Multiply Your Plants With Propagation
By Penny Pawl
NAPA VALLEY, Calif. — I love propagating plants, and I have used several methods with success. As I walk around my garden, I can see the results of this pastime. Some of my propagating efforts have grown into full-size plants.
When I am pruning, I often save some of the pruned parts and attempt to make new plants through a process known as vegetative propagation. My first attempts at this method were under the guidance of John Hoffman, a retired Napa arborist who was among the first certified Napa County Master Gardeners. John told me to take cuttings of the plants I wanted to reproduce and plant them in a mixture of half sharp sand and half pumice or perlite. This mixture drains well but stays damp so cuttings don’t dry out.
This method can take a while, depending on the type of plant. I have, on occasion, put a large bottle over the top of the pot to retain moisture.
Many people dip the cut end of the plant in rooting hormone, but I have found that step unnecessary. When I can tug gently on the cutting and feel some resistance, it has probably rooted and is ready for potting in well-drained soil. Not every cutting will root, in my experience. I can treat two identical cuttings the same, yet one will fail and one will root.
I reuse the sand-pumice mixture and have cuttings going in and out over time. I keep these pots filled with starting mixture in the greenhouse during winter and in a shady spot during summer.
Many plants are patented. If they are reproduced vegetatively and sold, the patent-holder is entitled to payment. This is not a concern for me as I give away my extras.
Another propagation method I like is via root cuttings, which works well on elms and maples. When pruning plant roots, take a piece of live root that has tiny feeder roots and plant it in the rooting medium cut side up so that the feeder roots are buried. The new growth will emerge from the cut end. If you inadvertently plant the wrong side up, you will likely have a failure. In time, the cut end will sprout new leaves and more roots, and you will have another plant ready to pot.
Air-layering also works for propagation, although it takes a lot more time. It is most suitable for hardwood bushes or trees. I have seen it used in Japan on large pine trees. I successfully propagated a Japanese maple via air-layering in 1994, and it is still growing well. The trunk was about 3 inches in diameter when I air-layered it, and now it is a full-size tree.
To succeed with air layering you need to pay attention to proper technique. It’s difficult to describe the method, but you can find good videos and websites to guide you. This site is one that clearly explains how to use air-layering to propagate a fruit tree.
A few years ago, while reading about propagation, I learned about the plant-propagation machines known as cloners. I now own three, and two are full of cuttings all the time. I have done both hardwood and softwood cuttings in the cloners, which rely on hydroponics, continually washing the stems of the cuttings with water. The cloner comes with a small pump, and I check these pumps daily to make sure nothing is plugging them.
It is amazing how quickly the softwood cuttings root. I once put a geranium in the cloner and left home for two weeks. When I returned the plant had enough roots to go into its own pot. Using a cloner, I have had success propagating elms, maples, milkweed, Verbascum, salvias and many other plants.
To take a cutting for propagation, I look for new tip growth. I cut a piece 10 to 12 inches long, measured from the cut to the growing tip, and strip off the bottom leaves. I make the cut on the diagonal to expose as much of the green cambium layer as possible. Usually the new roots push from that part. However, on some plants, roots emerge from the stem where leaves were removed. If new leaves push from the stem, I remove them.
There are other propagation methods that I don’t use. One practice involves bending a stem (or branch) of the plant to the ground and then topping the stem with soil. Given time and good conditions, this stem will develop roots and can then be separated from the mother plant.
What do I do with all the plants I propagate? Many go into the ground, some into pots and others I happily give to friends.
Become a Master Gardener Volunteer: UC Master Gardeners of Napa County is now accepting applications for the Class of 2025. Visit napamg.ucanr.edu to read the informational brochure; then register to attend a mandatory information session for applicants. Application deadline is 5 p.m. on Sept. 25.
Workshop: Join UC Master Gardeners of Napa County for “Succulent/Dry Garden: Double Your Pleasure — Double Your Fun” on Saturday, July 27, from 10 a.m. to noon at Las Flores Learning Garden, 4300 Linda Vista Ave., Napa. Do you know the five most common ways succulents reproduce? Learn their secrets and how you can increase your plant collection or add to your low-water landscape through succulent plant propagation. Register here.
Library Talk: Join UC Master Gardeners of Napa County and Napa County Library for a talk on “Fabulous Ferns, Indoors and Out” on Thursday, Aug. 1, from 7 to 8 p.m. via Zoom. Ferns are an accommodating family of plants ranging in size from tiny to behemoth. Some species grow in air and others in water, as well as in just about any type of soil. Enjoy an overview of these remarkable plants and find the perfect one for your space. Register here to receive the Zoom link.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 a.m. until 1 p.m. at the University of California Cooperative Extension Office, 1710 Soscol Ave., Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description. For best results attach a photo.
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Penny Pawl is a UC Master Gardener of Napa County.
What an interesting article. I always learn something from you Penny! I have never heard of cloner machines, but I am going to do some research on these. Thank you for yet more inspiration!