Yard
and Garden
August
1, 2015
Q. I
have tried to grow new trumpet vines and grapes from trimmings from the older
plants in my garden. I am not having much success. Do you have
suggestions?
A. Success
growing new plants from cuttings take from grapes and trumpet vines depends on
several factors. Timing and the status of the stems used for cuttings is
important. Use of rooting hormones may also greatly increase your chances
for success. Good soil and adequate moisture are also important.
Grapes are usually pretty easy to grow from cuttings if they cuttings are
placed in the garden or into pots of good potting soil quickly after they are
cut. They will often grow new roots if the cuttings are just placed in
water. Do not let the cuttings dry before planting them. You can put them
in water immediately after cutting and then put into soil a day of two later if
necessary.
Hardwood cuttings are those that have become woody and are often the cuttings
collected in the later winter or early spring before growth begins.
Rooting hormone placed on the basal portion of the cutting will help, but is
not necessary. It is critical, however, to keep track of the “proximal”
and “distal” portions of the stem. The proximal end of the stem is that
part that was closest to the soil when the cutting was cut. Many gardeners
make sure to make a slanted cut when they cut the stem from the parent plant to
clearly identify the proximal end. This proximal end must be the end put
into the soil. If the distal portion of the cutting (the opposite end) is
placed in the soil, it will not grow roots even if treated with rooting
hormones. The plant knows the difference between up and down!
Softwood cuttings are new stems collected within about a month after growth has
begun. The stems are very tender and often form roots fairly easily - if
they do not dry out and die before roots form. Their tissues are soft and
not as completely differentiated (cells types determined) as in other types of
cuttings. These are identified by the fact that the outer layers of the
stems are easily punctured by a thumbnail.
Semi-hardwood cuttings are a little older than softwood cuttings. Their
epidermal tissues have begun to harden and resist damage by a thumbnail.
There internal cells are also more differentiated and may be more resistant to
forming roots. However, for some plants these are actually the easiest
cuttings from which to start new plants.
At this time of year another useful technique is to use a process called
layering. In the process of layering, the stems are induced to form roots
before they are severed from the parent plant. Grapes and other vining
plants are easily layered because their stems may be easily bent to the
ground. These stems should be wounded by scraping the bark, cutting
through the outer layers, or by slicing partially through the stem before
burying it in the soil. The wound causes sugars produced in the leaves to
accumulate at the point of the wound and to feed development of roots at that
point. After a few months new roots should have formed and the new plant
may be separated from the parent plant and transplanted, or just allowed grow
where it formed. It may also be induced to form roots in a large pot
which will make transplanting less traumatic for the new plant.
The type of layering described above is called “simple layering”. There
are other forms of layering that are useful for other plants, but in the case
of vining plants like grapes and trumpet vines, simple layering is an easy and
successful way to start new plants when cutting propagation fails.
Send
your gardening questions to Yard and Garden, Attn: Dr. Curtis Smith, NMSU
Agricultural Science Center, 1036 Miller Rd. SW, Los Lunas, NM 87031. You may
also send to cwsmith@nmsu.edu or leave a message at https://www.facebook.com/NMSUExtExpStnPubs. Curtis W. Smith,
Ph.D., is an Extension Horticulture Specialist, retired from New Mexico State
University’s Cooperative Extension Service. NMSU and the U.S. Department
of Agriculture cooperating.
