pole is level and that the bottom of the crossbar is even with the top of the hedge. The base of the string should be right at the outside of the thuja hedge base. The upper part of the string may be inside the hedge if no taper has been sheared before.
-
12
Shear using the string as an angle guide and be careful not to cut the string. Move the pole along the hedge, shearing as you go, till you reach the end of the hedge. Repeat on the other side of the hedge. Use the guide in subsequent years to maintain the taper.
-
1
Tips & Warnings
According to the Corona professional pruning manual gardeners should "begin shearing a new hedge in its second or third year. Shear it regularly thereafter. Do not allow a hedge to reach its desired height and then begin shearing it for a compact, dense habit. Develop a small, dense hedge first then let it slowly reach the desired height."
A more permanent batter guide can be made using 16 gauge plastic coated wire in place of string.
Cutting back into old brown wood creates bald spots since thuja pyramidalis grows only from green shoots.
Shearing in late fall or early winter will cause tip burning.
According to Ohio State University Horticulture department in their 2009 bulletin, "Thuja occidentalis," thuja pyramidalis is subject to winter burn and yellowing.
