1 - Layering is sometimes easier than propagating plants from cuttings.

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.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

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