January
2005
By
B. Rosie Lerner
Extension Consumer Horticulturist
Purdue University
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Late Winter Recommended for Pruning Chores
If you're itching to get outdoors and work on your garden, now's a good
time to survey your landscape and decide what needs pruning. But keep
in mind that not all plants need to be trimmed.
Landscape plants should be pruned to maintain or reduce their size, to
remove undesirable growth, to remove dead or damaged branches, and to
rejuvenate older plants to produce more vigorous foliage, flowers and
fruits. In some cases, pruning is necessary to prevent damage to life
and property.
Pruning isn't as difficult as most people think, but there are proper
techniques to keep in mind. Late winter or early spring, before new growth
begins, is generally considered the optimum time to prune most plants.
This is when the plant's wounds heal quickly, without threat of insect
or disease infection. However, plants that bloom in early spring, such
as forsythia, magnolia and crabapples, should be pruned later in spring
after their blooms fade. These early bloomers produce their flower buds
on last year's wood, so pruning early will remove many potential blooms.
Trees that have large quantities of sap in the spring, such as maple,
birch and dogwood, are not harmed by early spring pruning but can be pruned
in mid-summer or late fall to avoid the sap bleeding.
It's best to allow a tree or shrub to develop its natural shape as much
as possible. However, removing selected branches because they are weak
or formed at a poor angle to the trunk will help the rest of plant receive
more sunlight. Thin this type of growth by removing unwanted branches
at their point of origin. Make the cut just beyond the branch collar,
which is the ridge of bark that surrounds the junction of that branch
to its point of origin. This will leave a very short stub of about one-half
to 2 inches, depending on the size and age of the branch.
If reduction in size is desired, a technique called "heading back"
is recommended. Shorten branches by cutting back to a healthy side bud
or branch that is pointing in the direction you want future growth to
occur. Make a cut about one-fourth inch above the bud or branch.
Evergreen trees, such as firs, pines and spruce, are not pruned by the
same methods as other plants. They can be encouraged to produce stockier
trees by pinching the "candles" of new growth, which emerge
in late spring. Pinch out one-half of the candle when it reaches approximately
2 inches long. Use a sharp knife or your fingers to pinch, instead of
a shears, which can damage the needles surrounding the candle.
Shrubs that have become overgrown, or perhaps don't flower like they used
to, might benefit from renewal pruning. Each winter for the next three
years, you remove about one-third of the oldest, largest-diameter stems,
all the way back to the ground. The other two-thirds can be headed back
about one-third of their height by cutting back to an outward-facing bud
or side branch. After the third year, all of the plant's stems will be
no older than 3 years.
Whatever the tree or shrub, remember that topping or haircut trimming
are not sound pruning practices. Topping results in numerous, fast-growing
new shoots, which are much weaker and more susceptible to wood rots than
the original growth, and are more likely to cause damage to property and
power lines. Use the heading-back technique to reduce the plant's height.
This technique may be more costly in time or money, but the results are
worth the extra effort.
Also, keep in mind that for larger trees and shrubs, which are beyond
the ability of the average homeowner's hand tools, you may need to call
in a professional. Be sure to ask for estimates and references from satisfied
customers.
For more information about pruning, you can download a copy of Purdue
Extension Publication HO-4, "Pruning Ornamental Trees and Shrubs"
at http://www.hort.purdue.edu/ext/HO-4.pdf or contact the Purdue Extension
office in your county.
1-20-05
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