Daniel Gill, Merrill, Thomas A. | 7/28/2007 2:24:16 AM
By Dan Gill
LSU AgCenter Horticulturist
Sharing plants is one of the pleasures of gardening. When gardeners get together and a plant is complimented, it is not unusual for the admirer to be offered a "piece" to take home and root.
Getting that piece – or cutting, as its known – to survive and grow into a new plant then becomes the challenge.
A cutting is a piece of a plant that is cut off, placed into conditions where it regenerates the missing parts and grows into a new, independent plant. For most plants, the best type of cutting to use is a stem cutting, although some plants also are propagated by leaf cuttings (African violet) or root cuttings (acanthus). When a stem cutting is taken, it generally has leaves and a stem, and it must regenerate a new root system.
Stem cuttings taken from some plants root rapidly and easily, while others are more of a challenge. Success depends on taking the cuttings properly, doing it at the right time of the year and then providing them with the right conditions for rooting. Remember, the cutting must survive until the new roots form.
A common mistake made by gardeners is trying to root large cuttings in an effort to get big plants quickly. Cuttings generally should be no more than 3 inches to 6 inches long. Cuttings that length can be taken from the ends of branches (tip cuttings), or longer shoots can be cut off and sectioned into shorter cuttings.
The cut at the lower end of the cutting always should be made just below the point on a stem where a leaf or pair of leaves is attached. Take cuttings in the cool, early morning hours when plant tissue is full of water, and immediately put them in water or wrap them in a moist cloth. Keep the cuttings out of direct sunlight, and plant as soon as possible.
When preparing to plant the cutting, make sure the cutting is not too long, and trim it if necessary. Remove the leaves on the lower half of the stem. If the remaining leaves are large, such as is the case with hydrangeas, they may be cut to reduce their size by about half. But do not remove all of the leaves.
Products containing root promoting hormones are available at local nurseries and should be applied to the cuttings following label directions before planting them. These products are effective in making cuttings root faster and more reliably.
The material, or medium, you plant the cuttings into is very important. A good rooting medium must be loose enough to provide the base of the cuttings with plenty of air, but it also needs to retain enough water to keep the cuttings from drying out. It also should be free from pathogenic fungi that could cause the cuttings to rot.
A classic rooting mix is made from one part sharp builders sand to one part peat moss or shredded sphagnum moss. I often use a half-and-half mixture of vermiculite and perlite, because these materials are readily available, sterile and relatively inexpensive. Other combinations, such as sand and vermiculite, should work well. Or you can even use a light potting mix.
Whichever you choose, fill a container with the pre-moistened rooting medium. Make a hole in the rooting medium and insert the cutting one-half its length into the medium. Firm the medium around the cutting. At this stage, several cuttings can be planted fairly close together in a container, if you’d like. When all the cuttings are planted, they should be watered in.
Cuttings root more reliably in high humidity. To achieve this, place containers in old aquariums covered with glass or cover pots with wide-mouth glass jars, plastic soft drink bottles with their bottoms cut off, plastic bags or other materials that are clear. (Cuttings need light.) If you use something like plastic bags, support the plastic off of the cuttings with small sticks. (Pencils or chopsticks work well.)
Place the cuttings outside in total shade or inside in a bright window indoors that does not receive direct sunlight. Water often enough to keep the rooting medium moist but not soggy.
The time required for rooting varies depending on the type of plant. Three to six weeks is typical.
Check the cuttings periodically by gently pulling on them. When you feel resistance, rooting is under way. Check the root length by gently lifting a cutting from the medium about a week after you feel resistance. Rooted cuttings are ready to plant into individual pots when the roots are about an inch long.
Plant rooted cuttings into small individual pots of potting soil. Keep the newly rooted cuttings in the shade for about a week. Then gradually move them into the type of light the plant prefers. At this stage, you may fertilize occasionally with a soluble fertilizer.
Many shrubs can be propagated by cuttings taken now. Just remember that woody plants require patience when grown from cuttings. It may be two years or more before the plants are large enough to plant in the landscape.
Herbaceous (non woody plants, such as begonias, impatiens, coleus, many hardy perennials and many houseplants), root easily and quickly from stem cuttings taken anytime they are in active growth.
Be prepared for some failures when rooting cuttings, but do consider giving it a try. The satisfaction of propagating your own plants is hard to beat.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.