“The Backyard Gardener” by Kelly Orzel (Lyons Press, 2017) is a comprehensive gardening guide that offers useful advice to help readers build their confidence and know-how. This excerpt from chapter 2 shares how to propagate your garden.
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Cuttings are underrated as a propagation method. It’s as natural as breathing for some plants to root—they’ll do it without any help from you. Have you ever put mint or basil in a glass of water only to see white hair roots develop within a week? Other plants need a bit more inducement to root. The primary motivation for taking cuttings over seeding is to preserve the exact characteristics of a plant that does not comes true to seed. Or, if germination is particularly spotty, it’s often easier to take cuttings as a little extra insurance so you don’t lose any of your favorite performers. Sometimes this practice is referred to as vegetative, or asexual, propagation because there is no seed making involved in creating offspring. Cuttings are like cloning — you’re using one piece of a living organism to make an identical replica. For herbs like French tarragon and lavender, this is the only way to get true plants, but for others like bay leaf it is a shortcut. Bay takes three to twelve months to germinate and another two to three years growing in a pot before it can be planted out, but a cutting will root in three to six months … it’s really a no-brainer which method to use.
For the best chance of success, always choose shoots from thriving, healthy plants with fresh growth and use clean, sharp snips or knife. You can take root, leaf, or stem cuttings, but the most common is stem. Then there are softwood, semi-ripe, and hardwood type cuttings, but this refers more to when the shoot is being cut rather than the part of the plant being used. Softwood cuttings are taken from new growth in spring through early summer and are the easiest to root. They are your “most likely to succeed” type of cutting, but you have to be aware not to let them dry out. When taking cuttings, I carry a large zip lock bag that I periodically mist and keep closed to keep the cuttings moist. Semi-ripe stems look as if their growth has begun to slow—the stem is becoming more woody. Cut this in late summer, keeping in mind that these will take longer to root than fresh softwood cuttings. Hardwood cuttings taken in late autumn through winter off deciduous trees and shrubs should root by the following spring.
Softwood and semi-ripe cuttings are taken the same way, cut four- to-six-inch lengths with four to six sets of leaves at an angle from the stem tip, carefully removing the lower two-thirds leaves so as not to exhaust your new roots. If you tear or squish the stem, it may make rooting difficult and invite disease. Then make a new cut just below a bare node near the bottom. Shaving a sliver from the side of the bark of semi-ripe cuttings can stimulate the rooting cells when the wound calluses over. Dip the bottom and barren nodes of the cutting into rooting hormone to promote root development.
Just be sure to pour the powder you’re using into a separate dish and discard afterward to avoid contamination with your supply. Use a soil mix similar to what you used for seed starting—garden soil is too heavy. Also, mixing a few teaspoons of seaweed meal and bonemeal into the soil will get your cutting off to a good start without generating too much top growth from nitrogen fertilizers. Gently insert the cutting into your soil blocks, seed trays, or cells until the remaining leaves sit above the soil and then firm at the base. Keep the soil moist and use plastic bottles, clear domes, plastic bags, or kitchen cling wrap to maintain the humidity, venting daily. Do not let the plastic touch the leaves. Heat mats are useful in accelerating rooting. Most cuttings will root in three to six weeks, sooner if kept in a greenhouse. You’ll know when your cuttings are rooted by lightly tugging on them; if they resist being pulled, they are rooted.
Hardwood cuttings are typically six- to-eight-inch, pencil-thin lengths cut at an angle below a node at the bottom. Make another cut at the top, this time straight, above a node. The straight and slant cuts will help you differentiate the top from bottom of the cutting. Wrap branches in damp paper towels to maintain freshness until you’re ready to plant. Smother the bottom of each in rooting hormone and insert two-thirds to three-quarters inch deep into a pot filled with soil mix, water, and place in a cold frame or greenhouse over the winter. Remember to check periodically to ensure your cuttings are moist throughout the cooler weather. For gardeners in warmer climates (zone 8+) you can keep your cuttings outside until the spring, but they may take longer to root. Over the next six to eight months you should see new growth. Tug to make sure they are rooted, and it’s now time to transplant into the garden.
Check regularly for water and moisture. The soil medium should be moist, not wet; otherwise you will see a disease called Black Leg. Basically this is rot, starting at the base and going up. You will know you have this if you see the bottom of the stem turn black. It is important to maintain humidity, hence the plastic domes or bags, but if the plastic touches any leaves it will invite mildews, rots, and disease. Also, you should vent periodically to prevent condensation buildup on the interior of the plastic.
Leaf cuttings are typically successful for tropicals and houseplants. Similar to softwood and semi-ripe, cut one leaf with a one- to-two-inch long stem and stick it into a moist potting medium at an angle until the leaf is above the soil line. Cover with clear plastic to maintain humidity as you would with other cuttings.
Root cuttings are different because they are taken when the plant is dormant. At this time of year the roots are full of food and carbohydrates. Dig up one side of the plant, exposing the roots (this won’t disturb the parent plant), and cut two- to-six-inch, pencil thick lengths close to the plant base. Cut the top straight across and the bottom at an angle, so you can easily find the top. Bundle and store the roots in moist potting soil or coarse sand in a dark spot at 40 degrees Fahrenheit for three weeks. Once removed, use a dibble or pencil to make a hole in your potting mix, planting the slanted end down such that the top is just covered with soil. Store in a cool location where they won’t freeze until spring, then harden them off and plant once they are rooted and have formed leaves.
Cutting Mix Recipe
Moistened 50 percent perlite (or coarse, builder’s sand) plus 50 percent peat and/or coir with seaweed meal (or liquid seaweed).
Tips for Faster Rooting• Choose thinner stems — they root more quickly than thicker stems.
• Take cuttings in early morning when the plant is still turgid and less likely to dry out.
• Select young, strong branches.
• Side shoots root better than terminal.
• Remove any flowers.
• Cut any large leaves in half. They will still photosynthesize but won’t exhaust the roots to do so.
• Use a root hormone powder, particularly for semi-ripe and hardwood cuttings.
• Employ a heating mat underneath for more rapid rooting.
• Cut the base at a slant to expose more stem surface for root development.
• Dip your cutting tools in 10 percent bleach solutions to avoid disease transmission.
These are the lazy gardener’s cuttings. Essentially you train one or more stems to root while still attached to the plant, then separate them using a sharp knife or pruners. The best time to do this is while the plant is actively growing.
You will need some open garden space around the plant you want to layer. Loosen the soil nearby where a flexible stem will come in contact with the soil. Find one or more long, healthy stems and strip the leaves where it meets the ground, leaving a significant amount of leafy growth so the plant can continue to photosynthesize. Using a sharp knife cut the underside of the stem below a node one-third of the way through. Situate the stem such that the wound stays open when buried under the soil. Anchor with landscape staples, pins, or a heavy rock. You can stake the green stem/growth to help the plant grow upright if you like. Water regularly and keep an eye out for new growth. Sever the new plant once it’s thriving on its own. This can take time — anywhere from a few weeks to a year. Although you can leave it in place for another season, I prefer to dig it up and move it to another spot in the garden so the roots don’t get intertwined with its parent’s. Another quick layering method is to insert the growing tip of a branch into some bare adjacent soil. Bury the tip and secure. Again, you can sever once the new plant is growing vigorously.
Perennials come back year after year, but oftentimes if they are not divided periodically, their roots get congested, resulting in a weaker plant and reduced flavor. Dividing gives these plants the room to grow, flourish, and extend their lives. The general guideline is to divide every three to five years, replanting the newest, hardiest sections and ensuring that each division has at least one growing point and its own root system. Dividing works for plants with fibrous root systems and should ideally be performed in the spring or fall. Woody plants cannot be divided. I prefer to wait for a cool day after a rain so the soil is a little looser and the plant is less likely to dry out. Prepare clean one-gallon pots or make a hole in the ground, depending on whether you plan to share and swap plants with friends or transplant divisions in the garden. Then you need to dig up the plant, making sure you get the entire root ball. Give yourself plenty of space and take your time.
After you dig the plant up, lift it using a fork and divide. You can separate your herbaceous perennials a few ways. Smaller plant roots can be teased apart with your fingers or hand forks, but some of the larger ones I find easier to slice through using a spade or saw. When my husband and I were newly married, his grandmother offered to share her lovely, but way overgrown, hosta collection with us. The crowns were so tight that it took an ax to separate them. So if you need to, think outside the box. (By the way, our hostas look beautiful!)
Replant your divisions in the garden immediately to avoid drying out, or with some loam and compost in a pot. Water-in well and maintain steady moisture until the plant is established. Your old plants will look much happier and appear rejuvenated.
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This excerpt is reprinted with permission from The Backyard Gardener by Kelly Orzel, published by Lyons Press, 2017. Buy this book in our store: The Backyard Gardener.