Proper Plucking - No, not Chickens - Boxwoods
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Plucking, the
selected removal of small stems from boxwoods to facilitate air circulation, light
penetration and inner growth of leaves, is an integral part of any preventative
maintenance program for boxwoods. In addition to fostering the health of the parent plant,
plucking provides a source of cuttings for propagation. This paper will focus on the
process and benefits of plucking.
In a preventative maintenance program for boxwoods, the plucking or thinning referred to
above is a high priority. When carried out on a regular basis, this process promotes the
health of a plant by allowing the sun to penetrate and air to circulate within the body of
the plant. Plucking is accomplished by reaching into the plant and breaking out stems from
two to eight inches in length over the entire area of the plant. Obviously the size of the
stems which are broken depends on the size of the plant. In plucking smaller plants up to
fifteen inches, smaller stems two to four inches should be chosen for breaking. When the
plants are fifteen to 24" then larger stems four to six inches can be broken, and
with plants above 24", the stems can be four to eight inches without hurting the
appearance of the plants. The process is similar to a barber or stylist thinning hair. The
goal is to lighten and thin the plant creating small openings for sun and air to filter
in.
Boxwoods which are grown in the direct sun have a greater need for thinning than those
grown in partial shade. The sun grown plants tend to develop very dense, thick foliage
which prevents the light and air from entering the plant. Often when opening and observing
these plants, one finds piles of deal leaves caught in the middle of the plant and aerial
roots which have developed because of the moisture held by the dead leaves. Circulating
air dries out the interior of the plant and eliminates dampness. This dryness prevents the
growth of any aerial roots. The interior of plants should be hosed out with a strong
stream of water periodically in order to clean out any accumulation of dead leaves and
other debris. The cleanliness of the interior of plants is critical in the prevention of
diseases which thrives in dampness.
Another characteristic of plants grown in direct sun without any thinning is that the
green leaves are only a couple inches deep on the plant. Because light can not penetrate
the plant, the leaves can only grow on the outside. Plucking allows light to penetrate and
leaves then develop deeper within the plant. A depth of six to eight inches is not at all
uncommon for a healthy plant and may even extend twelve itches deep on a boxwood which is
30" in height and diameter.
Plucking can be done at any time of the year without hurting the plant. However, as noted
above, late winter/early spring has some advantages. If plucking is accidentally too heavy
in places, the growth of spring will quickly cover up most mistakes. it is very difficult
to describe how much to thin a plant. One should thin evenly over the entire surface of
the plant and continue to thin until the exterior texture of the plant is very loose. This
looseness provides pathways for the light and air.
The shape of a plant can be modified over time through regular plucking. Often a boxwood
may be growing over a walk or through a railing. In these instances, one can pluck very
heavy in the area that needs to be taken back. This does not mean that you take it
completely back in one plucking leaving a bare sided plant. One can pluck a plant two or
three times a year while still leaving the boxwood looking fairly normal. The principal is
the same-as in one's checking account. if the rate of plucking is heavier than the rate of
growth, the plant will diminish in size over time. A large scale massacre of a plant is
not necessary and in addition, harmful to the plant. Simply consistent plucking in
strategic locations will change a plant to your desired size and shape with time.
Hopefully, by this time it is obvious that one never "shears" boxwoods with a
hedge trimmer. It is often said that one-should never say "never". However, I
believe that with respect to this topic I can say "never use shears". Shearing
violates all the principles which plucking attempts to accomplish. Only the outer, layer
of leaves is removed in shearing. The plant then is just as dense as it was before
shearing. In addition, the shearing will contribute to new growth only on the outside of
the plant which results in the plant having a greater outside density than prior to
shearing. This greater density obviously inhibits light penetration and air circulation.
Also, contrary to plucking which facilitates the inner growth of leaves, shearing only
promotes outer growth. Shearing also destroys the natural appearance of boxwoods. It
creates a very smooth, manicured look which is very different than the traditional
cloud-like textured appearance of a boxwood.
One last benefit of plucking is that if done at the right time of year you will be able to use your clippings to propagate new plants. See the paper on PROPAGATION for details.
Stephen D. Southall
English Boxwoods of Virginia