Keeping shrubs small

Simple steps for restriction pruning,
making an example of a yew hedge.

We hope this helps you!

Keeping a plant smaller than its potential has the simplest of all steps:

1) Assess the new or existing plant.                          2) Establish a limit for height and width you can allow.




3) Allow the plant to grow. After one year this one didn't reach its limit. So the gardener did not prune.

restrct3of7.jpg  restrct4of7.jpg

 4. In the year when the plant grows beyond the line...


...cut off everything that crosses the line.

5) Thin the surface. Clip farther back about 20% of the branches to allow them to grow for at least a year before once more reaching the line.

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Step 5 thinning allows light to reach the plant's interior. Fresh new growth will always be coming from within. Outermost branches will not become dense witches' brooms that block light and bear too little foliage to support vigorous growth and good health.

More photos of steps 4 and 5 in Cut n expectations.

An overgrown yew hedge at the foundation:

Sometimes we must first reduce a plant that's gotten away from us. Watch us reduce this yew hedge and then apply simple restriction pruning.

Our target: Four yews that make up the central low hedge along this north-facing foundation.

Their history: Sheared annually without any thinning for over ten years. Each spring they lost most but not all of the new soft growth. So every year they gained a little in height and width until they filled the bed from walk to wall and each year threatened to block the windows.  



The plants' history, continued: They became woodier every year.iHdgBegnDens0456s.jpg

Stubs branch after shearing. The tips branch and branch again. These yews' surfaces became increasingly criss-crossed and tangled (right) and this shell blocked light that once reached the interior. Foliage in the plants' centers died and new buds ceased to develop. The surface and sides became less leafy, too, since needles grew only on the upper side of the shell of tangled twigs.

So, the plants became weaker. Leafy cells create fuel from sunlight -- a feat wood and roots cannot match. With far more wood than leaf and every woody cell relying for energy on the leaves' photosynthesis, the plants have less energy to use for repairing damage, surviving tough times, and creating substances that discourage pests.

Our two objectives: To make the shrubs healthier as well as smaller. We want to lower them and also reclaim room for some annual flowers and the contrasting border of hostas.

Below: A border of hostas? Where?! In that narrow space at Janet's feet, hostas grow. They lap onto the walk like ketchup squeezed from an overstuffed sandwich bun.
Janet's checking the depth of foliage to answer the question, "How far can we cut these before we're going to see nothing but bare wood?



Our two options:

A) Start from scratch:
• Cut the shrubs all the way to needleless stubs just a few inches tall,
• Wait for the bare wood to "break" -- sprout new greenery --
• Then begin pruning when they return to the desired height and width.
That process would take about two years, given a healthy yew's 12-inch growth rate.

B) Reduce and gradually rejuvenate.
• Cut the shrubs back to a few inches below the desired height and width, and
• Thin them so light reaches the inner wood.
Afterward, some breaks should occur in the depths and on the bared sides, and more will come as we thin the plants' shells each time we prune. That will give depth to the foliage layer for better health and a richer appearance.

We chose option two.

Below: Our first cut lowered the top. It completely bared the front as we cut it back away from the walkway and sloped that side to prevent upper branch tips from shading those below. We cut hard, to leave thick stubs that could yield the heftiest new shoots.
We made this cut in early spring before budbreak, timing that usually insures development of breaks.



Setback! Unfortunately, the shrubs  didn't break in response to the first cut.

That's okay. Sometimes breaks don't occur right away. They might be delayed by a plant's diminished health -- years of living with almost more wood than the meager foliage could support. Another damper can come from weather -- a hot, dry spell can suppress production of new shoots.

Whatever the reason, these shrubs did not break in their first season. They will.

Below: At the end of the season we cut bare wood further, since thick stem bases tend to yield stronger shoots.

CYewHdgNov11N2938s.jpg DYewHedgeCut2N2952s.jpg


Then, we waited. At least they're more thickly leafed after a summer's growing than they were when we first cut (far right).

EYewHdgNovHtN2949s.jpg YewHdg11Apr1874s.jpg


We begin restriction pruning:

Year two began, and still no breaks deep inside. A very odd growing season might be to blame -- it came early, then froze new shoots before turning very dry and hot.

Whatever the reason for the stall, we know they will break in time. For now, we give the shrubs a pep talk and commence standard reduction pruning and thinning.

Below:  Here is the hedge shorn almost all the way across its top (below, left)  and all clipped (below, right).

FYewHdgJul12N7042s.jpg GYewHdgCutJu12N7044s.jpg

Below: Left side cluster is about to be thinned; right side already thinned. The hedge's surface is still dense, even after two rounds of thinning cuts. But there is more light reaching the middle than before and that will be the key to eventual breaks.


As these yews grow this year and next we'll post updates.

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