Propagation by
semi-hardwood cuttings
Now that we are moving into early summer, I am think-
ing about making some semi-hardwood cuttings of
some shrubs that I want to propagate. Heloise Pressey
has an unidentified azalea with unusual deeply incised
and bright red petals that I’m planning to try. I am
buoyed in my hopes by actually rooting some cuttings
of flowering Hydrangea macrophylla last December. (I
had won one of the ikebana arrangements done at our
Christmas party.)
 
There are four main types of stem cuttings: herbaceous,
softwood, semi-hardwood and hardwood.
 
Herbaceous are probably the fastest and easiest to
root. Many annuals fall into this category, e.g. coleus,
many salvias, sweet potato and sedum.
 
Softwood is prepared from soft, succulent, new
growth of woody plants (May to July). Examples
include arborvitae, fir and viburnum.
 
Semi-hardwood cuttings, prepared from partially
mature wood of the current season’s growth, can be
taken from many broadleaf evergreen shrubs, e.g. abelia,
azalea, boxwood, camellia, daphne, holly, jasmine.
 
Hardwood cuttings from dormant, mature stems in
late fall to early spring, can be taken from many of the
same plants listed for semi-hardwoods.
 
The Procedure:
 
Semi-hardwood cuttings are taken normally from mid-
July to September. The wood is reasonably firm and the
leaves of mature size. A higher percentage of rooting is
obtained from cuttings taken from higher parts of the
plant, lateral rather than terminal shoots, and shoots
without flowers or flower buds. It is best to harvest
cutting material in the morning when the tissue is fully
turgid.
 
Use a sharp knife to cut 4-6" sections—the tip may or
may not be included. Plants that may be more difficult
to root often include part of the adjoining stem, the “he-
el.” Remove the leaves from the lower 1/2 of the
stem and if the leaves are large, cut the remaining
leaves in half to reduce transpiration. Keep the stems
moist if they will not be placed immediately in rooting
medium.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Easily rooted plants can be propagated by submerging
the lower half in a clean pot containing a well-draining
planting mix such as a mixture of 1/2 sand and 1/2 peat
or a mixture of 1/2 peat and 1/2 perlite. Stick the lower
1/3 to 1/2 of the cutting into the damp medium keeping
the bud terminal side pointed up and cover with a plas-
tic bag. Make sure that the bag is large enough so that
the leaves are not touched as condensation on the inside
of the bag will cause leaf rot. Plant stakes or wire can
be used position the bag correctly. Alternatively, a large
plastic bottle might be used as a cover. Place the pot in
indirect light. Be sure to keep the medium damp until
the cuttings have rooted. Bottom heat supplied by a
rooting mat helps root formation for difficult species as
does dipping the fresh cutting in commercial rooting
hormone powder.
 
How will you know when the cuttings are rooted? The
length of time required for rooting varies considerably,
with conifers generally taking the longest time. Howev-
er, you’ll be able to detect new growth. A gentle tug on
the stem met by resistance will tell you that roots have
formed. Carefully transplant to a pot with suitable
planting mix and grow until the plants have reached
sufficient size. I usually grow my plants in a nursery
section of the garden before planting them out in their
final location.
 
For more detailed information and illustrations, the
HAH Library has a copy of the highly regarded
“Making More Plants: The Science, Art, and Joy of
Propagation” by Ken Druse. You might also be inter-
ested in picking up your own copy of
“American Horti-
cultural Society Plant Propagation: The Fully Illustrat-
ed Plant-by-Plant Manual of Practical Techniques” by
Alan Toogood.