The Complete Guide to Landscape Design, Renovation, and Maintenance
by Cass Turnbull

THE SCIENCE OF PRUNING
There are only two kinds of cuts in pruning. One is the heading cut, which means the cutting off of the tips of branches either bluntly (called stubbing), i.e., not to another side branch, or selectively, back to a smaller side branch or to a bud.

Examples of heading cuts are topping, tipping back and pinching.

Severe heading of trees is called topping. Don't do it. An alternative called drop crotching is used by responsible tree pruners when they are forced to try to reduce the actual height (not mass) of a tree. It consists of heading a branch or leader back to another smaller (but not too small) branch. Other kinds of heading are tipping back, and very light heading, by just nipping off the tips of new shoots with your fingertips, which is called pinching. Shearing consists of many no selective heading cuts. Heading is good to do to your formal hedge or to your young chrysanthemum to make it bushy. In fact, all heading cuts stimulate bushiness at the tips of branches. I call this the hydra effect. Wherever you make a nonselective heading cut you will stimulate many hidden buds to pop or break, meaning they will grow out near the tip of your cut branch. The nonselective heading cut gets people into trouble. They go out and whack back the tips of all their shrubs and trees in an effort to control size and they stimulate a lot of thick rapid regrowth.

Thinning cuts take branches off where they began as buds.

Thinning
The other type of cut and the one we use most in selective pruning, is the thinning cut. You cut branches or twigs back to other branches or twigs or cut out whole canes clear to the ground. Technically speaking, thinning removes a twig or branch back to where it began as a bud. But selective heading, that is, taking a big branch back to a smaller side branch will thin a shrub out, too. The rule of thumb is to cut to a side branch no smaller than one-half the diameter of the wood you are cutting. It will not stimulate bushy regrowth when used appropriately. This applies to shrubs. Trees, with the possible exception of fruit trees, don't take well to heading, even selective heading.

You can't simply cut back a tree branch to one-half its length and expect it to live. There will not be enough leaf area to gather food to support the mass of the remaining stem. It will either resprout vigorously or die. Besides, it looks bad. So, it is better to remove the branch totally, taking it off back where it joins a larger stem, if you can, rather than head it severely. Heading is harder on a plant in proportion to the size of the cut and the greater age and bulk of the plant--for example, an old big tree. Plants also vary as to how much cutting they can take according to their species. Laurel can take it, but a sugar maple may die.

Selective heading removes a branch where it joins a side branch of sufficient size. This reduces height while retaining some of the natural shape of the shrub.

Non-selective heading will cause die-back of the branch or it willstimulate rapid, bushy regrowth.

Cut to the node!

Most people want to prune to reduce the size of their plants, and, in fact, many can be reduced dramatically in size, always thinning as you do so. But let me add that most of what I do as a professional is to prune out internal branches so that you can see into or through the plant. I also thin to break up the exterior solid ball appearance of both old and young plants. This gives your shrub more character and definition. In addition, I prune to create definition between shrubs so that instead of a mass of giant greenery jammed against the house, you can see three shrubs of different types, with room between them and the house. You will be able in some cases to see the dirt beneath them.

Types of nodes.

It is not immediately apparent how following the rules by cutting dead, crossing, and crowded branches will result in a nicer, smaller looking shrub. So beginning gardeners will just have to follow the recipe with faith until they see the connection. In the beginning, don't agonize over which one is the right branch, just take your best shot and see how it goes. Stand back and observe the effect on the overall appearance.

When you make your cut, do so just above a side branch or bud, slanting the way the bud is facing. Don't cut too close, but don't cut too far away.

Plant Terminology
This brings me to a little plant terminology. A shorthand way of saying, "a bud or side branch" is to say, node. This is your first lesson in how to speak gardenese. Knowing to cut to the node separates the pros from the amateurs in gardening. A node can also be a place where a leaf or branch used to be and where a dormant bud remains. Such a node will look like a bulge in the stem with a line or leaf scar where the leaf once was. If you cut to the node, a dormant bud will begin to grow out and form a new branch. And, if you say "soil" instead of "dirt" and "shrubs" instead of "bushes" you are well on your way to speaking gardenese.

Branching patterns.

Plants are categorized by their branching pattern into alternate, opposite, and whorled. The vast majority of plants are alternate in branching. Opposite plants are harder to prune, because it's hard to squeeze the tips of your hand pruners into the "V" to cut so as not to leave a stub to die back. Stubs are the dead section of branch that occurred when the last person didn't cut to the node and so the branch died back. If buds or twigs are opposite each other--just cut off straight and as close as you can.

There's another reason why it's harder to direct the growth of opposite plants: often the branch you chose because it was headed in the right direction (out from the center) is accompanied by one going the opposite (wrong) way. Do the best you can. One solution is to cut off the inside branch as well.

How to make a stub.

A little more terminology, now. Suckers! Technical types like to point out that suckers are the straight up shoot growth that comes from the base or roots of the plants, and watersprouts are the skinny, ugly, straight up growth that occurs on branches. Common usage has it, however, that all young straight up new shoots are called suckers. I like the way it sounds, too. I like the verb suckersback to describe what happens when the hapless homeowner hammers his hawthorn in a misguided attempt to keep it small. Next to dead wood (including stubs) we want to reduce or eliminate watersprouts or suckers on plants. Straight up is generally less pretty than curving. For more information on suckers you will need to read the chapters on 'Fruit Trees' and 'Rehabilitating Shrubs.'

Pruning "opposite" plants is difficult.

I often tell people that pruning is a skill like any other. You must pay attention and then practice. Learning to do a decent job of pruning takes more time and effort than learning to vacuum, but less than learning to play basketball. The sport of pruning takes about as much time and attention as learning to play a decent game of ping pong. In this chapter we have gone over some rules of the game. Now you must go out and practice, practice, practice.

SUMMARY
1. Pruning--especially heading--stimulates growth.
2. Use thinning cuts. Avoid cutting ends or tips of branches to make things smaller. It often backfires.

Heading Cuts
- Nonselective heading is good to stimulate bushiness. Examples: sheared hedges, chrysanthemums.
- Selective heading is the cutting back to a side branch or bud. The remaining branch should be at least half the size of the one being removed. This reduces the plant size and is less likely to stimulate sucker resprouting or create dead stubs.

Thinning cuts
Thinning cuts remove branches to the point where they began as buds, or remove total canes to the ground. They are better for the health and good looks of plants, especially trees, than heading cuts. Thinning reduces bulk and sometimes height of shrubs (when canes are removed). Shrubs and trees vary in degree of thinning they can withstand. A pine tree will take a lot of thinning; a cherry tree resents even moderate thinning.

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