Quite often, I get calls on GardenLine regarding the propagation of specific plants.
Simple as I try to make it, the details often make it sound quite complicated. But exchanging cuttings with friends, especially if the cuttings are from rare or hard-to-find plants, is one of the most rewarding ways to add new and interesting items to your garden. Whether it's a favorite rose you have to leave behind when moving to a new home, that wonderful passion vine from Grandmother’s arbor, or that uniquely colored bougainvillea that you can’t seem to find at the nurseries anymore, it can be successfully started from cuttings. So, I've put together some simple steps to help you produce all the new plants you want by rooting stem sections cut from existing plants. First, you should know this process is easy. Surely you've seen Pothos ivy stuck in a glass of water on a window sill producing roots like crazy. While that is one way to root cuttings, it is definitely not the most efficient, especially when it comes to woodier plants. But you can see how easily those roots produce in plain water without any help. There are three cuttings categories ... semi-hardwood, softwood and herbaceous.
Semi-hardwood cuttings are usually taken from woody, broad-leaved evergreen plants, but they can also come from woody deciduous plants during the late summer or fall on shoots that are partially matured and having just gone through a flush of new growth. Hollies, camellias, roses, wisteria and similar platens are just a few varieties which can be rooted from semi-hardwood cuttings.
Softwood cuttings are taken from the tender new growth of woody deciduous or evergreen plants. Pyracanthas, coral bean, oleander, Arabian jasmine, spirea, and passion vine are among the plants that can be rooted from cuttings taken in the spring. Softwood cuttings may root easier than semi-hardwood cuttings, but being more tender, they can sometimes require a bit of extra attention during the rooting process.
You can take herbaceous cuttings from soft, tender plants like begonias, coleus, chrysanthemums or one of the many succulents. Herbaceous cuttings are rooted much like softwood cuttings, but the cut ends of plants like cacti and succulents which exude a sticky sap should be allowed to harden over for a day or so before they are planted. That will make diseases less likely to develop there.
Whether you are taking herbaceous, softwood or semi-hardwood cuttings, be sure they come from healthy, vigorously growing stock. Avoid cuttings from weak or diseased specimens. It is also a good idea to get permission from the owner if you spot a special variation on someone else’s property and feel you just have to get a cutting from it. (Just thought I'd warn you!) As you take cuttings, avoid using shoots from the outermost tip of any branch. While you don't want really old, extremely woody stems either, you don't want growing tips since they're more likely to quickly wilt. As a rule, stems with the diameter of a pencil are usually the best candidates for rooting. Make sure each cutting has at least two or three leaves or leaflets and is about four-six inches long.
The bottom cut on each piece is made just below the spot where a leaf joins the stem. Cut the bottom at an angle rather than straight across so you can tell at planting time which is the bottom end. (Cuttings sometimes get jumbled up, especially if you are collecting a variety of specimens away from your garden.) The early morning is usually the best time to take cuttings, but whatever the hour, be sure to keep everything you have taken wrapped in moist paper or cloth in a plastic bag until you can get them set in a rooting medium. Also, keep all your cuttings shaded and cool after you collect them ... a car parked in the sun can spell death for tender cuttings.
Once collected, cuttings can be rooted in a variety of containers. If you have a greenhouse where moisture and humidity levels can be closely controlled, flats are probably the easiest. Otherwise, large Styrofoam cups or coffee cans are fine. Just be sure to punch a few drainage holes in the bottoms so your cuttings won't become waterlogged. Large Styrofoam cups and one pound coffee cans can usually hold only one cutting per container, but larger cans or containers will hold more.
While there are just about as many formulations for rooting mediums as there are gardeners, a 50-50 mix of perlite and peat moss seems to get the job done dependably. Using fresh materials each time you root cuttings can help limit diseases which can kill your cutting before they root. Other growing media include sand, vermiculite, sterile potting soil or combinations thereof. And when re-using old flats, it is a good idea to rinse them out with a diluted bleach-and-water solution to kill any disease-causing organisms. Fill each container with the sterile potting medium and water thoroughly. Be sure peat moss is well soaked — it can be hard to moisten the first time it is used. Take an old pencil or small dowel and make one hole for each cutting. The holes should be deep enough so that the top half of each cutting will be left sticking out of the growing medium.
To protect from fungal diseases, and to encourage better rooting, dip the bottom end of each cutting in both a fungicide and a rooting hormone powder prior to setting it in the rooting medium. For best results, slightly moisten the bottom end of each cutting and dip it in an equal mixture of powdered fungicide and powdered rooting hormone. Rooting hormone can be found in garden centers, and the type containing indolebutyric acid usually works best on the widest variety of plants. Some rooting hormones are available already mixed with a fungicide, making their use even easier.
Gently set each cutting into its planting hole, taking care not to rub off the fungicide/rooting hormone powder. Firm the rooting medium around each cutting, then water gently once each container is filled with cuttings.
If you are not rooting cuttings in a greenhouse equipped with an intermittent misting apparatus, cover the top of each container with a plastic bag, plastic soda bottle (two-liter or larger) or glass. Secure this makeshift greenhouse tightly so moisture and humidity, crucial to rooting, will be trapped inside the container. Large rubber bands are good for attaching plastic bags to cups or coffee cans. Insert several straws around the edge of each container prior to covering to keep the plastic above the cutting as it roots.
Set your tiny “greenhouses” in a warm, bright spot but out of direct sunlight. Twice a week, carefully remove the covering and check the potting medium to be sure it is still moist. If it seems to be drying out, soak it gently, taking care not to disturb the cuttings. This is also a good time to remove any leaves which may have yellowed or fallen off. Do not leave the cover off any longer than you have to. Check your cuttings on a regular basis. Some plants root fairly quickly, sending out a few new leaves in just a couple of weeks. Others may take several months, so a large dose of patience is in order.
After your cuttings have put on new leaves, they no longer need the “greenhouse” effect. It will still be important, however, to leave the containers out of bright light and to water on a regular basis until the new plants are well-established and growing strongly. Then they may be carefully transplanted into larger containers for further development.