Imagine losing your roots and growing new ones in 7-10 days! This is one of the common miracles occurring in the plant kingdom. It’s called vegetative reproduction, and you can use it to your advantage when you want to create more of a particularly superior plant, or when you want to expand production without spending a lot of money on new plants.

In this article, I’ll tell you how to take cuttings and propagate many kinds of perennials, shrubs and trees that are useful to cut flower growers.

Some plants are definitely more eager to grow roots than others. A forsythia branch on the ground will easily send roots down into the earth. This section, when separated from the mother plant, is identical to it. It is called a clone.

Rhizomes, runners, bulbs and corms create natural clones. Potatoes and sweet potatoes are all clones. Fruit trees are all vegetatively propagated by grafting. Mums, poinsettias, many shrubs and trees are all vegetatively propagated. There is a long history of natural aFlnd man-made cloning.

With vegetative propagation, all the plants you create will be identical. They will grow at the same rate and all will be ready for harvest at the same time. The only variation will be caused by environmental differences. One disadvantage of cloning is that all the plants will be susceptible to the same diseases in the same degree.

Propagation on a small scale can be very simple. Salvia leucantha is a good example. We keep the Salvia mother plant outside all summer, in a container or in the ground. In fall, we bring the plant into the greenhouse. After flowering, we cut it back hard, usually to about two inches. This makes it easier to manage all winter and it promotes lots of shoot growth which provides lots of cutting material. We fertilize with a low-disage fertilizer and let the plant grow until late March or April when cuttings are needed.

I prepare containers to put the cuttings into. I use 2 1/2” pots that are about 4” deep. There are 32 in a flat. Fifty cell trays also work well. You don’t want to use something too much larger because it is then too easy to waterlog your media. The cutting is not using much water until it creates roots, so a smaller pot is safer. The cutting also needs air present in the media. For less vigorous crops, 1204’s or 1206’s also work well. I use a regular peat-based potting mix to root the cuttings in. Although it is probably not necessary for herbaceous cuttings, I use a rooting hormone.

I begin from the top of the Salvia and work down. Since days are short, the plant is flowering again. I remove the flowers. As you work down the stem, cut two nodes off at a time. A node is the point on the stem that the leaves grow out of. You can take lots of cuttings at a time and store them in a plastic bag or you can take one cutting and stick it as you go. For each cutting, remove the leaves from the bottom node; I just tear them off. Then cut about one third off the ends of the top two leaves. Roots will grow from the bottom node, and the removal of part of the top leaves helps reduce transpiration loss. Dip the stem in rooting compound, either powder or liquid. Stick it immediately in the moist potting mix, being sure the bottom node is well into the potting media. When a whole tray is done, I water it and move on to the next.
Since we do not have a mist system for cuttings, we wave the hose over them whenever we pass by, usually 3-5 times per day and sometimes more. We keep them in an area of the greenhouse that is bright, but not the brightest. The cuttings do look bedraggled for a day or two, and then they perk up. This is a busy time of the year for us, so we don’t worry or fret about the cuttings and 98% of them root.

An overview of vegetative stem propagation in general will give you an ability to propagate with confidence. Vegetative propagation is possible because most plants can produce adventitious roots. These are roots made from cells that were something else in the plant (besides roots). When you take a cutting, you wound the plant. The injured cells die, the wound is sealed, a callus is formed, and some of the cells in this region dedifferentiate; that is, they return to a more primitive state and become a new growing point, which becomes a new adventitious root. This ability is stronger in some cells than others and stronger in some plant parts and locations than others. Juvenile sections of the plant are more capable of dedifferentiation than mature sections.

The juvenility or maturity of parts of a plant is not related to the actual age of the plant. Tissues laid down first remain the most juvenile. So the base of a tree or shrub is the most juvenile although it is the oldest. The flowering sections of a tree or shrub are the most mature, but they are usually the youngest. Juvenile sections usually roots more readily than mature sections of the plant. This juvenility of the lower trunk is why trees sprout so readily when they are cut off.

For a cutting to form roots, it must also contain leaves, buds or a growing tip. These structures produce IAA (Indole-3-acetic acid) which is essential for rooting. IAA is an auxin which is a natural plant hormone. Some plants have enough natural auxin to root easily with no additional auxin needed, some root easily with additional auxin applied and some plants will not make adventitious roots no matter what! Just stubborn, I guess. Synthetic auxins, also known as rooting hormones, are usually used because they are more effective. IBA (Indolebutyric acid) and NAA (naphthaleneacitic acid) are the most effective. Used together they produce more roots and a higher percentage of rooting. Before modern chemists isolated and identified auxins, early plant propagators would tie a wheat kernel in the split stem of the stem cutting to enhance rooting. As the wheat germinated, it released auxins, which helped promote root development. Recent research also indicated the mycorrhizae can enhance root initiation and growth also.
Make sure your mother plant is healthy and well nourished. Good light (usually full sun) ensures that the cuttings will have a good carbohydrate level, which will help the cutting survive until roots are formed. A good carbohydrate level also helps make good top growth after root development. Tip cuttings are often lowest in stored carbohydrates, so more basal cuttings will often root better.

If your chosen plant flowers in response to day length, you will want to root during the vegetative phase of growth. For example, bloom time of mums is triggered by short days, so you want to root during the long days when vegetative growth occurs. However, in real life, a mum will probably root anytime. Removal of flower buds will hasten rooting, though. For difficult-to-root species you may need to experiment to find the best time to take cuttings.

Cuttings can be taken from herbaceous plants and from woody plants. Herbaceous cuttings would include perennial or annual plants such as salvia, chrysanthemums, agastache… These cuttings are usually 3-5 inches long. Auxins are not usually necessary, but their use results in a larger root system.

Woody cuttings can be softwood or hardwood cuttings. Softwood cuttings are taken of new spring growth. There is usually a 2-8 week window of opportunity here, although some plants will have growth spurts throughout the summer. You want soft flexible shoots, just after a growth spurt, but they should be mature enough to break if bent sharply. Select shoots in full sun; do not select weak interior shoots. The best shoots usually come from side branches. If there are not many side shoots, you can cut the plant back (previous to the growth spurt) to force it to produce more. These cuttings should be 3-5 inches long with two or more nodes. Lilac, Forsythia, Magnolia, Spiraea, maple and crabapple root easily from softwood cuttings. These cuttings need the most care because they have leaves and they usually take longer to root than herbaceous cuttings. You must keep them alive until roots form. This involves keeping the cuttings from drying out at all times; from the time you cut them off the mother plant until they root. Commercial propagators have mist systems which can be set for so many seconds every couple of minutes. Mist reduces evaporation from the cutting by reducing transpiration and leaf temperature through evaporative cooling. If you use mist, you may also need to use bottom heat, since mist will also reduce media temperature. Although mist is very helpful to the plant, you can have success by just providing a humid environment to help prevent transpiration. Bottom heat for the 2-5 weeks it takes roots to form is also helpful. Auxin application of 500-1250 ppm of IBA or NAA also helps.

Hardwood cuttings are taken from mature dormant wood after leaf drop from fall to early spring. Forsythia, Wisteria, willow, poplar, crape myrtle, Spiraea, rose, grape and pear can be propagated by hardwood cuttings. It is helpful to put these in the greenhouse for about a month with bottom heat to get roots forming, and then plant them outside or in a cold frame. Treatment with 2500-5000 ppm IBA or NAA is helpful.

For all cuttings, orientation is important. You can’t stick a cutting upside down and expect it to grow. Even cut off the plant, the cutting knows up from down. Many people make a straight cut on the bottom of the cutting and a slanted cut on the top. You can tell just by looking at the buds though. A bud always comes out on the top side of the node. I often leave more stem below the bottom node when taking cuttings. This helps the cutting stand up better. I cut very close to the top node though because everything above it will die anyway. Just a matter of sanitation really, since less dead plant material means fewer entry points for disease organisms. Speaking of sanitation, make sure your tools are clean; dip them frequently in sodium hypochlorite solution. Also make sure your shears are sharp so you can cut instead of tear. They are called cuttings after all.

Woody cuttings are pickier about rooting media than herbaceous cuttings. The rooting medium must be stiff enough to hold the cutting upright. It must provide moisture and permit air exchange. It must be dark, so roots will grow. There are many choices: peat/perlite, peat/perlite/vermiculite, sand, rockwool, oasis cubes or any premixed rooting media. A small amount of fertilizer will help the roots grow after they have formed. No fertilizer is necessary until root have formed.

Some plants cannot be legally propagated for any purpose without a license. These plants are patented. Tim Wood, from Spring Meadow Nursery, Inc. says a plants tag or description in a catalog should tell you whether the plant is patented or trademarked. There is a web site you can check: uspto.gov. A patent lasts for 20 years and means propagation is prohibited without a license. You pay a royalty fee for each plant when you buy it. Part of the money goes to the breeder, to encourage the development of more new plants.
A trademark is different. Tim says you can’t trademark a cultivar name, so new names are invented to help sell a plant and it is the name that is trademarked. It is legal to take cuttings of plants that are trademarked but not patented but you cannot use the trademarked name when you sell the plant or any part of the plant.
Most perennials can be propagated in summer after they have flowered. There are many new books on propagating anything from A-Z. So you might want one of them. For woody information I use Manual of Woody Landscape Plants by Michael A Dirr. He tells when to take cuttings and what method to use. His descriptions of plants are always entertaining!

This may all sound difficult, but give it a try. One year my mother cut the dry heads off her hydrangea and stuck them in a pot on her patio for decoration. By spring, they all had roots!

Here is a list of plants easy to propagate by stem cuttings:

Ageratum
Antirrhinum
Buddleia
Callicarpa
Centranthus
Chelone
Chrysanthemum
Cornus
Coleus
Dahlia
Delphinium
Dianthus
Echinops
Forsythia
Helenium
Helianthus
Hydrangea
Iberis
Ilex verticillata
Lysimachia
Monarda
Penstemon
Perovskia
Petunia
Salix
Salvia
Sedum
Solidago
Solidaster
Syringa
Veronica
Veronicastrum

Jozie Schimke is the co-owner of Earth Flowers, a garden design and installation business, and a cut flower grower. She is also the circulation manager of Growing for Market.