Rooting Hardwood Cuttings

Plants That Produce

Rooting Hardwood Cuttings

By Richard Frost

As I began to write this column, several of you called me with inquiries about the Pomegranates listed in last month’s column^†. A few of them are available now at San Diego area independent nurseries, and many more will likely be available next year. As an alternative: if you happen to know someone with a variety you really like the taste of, then you can make clones of it by rooting hardwood cuttings.

Before getting into procedural details, I’d like to remind you that cuttings may be rooted from several – but not all varieties of plants. So for example: Pomegranates, Peaches, Roses, plus Figs and Papayas are plants which are easy to root. As a counterexample: Persimmons will rarely if ever propagate by rooted cutting. For a more details on applicable plants, see “Plant Propagation” edited by Alan Toogood, published by the American Horticultural Society.

The optimum time to select cuttings from a plant is in the late winter or early spring when the nodes on hardened stems from last-year’s growth are swelling. The worst time is in the fall when some plants are cycling down into dormancy. For most plants, any time in between these two periods also works fine. Use clean tools and containers to avoid introducing unwanted disease.

Select straight “hardened off” stems 16 to 20 inches long and 1/4 to 3/8 inches thick at the base (point of cutting off plant). Don't select a branch with fruit on it unless you are really desperate. Cut the base straight across, and cut the growth tip off at a 45-degree angle. Remove any flowers and fruit (ouch!). If there are leaves, remove all leaves 3/4 of the length from the base and cleanly clip off side branches (until you are an expert). Cut all remaining leaves in half width-wise, so the half with the leaf tip is removed.

To plant your cutting, choose a soil medium that provides aeration. Straight ground coir (coconut fiber) is excellent, but so is rock wool, or just a peat-based potting mix that contains perlite. Put the soil medium into a pot that is 8 inches high, filling it completely. Then wet it thoroughly and let it drain. Press the soil down moderately. You probably now have a pot of damp soil that is about 1-inch below the lip – as desired. Now take a chop stick or screw driver (etc.) and make a hole in the pot for the cutting, no deeper than 1.5 inches from the bottom.

It is advisable to use a rooting gel, liquid, or powder – or a 50/50 mix of water and seaweed extract (contains gibberellic acid). Dip your cutting in the rooting solution almost up to the point of the soil line and place it in the hole. Then press the soil in the pot gently to close the gap around the stem.

Place the pot(s) in about 30% to 40% shade – continuously during daylight hours. The soil temperature should be between 70^º (F) and 85^º, and the air temperature between 60^º and 80^º. The soil cannot dry out -- or be soggy. The stems often begin sending out new growth before any significant roots have developed, so be patient! Give them at least 6-8 weeks before checking the holes in the bottom of the pot for roots.

SDHS member Richard Frost is a certified edible gardening nut. ^†For copies of past articles and more information, please see www.PlantsThatProduce.com.

Reprinted with permission from August 2009 "Let's Talk Plants," the newsletter of the San Diego Horticultural Society, www.sdhortsoc.org