Creating New Plants From Cuttings
If you are a typical gardener, then you are probably experienced with growing new plants from seed. Seeds are an easy and inexpensive way to grow lots of new plants, particularly annuals. In some cases, seeds may be the only viable way to propagate certain plant species. Unfortunately, not all plants come true from seed, particularly if the plant in question is a hybrid or cultivar. As a result, some plants grown from seed may differ from the parent plant, which can be very disappointing.
Another way to create new plants is to divide the roots of a mature plant into several separate plants. This method works well for many perennials with fibrous root systems. However, you must wait until the “parent” plant is mature enough to make root division feasible. On average that’s about three to five years for the typical perennial. Also, plant species with tap roots or woody root systems, such as shrubs, trees, and some perennials, cannot be readily divided into new plants without seriously damaging the parent plant.
VEGETATIVE PROPAGATION FUNDAMENTALS
Vegetative propagation (asexual propagation) offers an alternative to creating new plants from seeds or root divisions. It involves taking a part of a plant, such as a stem or a leaf, and manipulating it so that it regenerates into a new plant. One advantage of vegetative propagation is that the new plant will be a clone of the “parent” plant and therefore identical, regardless of whether the parent is a species or cultivar. Another advantage is that the new plants will mature faster and flower sooner than plants grown from seed. A third advantage is that vegetative propagation can be done sooner than root division.
Vegetative propagation has been around for literally thousands of years. It is a cheap, easy, satisfying way to create new plants. Moreover, it may be the only viable means of retaining and perpetuating the characteristics of some species or cultivars.
Several broad types of vegetative propagation include:
- Cuttings – severing a part of a parent plant and rooting it to create a clone of the parent.
- Layering – rooting a part of the parent plant and then severing the new plant from the parent.
- Grafting – joining two plant parts from different varieties so that they function as one plant.
- Budding – joining two plant parts from different varieties so that they function as one plant.
Because vegetative propagation is a fairly complex subject, this article is limited to a discussion of cuttings only.
FACTORS THAT IMPACT THE PROPAGATION SUCCESS RATE
If you are new to vegetative propagation and want to give it a try, there are a number of factors that can influence the success rate of your propagation efforts. Before you start a propagation project, consider the following first:
The health and overall condition of the parent plant. Choose a healthy, disease- and insect-free plant with characteristics you want to replicate. Avoid taking cuttings that are in flower or in bud. The cutting needs to put its energy into establishing a strong root system rather than supporting flowers.
The day before you plan to take cuttings, water the parent plant so that it is fully hydrated. Take cuttings of soft-stemmed (green) plants in the morning when the plant is well hydrated. This is not necessary for dormant woody cuttings.
Moisture. The soil or potting medium that you use for rooting your cuttings needs to be thoroughly moistened but not soggy. Apply water slowly so that it is uniformly distributed throughout the medium and then check it to make sure it is not dry in the middle.
Light: Diffused sunlight is generally sufficient for rooting cuttings. Low light levels cause the roots to root slowly. If the light level is too intense, it can stress the cuttings and potentially burn them or cause leaf drop.
Humidity: High humidity is needed to offset the amount of moisture lost through transpiration. Until cuttings develop roots, they are unable to take up moisture from the potting medium. Covering the pot or propagation tray with clear plastic wrap or a plastic bag causes condensation to form on the underside of the plastic and cuts down on the amount of moisture lost to the atmosphere. In conjunction with humidity, air flow around the cuttings needs to be taken into consideration. The plastic covering should be placed far enough away from the cuttings to avoid impeding air flow. An easy way to do this is to place stakes of some sort (twigs are great for this purpose) around the cutting so that the plastic rests on the tips of the stakes and not on the cuttings themselves.
Temperature: While the ideal root zone temperature for rooting cuttings is about 70° to 75° F, it is important to avoid extremes in temperatures. Cuttings that are being rooted in the winter months can tolerate cooler temperatures but, if in doubt, provide bottom heat from a seedling heating mat.
Timing. The time of year plays an important role in the success of cuttings. For example, some plants should be propagated vegetatively only when they are actively growing in spring and summer. Other plants must be in a dormant stage. Yet other plants (mostly houseplants) may be propagated at any time of year.
PROPAGATION TOOLS AND SUPPLIES FOR ROOTING CUTTINGS
Fortunately, taking cuttings from plants does not require any special tools or techniques. However, cuttings need to be potted quickly to keep them from wilting or drying out. So plan what tools and supplies you need and have them ready in advance of taking cuttings. Here’s a suggested list of items you may need:
- Scissors, a sharp knife, or razor blades for cutting soft stems and leaves. Sterilize tools before using them for cuttings.
- Shears or pruners for taking cuttings from fibrous or woody stems.
- Pots or propagation trays for rooting new plants. Sterilize and fill with potting soil to within about one-half inch of the top edge.
- Trays for holding pots. This is optional, but if you plan to fill a lot of pots with cuttings, it’s easier to move pots around if they are on a tray.
- Potting soil. Choose a potting medium that provides optimum aeration, drainage, and moisture holding properties. Mixtures vary, but most include some combination of peat moss, perlite, vermiculite, or sand.
- Plastic bags or plastic covers to place over pots to create a humid environment while cuttings are developing roots.
- Water to moisten the propagation medium.
- Rooting hormone. This is not essential, but it tends to give better rooting results because it increases auxins (plant hormones located in the tip of a stem that encourage elongation), which can help the plant grow stronger roots.
- Pencil, dowel, chop stick, or other pointed instrument for making holes in potting soil in which to insert plant stems. The pencil (or pen) is also needed for writing on labels.
- Labels. These may not be needed unless you are rooting cuttings from several plant species and need to tell them apart.
TECHNIQUES FOR TAKING CUTTINGS
Three major vegetative propagation techniques by cuttings include stem cuttings, leaf cuttings, and root cuttings.
This is the most common propagation method for many herbaceous and woody plants. A few general rules apply to taking stem cuttings. To enhance your propagation success rate, take the cuttings:
- From the correct part of the stem for the plant being propagated and for the time of year. Depending on the species, this refers to using a stem tip cutting, which is tender, versus a more mature (woodier) part of the stem.
- From younger plants rather than from older, more mature plants (if you have that option). Younger plants generally root better.
- From side (lateral) shoots, which root better, rather than cuttings from end (terminal) shoots.
- At the appropriate time of year. Some plants must be actively growing in order to respond well to cuttings, while others need to be in a dormant state.
Based on the growth stage of the parent plant, stem cuttings fall into the following broad categories: herbaceous, softwood, semi-hardwood, and hardwood.
Herbaceous cuttings. Many herbaceous (non-woody) plants such as annuals, perennials, herbs, and houseplants can be easily propagated from stem tip cuttings. One quick and easy way to propagate an herbaceous cutting is to root it in water, but that method doesn’t work for all plants. A preferred method is to plant the fresh cutting in a potting soil medium.
Coleus, dahlia, chrysanthemum, Nepeta (catmint), Agastache (hyssop), thyme, mint, lemon balm, sage, oregano, basil, ivy, and philodendron are just a few examples of plants that respond well to stem tip cuttings. These plants have tender, immature growth that tends to dry out quickly. Therefore, an artificially controlled environment is needed to moderate temperature and humidity long enough for the cutting to develop roots. Cuttings from these plants may be started any time of year, but spring or summer are best when the plants are actively growing.
How to propagate a stem tip cutting:
- Cut off a 2- to 6-inch long portion of a stem that has no flowers or buds on it. If your only choice of plant material happens to be in flower, snip off all flowers and flower buds.
- Trim off any side stems and lower leaves, leaving no more than one or two sets of leaves.
- After removing the lower leaves, trim the stem to just below a leaf node. That’s where the new roots and shoots will emerge from the stem.
- If using a rooting hormone, dip the end of the stem into the hormone and gently shake off any excess.
- Make a hole in the moist potting medium with a pencil or other pointed object.
- Insert the stem into the hole, making sure the stem wounds are covered by the potting medium.
- Insert the container in a tent that is loosely fashioned from a plastic bag or in a plastic container with a clear lid. If using a plastic bag, close it with a twist tie and make sure the leaves are not touching any part of the bag. If necessary, insert a couple of small stakes in the container to hold the plastic bag away from the foliage.
- Set the bag in a brightly lit area (but not in direct sun).
- Keep the potting medium moist but not soggy and open the plastic bag or enclosed container occasionally to allow some air circulation.
- Once the cutting starts to show new growth, gently tug on the stem to see if it has rooted. If it feels firmly anchored in the potting medium, gradually open the plastic bag to increase ventilation and decrease humidity. This will encourage the new growth to harden off for transplanting later.
Softwood cuttings: This is the soft, new growth that is produced at the tip of a woody stem on a shrub, vine, tree, or woody-stemmed perennial. The cuttings should be made just as the season’s new growth begins to harden. This stage occurs for many woody plants in late spring through mid-summer. The stem should snap easily when bent and the leaves should be graduated in size with both larger, older leaves and smaller, newer leaves. To propagate softwood cuttings, follow the same steps as for herbaceous cuttings above.
Semi-hardwood cuttings: Many deciduous woody shrubs, trees, or vines can be propagated from semi-hardwood cuttings in mid-summer to early fall. The cuttings should be taken from the current season’s growth after it has matured. Many broadleaf evergreens, such as boxwood, holly, and Rhododendron, are examples of plants that respond well to semi-hardwood cuttings. These semi-ripe cuttings need the same temperature and humidity-controlled environment for rooting purposes as the herbaceous and softwood cuttings described above.
Hardwood cuttings: These are taken from dormant sections of mature woody shrub or tree stems in late fall, winter, or early spring from shoots that grew the previous summer. Hardwood cuttings are the easiest of the four categories to propagate. Although slower to root than other types of cuttings, they are robust and require few, if any, environmental controls to ensure their survival. The wood should be firm at this stage and not easily bent. Most deciduous shrubs and needled evergreens respond well to hardwood cuttings.
How to take a hardwood cutting:
- Cut a 4- to 8-inch long branch from a dormant woody plant using a straight cut at the bottom and just below a bud or pair of buds.
- Trim off any smaller branches from the cutting.
- Snip off the top of the branch using an angled cut. This helps water run off the cutting and helps prevent rot. It also indicates which is the top and which is the bottom end of the cutting.
- If using rooting hormone, dip the bottom including the bud or buds into the hormone compound.
- Make a hole (or holes if you are rooting multiple cuttings in the container) in moist potting medium with a pencil or other pointed object just slightly larger than the branch cutting. This prevents rooting hormone from rubbing off the cutting.
- Insert the cutting 2- to 4-inches deep into the holes. Ideally, just the top bud or buds should be exposed.
- Place the potted cuttings in a protected area outdoors. Water the dormant cuttings only as needed to keep the soil just barely moist.
- As weather warms up in early spring, start watering the cuttings.
- Move the pot into sunlight and keep the cuttings watered.
- Don’t plant the rooted cuttings until fall to allow time for plenty of roots to develop over the summer.
Leaf cuttings are often used to propagate house plants. While the cuttings can be taken any time of the year, spring to early summer is generally best when the plant is actively growing. With leaf cuttings, adventitious buds, shoots, and roots form at the base of the leaf and develop into new plants. The parent leaf typically disintegrates after the new plant is formed.
Depending on the species and leaf structure, plants may be propagated from leaves using several methods, including whole leaves with petiole, whole leaves without petiole, split vein cuttings, and leaf sections. As with herbaceous stem cuttings, leaf cuttings resulting from these methods need to be placed in a temperature and humidity-controlled environment while shoots and roots are forming.
- Whole Leaf with Petiole. A petiole is the slender stalk that attaches a leaf to a stem. Not all leaves have petioles, but for those that do, the trick to rooting the leaves is to make sure some petiole tissue is attached. Otherwise, the leaf will not root. When rooting a leaf with a petiole, sever the leaf and as much as an inch of the petiole. Insert the cut end of the petiole into the potting medium. This type of propagation will result in one or more new plants that form at the base of the petiole. African Violets and Gloxinias are examples of plants rooted this way.
Whole Leaf without Petiole. Some plants have leaves that lack a petiole and are attached directly to the plant stem. These plants are capable of forming new roots and buds directly from the leaf. Jade plant (Crassula), Kalanchoe, Sanseverias, Echeveria, and Sedum are examples of such plants. Simply cut or snap off a leaf right at the base where it is attached to the stem. Place the leaf on a tray or other flat, dry surface to allow the cut to dry and callus over. This can take a few hours to several weeks, depending on the species and the thickness of the leaf. Once the callus is formed, place the leaf on top of a loose, well-draining potting medium and angle the leaf so that the cut end is just barely covered with soil. Roots usually begin to form within about 3 weeks.
- Split vein cuttings. This method is often used to propagate begonias. Remove a leaf from the plant and cut off the petiole as close to the leaf as possible. Turn the leaf over and use a very sharp, sterile knife to slit the veins in several places. Try not to damage the adjacent leaf cells. The less damage you do, the greater your chances of successfully growing new plants. Place the bottom side of the leaf directly against moist potting medium. If the leaf wants to curl or lift up, place several pebbles or other small weights on the edges of the leaf to stabilize it and hold it in contact with the potting medium.
- Leaf Sectioning. This fourth method for propagating from leaves sounds a bit drastic because it requires you to mutilate the leaf. This is an easy way to get multiple copies of a plant from a single leaf. As described above, the objective of the split vein cutting method is to sever the veins of the begonia leaf while doing as little damage as possible to the surrounding leaf tissues. With leaf sectioning, the objective is to do the opposite. Instead of severing the begonia leaf veins, use scissors to cut the leaf into wedges. Each wedge should contain at least one vein. Position the wedge vertically so that the center point is in contact with potting soil. You may need to prop up the leaf against the side of the pot to help keep the severed edge in contact with the potting medium.
Leaf sectioning also works with more fibrous leaves such as those found on Sansevieria (snake plant) or Eucomis (pineapple lily). For these plants, use a sharp pair of scissors or a knife to cut off an entire leaf at the base. Cut the severed leaf horizontally into 2-inch pieces. Make sure you keep track of which is the top edge and the bottom edge of each cutting. Dip the lower edge in rooting hormone (optional) before inserting it about 3/4-inch into the potting medium. If you plant it upside down, it won’t sprout.
While stem and leaf cuttings encourage the plant to develop new root systems, root cuttings may respond differently. For most plants, root cuttings encourage the development of 2 or 3 new stems first, after which the stems develop new root systems. The original root cutting eventually disintegrates. This method is an excellent way to produce a lot of new plants quickly and with very little effort.
For best results, root cuttings should be taken in late fall, winter, or very early spring from 2- to 3-year old plants when they are dormant. This minimizes stress on the parent plant. That’s also when the roots have plenty of stored nutrients, but new growth hasn’t begun yet. Oriental poppies (Papaver orientale) and bleeding hearts (Dicentra species) are two exceptions that may be propagated by root cuttings in midsummer, several weeks after flowering has finished, as opposed to winter.
The technique for rooting a thin-rooted plant such as garden phlox differs from the technique used to root plants with thicker roots. To take a root cutting from a thin-rooted plant:
- Dig up the entire plant and rinse off the roots so that you can easily see the plant crown and root structures.
- Snip off a root (or roots) as close to where it joins the crown as possible.
- Snip the root into 1- to 2-inch long sections.
- Position the snipped sections horizontally about 1 inch apart on top of moist potting medium.
- Cover the roots with 1/2 inch of potting medium and moisten.
- Place the container with the cuttings in a plastic bag or under a humidity dome or under a pane of glass and place under grow lights.
- Keep the soil evenly moist but not soggy.
- Replant the original plant.
- After new growth is visible from the cuttings, remove the covers. Give them sufficient light for their growing needs and keep soil moist but not soggy.
- The plant will be ready to transplant into the garden once several sets of leaves have developed.
To propagate thicker roots from a shrub, tree, or vine:
- Dig carefully around the base of the parent plant to expose some of the roots.
- Select roots that are about the thickness of a pencil and cut with pruning shears or a sharp knife. Make the cut as close as possible to where the root emerges from the crown of the plant. Take only a few roots from the parent plant. Otherwise, it may not recover from the loss of so many roots.
- After you take your cuttings, replace the soil over the root ball.
- Cut the harvested roots into 2- to 6-inch long sections. As you cut, make a straight cut on the end that was closest to the center of the plant. Make a slanting cut at the other end.
- Insert the entire cutting vertically in moist potting soil with the slanted end down and the straight end just below the surface of the soil.
- Keep the soil moist but not wet while the cutting is rooting.
- Once you see the roots emerging through the pot’s drainage holes, you will know that it is ready for transplanting into the garden.
Examples of plants that respond well to root cuttings include: Barrenwort (Epimedium), bleeding heart (Dicentra spectabilis), Blue Star (Amsonia), Joe Pye weed (Eupatorium fistulosum), oriental poppy (Papaver orientale), raspberry (Rubus biflorus), and red twig and yellow twig dogwood (Cornus stolonifera).
AFTER CARE OF ROOTED CUTTINGS
The rooting time for cuttings varies greatly depending on the species, the time of year, and the growing conditions. Leaf cuttings may root in about 3 weeks, whereas woody cuttings may take up to 5 months to root. To test for roots, wait until you see new growth on the cutting. Give the cutting a gentle tug. If it doesn’t give, then you know it has developed roots, but don’t be in a rush to transplant. Give the cutting a chance to develop a more robust root system first. Before transplanting, make sure the plant has had a chance to harden off or acclimate to the growing conditions in the garden. Transplant when you see roots starting to grow from the drain holes of the container. A week or so later, start fertilizing with a liquid fertilizer. Because plants propagated from hardwood cuttings may be slow to develop roots, they may benefit from being left in the pot for a season or two before being transplanted to their permanent sites.
ONE LAST THING TO THINK ABOUT: TRADEMARK VIOLATIONS
As you contemplate propagating some of your plants, keep in mind that many commercially sold plants are patented. Depending on the plant, this means taking cuttings for propagation purposes may be a patent violation. When you purchase a plant, always check the label for patent information. A plant protected by a patent will bear a trademark (™) or patent number. Often you will see a label that reads PPAF (Plant Patent Applied For). Also, look for warnings, such as “propagation strictly prohibited” or “asexual propagation prohibited.”
Vegetative propagation methods have been practiced for thousands of years among many cultures worldwide. The techniques are fairly simple and can be easily mastered with a little practice and experimentation. Once you see how easy it is to propagate plants vegetatively, you’ll wonder why you haven’t tried this sooner. Don’t worry if some of your efforts fail. Successful propagation depends on a lot of variables. Even the experts don’t always have a 100% success rate. Just root more cuttings than you need, and if you have a high success rate, share some of the surplus with friends. They’ll be delighted to receive free plants from you.
Encyclopedia of Gardening Techniques, The American Horticultural Society (Beazley, Mitchell, 2013)
Plant Parenting (Halleck, Leslie F., 2019)
Plant Propagation, The American Horticultural Society (Editor-in-chief Alan Toogood, 1999)
“Propagating Plants by Cuttings,” Missouri Botanical Garden Visual-guides/propagating-plants-by-cuttings
“Propagation by Cuttings, Layering, and Division, VCE Publication 426-002
“New Plants from Cuttings,” Purdue University Cooperative Extension Service, Publication HO-37-W.
North Carolina Extension Gardener Handbook (ncsu.edu/extension-gardener-handbook/13-propagation)