Nearly all gardeners are familiar with saving seeds and the benefits and reasons for doing so, but there are numerous reasons and benefits in learning other techniques for plant propagation. These techniques involve division, layering, stem cutting, and grafting.
For the budget-sensitive gardener, these methods allow them to reproduce new plants from friends’ plants or from their own plants and perhaps trading or selling the excess. New plants can also be gleaned from wild growing species without harming them, then transplanted into the home garden.
In some species, like trees, these techniques may be easier and faster than growing from seed. Another important reason for these types of propagation is that some plants cannot be grown from seed because the offspring will not be exactly like the parent plant. “Bartlett” pears and “Golden Delicious” apples are two examples of this.
Plant propagation techniques
Plant propagation by Division
Most perennial ornamentals, herbs, and vegetables that do not have a single stem or crown are propagated by division of the roots. Rhubarb, hostas, and mints are examples.
Division is the most commonly practiced asexual propagation method and is exactly as it sounds, that is, you simply divide the parent plant into smaller new plants.
The size of the parent plant will determine how many times it can be divided. If you do not want to reduce the size of the parent plant, usually a few divisions can be obtained from around the edges without affecting its overall size or performance.
Often, dividing an older plant will rejuvenate it, resulting in lush growth and performance the following season while keeping it in bounds.
The plant you select to divide should be healthy and dormant. Early spring is a good time to divide; however, late fall will work as well. Plants that are loosely interwoven can sometimes be pulled apart with your hands or a trowel.
Others that are tightly interwoven will require lifting the parent plant from the soil and cutting apart with a spade. Look for a natural dividing line when separating clumps. Try to keep as many of the roots intact as possible and make sure there is at least one “eye” or crown in each division.
Trim off any damaged roots and plant the division at the same depth at which it was growing. Keep new divisions well watered.
Plant propagation by Layering
Layering is another simple method of propagation. In nature, it occurs naturally when a stem, still attached to the plant, touches the soil and begins to root. This stem will become a new plant. Some plants, like raspberries and trailing blackberries, layer themselves naturally.
You can intentionally layer a plant by digging a small hole near the base of the mother plant then bending down one of the lower branches and forcing it into a “U” shape. Place the bottom of the “U” in the hole and fill the hole with soil.
It may be necessary to pin the stem in the hole with a forked branch or piece of wire bent into a “U” shape. Removing about ½-inch of bark from the part to be buried and treating it with a rooting compound will encourage root formation.
Generally plan to leave the new plant undisturbed for a year to give it time to establish an ample root system. Keep well watered. Once the new plant is rooted, it can be cut from the parent plant and transplanted elsewhere.
Serpentine layering can be done with plants that have flexible stems. Bend the branch to the ground, as for simple layering, but alternatively, bury and expose stem sections. The exposed portions should have buds for best results.
Plant propagation by Stem cuttings
Most woody and herbaceous plants can be propagated by cuttings. Cuttings involve removing a stem or branch from the mother plant and rooting it to form a new plant.
Stem cuttings should be taken from the growing tips of branches and be between three and six inches in length. Remove cuttings early in the morning or late in the evening from healthy, disease-free mother plants that are actively growing.
Use a sharp knife that has been dipped in rubbing alcohol. Make a clean, slanted cut just above a side shoot, leaf node, or growth bud. After taking the cutting, wait no more than a few minutes before you place them in the rooting medium.
Bring indoors and re-cut them for the cleanest possible cut, avoiding crushed stems and hanging strands. Remove leaves, flowers, etc., from the lower half of the stem, then dip the cut into the rooting compound.
Poke a hole in the rooting medium and insert the cutting at a depth that is one-half to one-third its length. Firm medium around the cutting. Coarse sand mixed with equal amounts of peat moss makes a good rooting medium, and the flat for the medium should be 3-4 inches deep with drainage holes.
Once all the cuttings have been inserted in the medium, water them with lukewarm water, then cover with plastic to form a tent or mini-greenhouse. Use care not to let the plastic touch the cuttings.
Place in a warm spot with good light but not direct sun and keep the medium moist but not wet. After seven to ten days, move to an area that receives partial sunshine.
If your cuttings do not root, simply try another batch. Sometimes a few days difference in the maturity of the cuttings will make a difference. It can take from one week to one month for roots to develop.
When the roots are approximately ½-inch long, transplant the cutting to a pot filled with good quality potting soil and fertilize. After the cutting is established and actively growing it can be transplanted to the garden.
Plant propagation by Root cuttings
Plants like horseradish and some of the ornamental perennials are propagated from root cuttings. Root cuttings are best taken early or late in the growing season. Although slower than stem cuttings to root and begin growing, they require less care and attention.
Dig the mother plant from the ground, then cut a two to four-inch section from one of the mother plant’s roots. Select a root that is firm and healthy with smaller feeder roots. Place the cutting in a good quality growing medium in the same position it was growing (Some plants have horizontal roots while others have vertical growing roots).
For vertical growing roots, plant the root cutting so that the top ¼-inch of it is exposed above the growing medium. For horizontal ones, simply place on the medium surface and cover with one inch of soil. Water and firm the medium on and around the cutting.
Keep the cutting moist and in a mostly shaded location until new growth appears. When growth is evident, transplant to another pot and fertilize. Gradually harden off before moving to the garden.
Plant propagation by Grafting
Grafting is a method used to join parts of different plants so they will grow as one plant. Many ornamental trees, fruit trees, and roses available from nurseries have been grafted.
This process is used to control the size of the mature plant (dwarf varieties), provide a hardier rootstock, propagate plants that do not root well, and sometimes just for the novelty of growing several different cultivars on one plant.
The part which is to be grafted to the recipient stem or root is called the scion. For successful grafting, the scion and stem or root should be compatible, and the union of the two must touch and be kept moist.
Grafting can be an entertaining hobby that requires only grafting wax, grafting tape or common twine, and a sharp knife. You can start with your own apple tree and, by grafting limbs from friends’ apple trees, grow several varieties on one. Grafting wax and tape are available from garden supply centers and can even be ordered online.
There are several different techniques used in propagation grafting. Cleft grafting is usually done to add a new cultivar to an existing one. It is done in the early spring just before plants break their dormancy.
Select a scion from one-year old shoots that is healthy with evidence of buds and approximately ½-inch in diameter. Using a sharp knife that has been dipped in alcohol, cut so that it has a double bevel in a wedge shape two inches long.
The recipient branch should also be healthy and strong with signs of pending growth. It should be two to three inches in diameter. Cut the branch perpendicularly, then make another cut vertically, two inches deep, through the previous cut.
Fashion a wedge from another branch or piece of wood and use it to hold the cut open. Use care not to tear the bark or cause any more damage than necessary. Place the scions, right side up, in the cut at the outer edge as shown and remove wedge. Cover the union with grafting wax.
This technique is used when the scion and recipient branch are of the same diameter (approximately ½ inch). It is also done in the spring, and it generally heals quicker and is stronger than cleft grafting.
Select the specimens, as above, and make a sloping cut 2½ inches long on the recipient branch as shown. Make a matching cut on the scion and place together so they interlock.
Tie firmly with twine or use grafting tape to hold in place and cover with grafting wax.
Care of grafts
For the following year, grafts will require some attention. If you used twine or tape on the graft, remove it after growth starts so that it does not harm the site. Some grafting tape, however, is designed to be left on the branch since it will stretch with growth and deteriorate in time.
Check the instructions for the particular variety of tape you used. Inspect the grafting wax every two to three weeks for the first year. If the wax has cracked, re-apply it. Keep the plant well-watered.
The plant propagation methods listed in this article should be used by any gardener that doesn’t have the budget to spend on new seedlings. Although it may take a little practice, you will soon discover that multiplying your plants by using the information provided here is rather an easy job. Happy gardening!
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