of Rhode Island GreenShare Factsheets
There are two types of hedges, formal and informal. The
formal hedge is pruned or sheared to a definite size and shape
one or more times each growing season. The informal hedge, often
a row of shrubs planted close together but allowed to grow normally,
is pruned annually to thin out the oldest wood and to maintain
a desired height and width.
After planting, small shrubs one to two years old should
be cut back to about 6 to 10 inches above the ground. This will
force new shoots near the ground to develop into a thick, bushy
shrub. Delay in cutting back at planting, a fault of many gardeners,
will result in a leggy, unsatisfactory hedge later.
Older shrubs used to start a hedge can be cut about one-third
from the top. This helps develop a thick, bushy hedge of many
twiggy stems. No additional pruning is needed on newly-planted
hedges until the next spring.
The most important step in starting
a new hedge is the first shaping the next season after planting.
A narrow pyramid
or inverted "V" is the recommended shape. For example, a hedge
5 feet high should be 2 1/2 feet at the base and about 1 foot
at the top to be in good proportion.
The top of the hedge should be trimmed slightly rounded
or pointed. This allows sunlight to reach the lower branches.
If the top becomes as wide or wider than the base, the lower
portion is too shaded and produces thin weak growth. A taller
hedge requires more attention to maintain proper shape and taper.
Hedges can be kept vigorous for years by annually thinning
out a third to a fourth of the oldest branches with hand pruners
or pruning saws. In addition to regular shearing, cut these branches
back to the parent stem at the ground or to a lateral, or side,
branch in the spring before growth starts.
Shrubs with red or bright-colored winter bark can be kept
colorful by cutting out one-third of the oldest stems each year
or prune one-third of the oldest stems every three years.
Shrubs used for hedges, except evergreens, can be pruned
almost anytime. Slow-growing hedges that require one annual pruning
can be sheared after they have completed their season's growth
in early to mid-June. Fast-growing hedges can be trimmed two
or more times, in early June, mid- to late-July and early to
Overgrown, neglected deciduous hedges can be restored to
their former beauty by one or a combination of methods. Over
a three-year period, before new growth starts in the spring,
cut back all branches to a few inches above the ground, along
with regular shearing. Another way is to cut back the top and
sides of the hedge 8 or more inches inside of the desired height
and width in early spring. Follow by shearing the new growth
for a thick, twiggy effect.
No pruning is needed after planting young evergreens three
to five years old. For the first two years after planting, prune
back only the terminals and laterals as needed to begin the desired
shape and taper.
Pine and spruce should not be pruned beyond the current
season's growth. These evergreens do not produce new buds or
growth from older branches, but from buds already formed. Prune
these conifers to remove only a part of the new growth.
Pine hedges can be trimmed with hand pruners or a knife
for best effect. Hedge shears will result in mutilated needles
with brown buds and give the hedge an unsightly appearance. One-half
to two-thirds of the early spring candle-like new growth can
be pinched by hand or cut off before the needles unfold. More
pruning can be done again in late June or early July before the
new growth hardens.
Spruce produce new growth only once a year from existing
buds. Spruce hedges can be sheared in early spring before this
new growth develops from the existing buds. The new shoots can
be sheared again in late spring to early summer, if desired.
Other evergreens such as taxus (yew), juniper, arborvitae
and hemlock make good hedges. They seldom require more than one
pruning in early spring and again in mid-July, if desired.
Hedge shears are best used to prune formal hedges. Pruning
shears are used for branches 1/2 to 3/4 inches in diameter. Lopping
shears have long handles, cutting larger branches 3/4 to 2 inches
in diameter. Pruning saws have narrow blades and coarse teeth
and are designed to cut on the pull stroke. Small curved pruning
saws are useful to prune larger shrubs.
Adapted from Fred K. Buscher,
Ohio State University Extension, 2000
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information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program