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Propagating shrubs from hardwood cuttings
Propagation of shrubs and trees from hardwood cuttings
is not as difficult as it appears. Hardwood cuttings are tough
and require less skill, care and attention than softwood cuttings.
Deciduous shrubs are now entering their period of dormancy making
this an ideal time to take hardwood cuttings for rooting in the
spring.
Hardwood cuttings are sections of this
year's growth that have matured. They range from an eight of
an inch in diameter to around an inch. Diameters of less than
one-half inch are recommended. The length can be between four
inches and two feet, depending upon the shrub or tree providing
the cuttings. Six to ten inches are convenient sizes to handle.
Choosing wood for cuttings
Cutting should be taken from wood that has made vigorous, but
not excessive growth during the past year. Avoid wood that shows
evidence of damage by insects or disease. Branches with closely
space nodes or buds are recommended. Shrubs can be encouraged
to produce good shoots for cuttings by cutting back the shrub
in the spring. This can be done without damaging the appearance
of the shrug by choosing less visible areas of the shrub and
limiting the area cut back. This kind of treatment is unnecessary
when only a few cuttings are desired.
A single branch or stem can be divided
into more than one cutting. I know of only two exceptions to
this statement. Hibiscus and weigelia propagate successfully
only from tip cuttings.
Taking the cuttings
It is recommended that you use a sharp knife to make cuttings.
Pruning shears tend to crush the plant fibers causing conditions
that promote the growth of fungi. The cuttings must be planted
with the correct end up next spring. Identify the ends by cutting
the top of the cutting straight across and the lower end on a
slant. Make the top cut just above a leaf node or bud.
Perhaps you are wondering why you should
take cuttings now with the intent of rooting them in the spring.
The reason has to do with the complex behavior of cells. Essentially,
the cutting cannot root until a callus has formed on its lower
end. A callus is a layer of specialized cells that form before
the cutting can produce roots. These cells form slowly during
the dormant period if conditions are right.
Care during dormancy
Hardwood cuttings should be kept at a temperature between 65
and 70 degrees Fahrenheit for four or five weeks. They should
then be held around 40 degrees until they can be planted out
in the spring. During this time the cuttings must not dry out.
There are several methods of storing the cuttings that accomplish
this. Regardless of the method you chose to store your cuttings,
begin by tying cuttings of the same variety into bundles with
all the cuttings in the same direction. Label each variety because
by spring it is easy to forget what is in the bundle.
The bundle of cuttings may be buried in
an unused corner of the garden, below the frost line to await
spring. Place sand in the bottom of the hole and use it to cover
the cuttings to insure drainage. The bundle of cuttings may be
placed in a box of damp sand or sawdust in an unheated basement
or garage. It is important that the storage place remain cool.
If it does not, callusing and rooting will occur so rapidly that
the stored energy in the cutting is exhausted before the cutting
can be set out in the spring.
Cuttings can be stored in the refrigerator
after the initial period required to develop the callus, if no
other place is available. Place the cuttings in a plastic bag
with a handful of damp sand or sawdust and put it in the vegetable
bin. Check cuttings, other than those buried in the garden, periodically
to insure they do not dry out.
In the spring
In early spring, when the soil has
become workable, the cuttings can be placed in a nursery bed
or a suitable container. The soil must be well-drained, but capable
of retaining moisture. Soilless planting mixes work well in containers.
Set the cuttings into the soil at a depth between one-half and
two-thirds of their length. It is essential that the soil is
kept moist during the cuttings first season. Cuttings potted
in containers may require light feeding after they have developed
roots and leaves.
The first winter
Rooted cuttings should remain in the nursery bed for their first
winter. A few exceptionally vigorous cuttings may be moved to
their permanent location with little risk of losing them. Cuttings
rooted in containers may be set into the nursery bed or their
permanent location. New plants that are held over the winter
in their containers must be protected from drying out and from
above ground temperatures. Bringing all the containers together
and covering them with mulch or sawdust should get them through
the winter. Mulch the new plants after the ground has frozen.
Email Frank
Sommer
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