Carolyn Singer: Vegetative propagation: Save money by making cuttings
The Seasoned Gardener
May showers bring June flowers …? Certainly showers have brought lush foliage! But flowering of many perennials has been delayed with the extended cool temperatures.
Some of my summer vegetables are still in the cold frame, with no definite planting date in sight. Another unusual year for gardeners in the Sierra foothills!
Propagation of roses, shrubs, perennials and vines is at the top of the June list of priorities. It is important that the shoot chosen does not have a flowering bud. There are a few plants that are in bloom now, or are about to bloom (lavender is one), that will provide better cutting material in July or August.
Sometimes plants in bloom may have lower side shoots perfect for cutting. Look into the interior of the plant. Penstemon, Buddleia, and Thymus are examples of summer bloomers that may still provide excellent cutting material for vegetative propagation.
If possible, choose terminal shoots which have leaf nodes close together, whether opposite or alternate. Cut a length of stem that will allow two or more leaf nodes to be in the rooting medium, and one or two above. Cuttings should not be too long, especially during warmer weather. Some cuttings from small rock garden plants will be less than an inch in length.
Other cuttings from vines and ornamental shrubs with greater distance between nodes may be six inches or longer. These will need a tall container, but several long cuttings may be put in the same container.
Work early in the morning, in shade, and take only as many cuttings as you can handle in a few minutes. Cuttings wilt quickly. Do not allow any sun on the cuttings even early in the morning. You may take cuttings from a plant in the sun in the morning, but once taken, protect the cuttings from more sun during the propagation process.
If the plant is hydrated, watered within 24 hours prior to cutting, rooting is more likely to be successful.
The best medium for propagation of soft-wood cuttings is one-half perlite to one-half vermiculite. The materials are mixed in a container, and water is added to make a slurry. The material is then moved to the propagation flats and small containers. Excess water drains out through the bottom hole. Cells and pots are filled with a slight pressure to ensure that there are no air pockets. Do not press the medium firmly until after the cutting has been inserted. If cuttings are not easily inserted, a toothpick may be used to make a small hole.
Carefully remove all leaves along the stem except for the few which will remain above the medium. Determine how many leaves your cutting should have. The larger the leaves, the fewer should remain above the medium. If leaves are large, they may be cut in half to reduce potential for wilting. Reducing the leaf load by cutting a leaf in half during the propagation process will not delay the rooting.
Make your final cut below a leaf node. Dip the dry cutting stem into a rooting hormone (e.g. Rootone), allowing contact with the nodes, and shake off the excess. A cutting should not be wet or it will hold too much of the rooting hormone. Some cuttings root from the nodes, some from the bottom of the stem where the cut has been made, and some from hairs along the stem.
Work in the shade, and keep your propagated material shaded for a few days. Water with a light spray twice a day or more. If larger leaves still show sign of wilting after a few days, cut them in half.
Move the cuttings into bright light but no direct sunlight, and keep it in this exposure for two to three weeks. Shade cloth (30-40%) works well for protecting the cuttings in the first few weeks.
Remove any flowers that appear, no matter how tiny. At this stage you want the cutting to put all of its energy into growing roots. Clear covers or “humidomes” (Superior Growers Supply or Home Harvest Garden Supply), translucent row covers, or cold frames may be used to increase humidity.
After about five to six weeks, your cuttings should be rooted. Some take longer than others. Cut back the elongated terminal bud to stimulate root growth, and pot up the young starts into containers with a good potting mix. Your planting mix should not be hot, or high in nitrogen. If it is, it may kill these tender young starts.
It’s difficult to transport most cutting material. I have tried it in water, in damp paper towels, and even in an ice chest. What seems to work best is to carry supplies with me to the garden where I am gathering material and make the cuttings on site.
Most plants propagated in June and planted as soon as they are rooted may be ready as one-gallon plants for fall planting. Plant into a mix of compost, vermiculite, perlite, colloidal phosphate and oyster shell. Shade cloth (30-40%) is good protection for the first few weeks, allowing bright light but no damaging summer sun. After three weeks, grow sun-loving plants in the sun, and the shade-lovers in shade.
Propagating your own plants is an opportunity to save lots of money on landscaping, especially if you have friends who are willing to share plant material. In turn, you can share extra plants with others. When you purchase a plant, take cuttings (if possible) to ensure a backup supply. But ask permission before you help yourself to cutting material from that unusual shrub in an old garden, the plant you never see for sale in the nursery.
Carolyn Singer has gardened organically in Nevada County since 1977. She is the author of the award-winning “The Seasoned Gardener, 5 decades of sustainable and practical garden wisdom”, and two volumes of “Deer in My Garden” (deer-resistant plants), available locally. Send your gardening questions and comments to firstname.lastname@example.org. Check out her website at carolynsingergardens.com.
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