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The Complete Guide to Landscape Design, Renovation,
and Maintenance
by Cass Turnbull
TIMING
New gardeners are often overwhelmed by the deluge of conflicting
advice they get as to the right time to prune. Some experts say
to prune "when the shears are sharp," while others, warning
about the way trees bleed in the spring, urge "dormant pruning."
I'd like to introduce the general rules of good timing and mention
some specifics, too. A little known or appreciated fact is that
pruning stimulates growth.
Spring
In the early springtime your plants are most vigorous and pruning
will stimulate new growth the fastest; it's also the best time for
a plant to recover from severe pruning. Try to wait until danger
of frost is gone, because if your pruning stimulates lots of new
soft growth, this growth might freeze off. It will not freeze the
old "hardened off" wood, though. Spring is a good time
to renovate your giant aucuba ball, when you will be cutting into
all that black looking inside growth, and this will give it maximum
time to green up again. When you radically reduce the size of a
hedge, you expose ugly dead looking branches. If you must do this,
know that early spring is when the new growth will come back fastest.
Spring is a good time to prune anything that you are worried about
killing with heavy pruning. Rhododendrons are touchy, and sometimes
when you prune back to an old node (branch or bud), the whole branch
simply dies. Early spring is when they are most vigorous and you
can spot swelling hidden buds along the stems, to cut back to. You
will have a better change of stimulating growth.
Spring is the time for bud work. You can rub off new buds growing
from places where you've thinned off branches before--this may stop
them from becoming suckers (or watersprouts). In my area, where
the climate is mild, early spring (Washington's Birthday) is when
we heavily prune back hybrid tea type roses. It is easy to spot
the swelling buds to cut back to. Later in the spring is the time
to prune the elongating buds called candles from the tips of pines.
The Japanese either twist or cut them off, or even cut them in half.
This prevents pines from getting bigger and gives them the puff
of clouds look. It's how you stop your pine from becoming enormous.
It's almost impossible to make pines smaller again without ruining
their natural form. It is far better to thin or layer your pines
as they grow than to wait until you think they are suddenly too
big and then try to make them smaller.
Contrary to common practice, spring is not a good time to prune
fruit trees or flowering ornamentals (flowering and fruiting cherries,
plums, crabapples). This is because these plants are prone to suckering
back. Suckers, you recall, are the weak, wild, skinny, upright branches
that often result from wounding or pruning. The more heavily you
prune, the more suckers you get. So always go lightly in pruning
these trees, say one-eighth of total green area in any one year.
Avoid heading cuts on the ornamentals (means not fruit trees).
Other readily suckering plants are magnolias, dogwood, witch hazel,
figs, parrotia and hazel nut (filbert). You should prune these generally
in the summer to reduce sucker regrowth. There is another group
of trees (maple, dogwood, pine, birch) called "bleeders,"
that lose sap at a frightening rate if you prune in the spring.
I am told that this loss of sap does not actually endanger the plant's
health, but it looks messy. Prune these trees in the summer or winter.
Grapes bleed as well.
Avoid pruning all trees during the weeks in spring that they are
forming leaves, and during the time the leaves are falling in the
autumn. These are times of low energy for your trees and the added
stress of pruning is not wise.
Summer
Summer pruning is less stimulating to plant growth. It is, however,
somewhat more stressful to the plant, so be sure your plants are
well watered and healthy and don't pick on rhododendrons or other
touchy shrubs. Summertime is great for spotting dead wood, as you
know. Because of the nonstimulating effect of summer pruning, it
is a good time to tidy up that laurel hedge or those abelias, because
they won't grow back right away. Summer pruning in the Pacific Northwest
means June and July. In hotter climates, ease off even earlier.
Summer is a good time to snap out new sucker growth, or cut it off.
Battling suckers is much of what I do as a pruner. Avoid heavy pruning
(except for suckers) during droughts. Drought is stressful on plants;
so is heavy pruning. Also, it will take a long time for your plant
to regrow. You may burn some previously shaded leaves or the bark
inside your plant or tree.
Fall
Fall pruning is risky only with certain plants. Some plants are
considered tender, which means their tips freeze back easily, and
sometimes whole branches do. (In my climate zone, roses, choisya,
laurestinus, Viburnum tinus, raphiolepis, and laurels are tender.)
I have noticed that many of these are the plants that take full
sun. It makes sense that these plants, perhaps from warmer climes,
are not used to colder weather. Also, in the fall, when the days
are somewhat warm and wet, plants are occasionally tricked into
thinking spring is back, so you may not wish to chance stimulating
more soft tender growth. Some people feel that fall pruning is rather
stressful on plants, but a little thinning and touching up is always
in order in any season. You can, of course, always take out the
dead wood.
Winter
Winter is a favorite time for professional gardeners to prune, especially
trees. That's because we are usually too busy weeding and doing
absolutely essential pruning in the spring and summer. In winter
we have the time to get out our ladders and dive in among the branches
and really sort the garden out. Winter pruning also stimulates growth
(next spring), but less so than spring pruning. When all the leaves
are gone, it's easier to see the branch pattern on some of the big
deciduous shrubs, such as forsythias and European cranberries (Viburnum
opulus).
Bloom Time
Another consideration for deciding when to prune is flower production.
You will read that some plants bloom on year-old wood, or two-year-old
wood, or on buds set up this season, or that are maximum on three-year-old
wood. This is all very confusing. A good rule of thumb is to prune
right after blooming so that the plant has time to set up buds for
the next year. But it's just a consideration for gardeners who are
really into their flowers. You know it does not hurt the shrub to
prune it at the wrong time. You don't shock buds into not forming,
you just cut off some. In fact, some gardeners prune before blooming
so that they can bring in the barren-looking twigs of, say, forsythia,
quince, sweet smelling witch hazel, put them into vases of water,
and force them to bloom early in their warm homes. Such are the
rewards for clever gardeners. If you are selectively pruning and
thinning your shrub or tree, this should not make a big difference
to the casual observer come bloom time. It makes a big difference
only if you shear or otherwise head back all the branches of your
shrub after it has made its flower buds; then you will be cutting
off all the buds. But you shouldn't be shearing your flowering shrubs,
anyway. I pay closer attention to bloom time when pruning plants
that have one big show and then quit, as opposed to ones that push
out flowers on and off throughout the season.
Now you have the facts before you, and you may decide for yourself
when to prune. There are many oddities to know about plants that
you can look up in your local pruning encyclopedia. You will, however,
have to know the names of your shrubs first. I suggest you make
a little map and get the lady with the yard down the block to come
help you identify them; she will be flattered. Or you may want to
hire a professional gardener; he or she can get you off to a good
start, too. In any case, don't be intimidated by the notion of right
time pruning. If you are out renovating your yard, it's then that
you "prune when the shears are sharp."
SUMMARY
People make too big a deal out of proper timing. General thinning
is okay almost any time of year.
Following are general results of pruning at different seasons of
the year.
1. Spring - Produces rapid regrowth. A good time for any bud work.
Watch out for "bleeders" (maple, dogwood, walnut, grape,
birch).
2. Summer - Summer has a somewhat dwarfing effect, but is harder
on health of plant; a good time to battle suckers; a good to spot
dead wood on deciduous plants.
3. Fall - May be stressful on plants. May stimulate tender growth
that will freeze when winter comes. General light thinning is always
in order.
4. Winter - Good to prune deciduous plants. Traditional time for
fruit trees. Good for heavy work. Will also stimulate growth next
spring.
Forward to Pruning Cane-Growers
Back to Looking for Dead Wood
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