Pruning Landscape Plants
"To prune or not to prune - that is the
question!" It is a question which many anxious people
consider each year at this time.
Proper pruning enhances the beauty of almost
any landscape tree and shrub, while improper pruning can ruin
or greatly reduce its landscape potential. In most cases,
where landscape plants are concerned, it is better not to
prune than to do it incorrectly. In nature, plants go years
with little or no pruning, but man can ruin what nature has
created. By using improper pruning methods healthy plants
are often weakened or deformed.
In nature, every plant eventually is pruned
in some manner. It may be a simple matter of low branches
shaded by higher ones, resulting in the formation of a collar
around the base of the branch, restricting the flow of moisture
and nutrients. Eventually the leaves wither and die, and the
branch will drop off during a high wind or storm. Often, tender
new branches of small plants are broken or pulled off by wild
animals in their quest for food. In the long run, a naturally
growing plant assumes the shape that allows it to make the
best use of light in a given location and climate. All you
need to do to appreciate a plant's ability to adapt itself
to a location is to walk into a wilderness and see the beauty
of naturally growing plants.
More trees are killed or ruined each year from
improper pruning than by pests. Remember that pruning is the
removal or reduction of certain unnecessary plant parts—parts
that are no longer effective or that are of no use to the
plant. Pruning supplies additional energy for the development
of flowers, fruits and limbs that remain on the plant. Pruning,
which has several definitions, essentially involves removing
plant parts to improve the health, landscape effect or value
of the plant. Once the objectives are determined and a few
basic principles are understood, pruning is primarily a matter
of common sense.
The necessity for pruning can be reduced or
eliminated by selecting the proper plant for the location
at the outset. Plants that might grow too large for the site,
are not entirely hardy, or become unsightly with age should
be used wisely and kept to a minimum in the landscape plan.
Advances in plant breeding and selection in the nursery industry
provide a wide assortment of plants requiring little or no
pruning. However, even the most suitable landscape plants
often require some pruning.
Pruning should follow a definite plan. Consider
the reason or purpose before cutting begins. By making the
pruning cuts in a certain order, the total number of cuts
is reduced greatly. The skilled pruner first removes all dead,
broken, diseased or problem limbs by cutting them at the point
of origin or back to a strong lateral branch or shoot. Often,
removing this material opens the canopy sufficiently so that
no further pruning is necessary.
The next step in pruning is to make any training
cuts needed. By cutting back to lateral branches, the tree
or shrub is trained to develop a desired shape, to fill in
an open area caused by storm or wind damage, or to keep it
in bounds to fit a given area. To properly train a plant,
you should understand its natural growth habit. Always avoid
destroying the natural shape or growth habit when pruning.
Make additional corrective pruning to eliminate
weak or narrow crotches and remove the less desirable leader
where double leaders occur. After these cuts have been made,
stand back and take a look at your work. Are there any other
corrective pruning cuts necessary? If a considerable amount
of wood has been removed, further pruning may need to be delayed
for a year or so.
To open up a woody plant, prune out some of
the center growth and cut back terminals to the buds that
point outward. In shortening a branch or twig, cut it back
to a side branch and make the cut 1/2 inch above the bud.
If the cut is too close to the bud, the bud usually dies.
If the cut is too far from the bud, the wood above the bud
usually dies, causing dead tips on the end of the branches.
When the pruning cut is made, the bud or buds nearest to the
cut are usually the new growing point. When a terminal is
removed, the nearest side buds grow much more than they normally
would, since apical dominance has been removed. The bud nearest
the pruning cut becomes the new terminal. If more side branches
are desired, remove the tips.
The strength and vigor of the new shoot is often
directly proportional to the amount that the stem is pruned
back since the roots are not reduced. For example, if the
deciduous shrub is pruned to 1 foot from the ground, the new
growth will be vigorous with few if any flowers the first
year. However, if only the tips of the old growth are removed,
most of the previous branches are still there and new growth
is shorter and weaker. Flowers are more plentiful although
smaller. Therefore, if a larger number of small flowers and
fruits are desired, prune lightly. If fewer but higher quality
blooms or fruits are wanted in succeeding years, prune extensively.
The height of a tree or shrub with 2 or more
stems of equal size and vigor competing for dominance can
be controlled by the length which they are cut back. A tree
or shrub with 2 branches growing at the same height is commonly
known as a split crotch, double leader or weak crotch. For
a stronger plant that can better withstand ice and wind, cut
1 branch back or remove it completely. The remaining branch
assumes apical dominance over other cutoff branches.
Thinning is a method of pruning usually recommended
for most landscape trees. When thinning, remove an unwanted
branch at its point of origin or at a strong lateral branch.
This method conforms to the tree's natural branching habit
and the results are less conspicuous. Thinning makes a more
open tree and emphasizes the internal structure of the branches.
Thinning also reduces breakage in wind and ice storms. Live
oaks, in particular, need to be thinned out for this reason.
Unfortunately, dehorning, topping or heading
is used too often to reduce tree size. While more rapid than
thinning, the results usually are much less desirable. Re-growth
is vigorous and upright from the stub. New branches form a
broom?like growth arising from adventitious buds just below
the surface and usually are weakly attached to the bark of
the stubbed?back branch. Actually, it is a bunch of water
sprouts weakly attached to the main trunk. Therefore, during
wind or ice storms the branches break off easily.
Topping also shortens the life of trees, rendering
them susceptible to insect and disease attacks. It also destroys
the tree's natural shape. Do not prune the central leader
of trees unless necessary. Over a period of several years,
remove or cut back branches that compete with the leader if
the branches are large. The crook that results at the base
of a new leader seldom is noticeable after a few years.
For more information on pruning of ornamental trees and shrubs,