Propagating with Layering
Layering is another method of asexual or vegetative propagation, where a stem still attached to a parent plant forms roots when that stem maintains contact with a rooting medium. Then, the rooted stem is cut from the parent plant, forming a new plant. This propagation method is very successful because it avoids water stress and carbohydrate shortage issues often encountered with propagation through cuttings.
Tip layering is accomplished by digging a hole 3- to 4-inches deep, inserting the shoot tip into the hole, and covering it up with soil. The tip of the stem will initially grow down into the soil but will then turn sharply upward. Roots will then form at the buried bend in the stem. The stem can be severed on the parent plant side of the newly formed roots creating a new plant. The new roots and the stem tip that emerged from the soil where the tip was buried can then be planted in early spring or fall. This method can be used for propagating grapes, muscadines, and some other trailing fruits.
Simple layering is accomplished by bending a long stem to the ground and covering part of it with soil while leaving 6- to 12-inches of the stem’s tip exposed. The tip should be bent so that is vertically oriented which may require that you stake it. Roots should develop at the buried bend in the stem, but you can often further induce rooting by wounding the lower side of the portion of the stem you plan to bury or by twisting the portion of the stem you plant to bury in order to loosen its bark. This method works for propagating plants like honeysuckle, rhododendrons, and forsythia.
Compound or Serpentine Layering
Compound layering (also known as serpentine layering) is accomplished by taking a long stem of a plant with flexible stems and covering multiple sections of the stem with soil like in simple layering, creating alternating sections of buried stem and exposed stems. It is suggested that you wound the lower side of the stem at each place you plan to bury it. This method works for propagating plants like pothos and heart-leaf philodendron.
Mound or Stool Layering
Mound layering (also know as stool layering) is accomplished by cutting back the stems of the plant to about 1 inch above the ground during its dormant season and completely covering the remaining shortened stems with soil. In spring, the shoots will develop from dormant buds on the buried stems. Roots will also develop at the base of the new shoots. When the roots develop at the base of the new shoots, the old, buried stems can be severed just below the new roots and shoots creating new plants that can then be planted elsewhere. This method is often used to propagate apple, pear, and quince trees.
Air layering is a method for inducing plant stems to produce roots above the ground. It is accomplished by first selecting a vigorously growing stem or branch. You then make a 1- to 2-inch cut along the stem about ¼ to ½ way through the stem about 12- to 15- from the tip. Insert a toothpick into the cut to hold it open while you apply rooting hormone to the surfaces inside the cut. If the stem is thick, you may need to make cuts on both sides of the stem and apply rooting hormone to both cuts. Once the stems have been prepared, pack a handful or two of moist sphagnum peat moss around the portion of the stem where it was cut and hold it in place around the stem with a plastic bag or aluminum foil. A root ball of white roots should develop inside the plastic or aluminum foil. Once this occurs, the stem or branch can be severed just below the new root ball, and the resulting new plant’s root ball can be carefully unwrapped allowing it to be potted in an appropriate planting medium.
Stolons and Runners
A stolon is a stem that run horizontally across or just under the ground, which produces shoots and roots at its nodes, creating new plantlets. A runner is a stolon that originates from a leaf axil at the crown of the plant and grows across the ground or hangs downward from a hanging plant, creating new plantlets at its nodes. New plants can be created by severing the new plantlets from the stolon or runner of the parent plant. If the new plantlets have not created roots prior to be severed from the parent plant, then they can be placed in a rooting medium once they are detached. Spider plants and strawberries can be propagated using this method.
An offset is a small daughter plant that has been naturally produced by the parent plant and as such are genetically identical to the parent plant. This occurs often in plants with rosetted stems, cacti, succulents, and bromeliads. The offset (daughter plant) can be severed from the parent plant to create a new plant. If roots have not already developed for the shoots, then the unrooted shoot can be placed in a rooting medium and rooted.
Separation is used to propagate plants that produce bulbs and corms.
Separation of Bulbs
A bulb is a short stem surrounded by fleshy leaves or leaf bases called scales that are used to store food during dormant periods. When you plant bulbs in a garden, they multiply over time by forming new bulbs next to each original bulb. Once every 3 to 5 years, you should dig up the clumps of bulbs after the leaves have died, gently separate them, and replant them immediately so that their roots can develop. Tulips are an example of a plant that can be propagated this way.
Separation of Corms
A corm is a short, swollen, underground plant stem used to store food to survive winter or other adverse conditions like summer heat and drought. Each year in spring, a new corm develops above the old one, and new roots sprout between the old and new corms. The old corm and its roots die. Cormels, which are tiny corms, also develop between the old and new corms. Each year you can dig up the corm and gently separate the old corm, new corm, and cormels from one another. The old, dead corm can be discarded, while the new corm and cormels can be replanted. This is how gladiolus and crocus are propagated.
Division can be used to propagate plants with more than one rooted crown. The multiple crowns are divided and planted separately. If the stems are not joined, you can simply pull the plants apart. However, if the crowns are connected by horizontal stems, then the connecting stem should be cut with a sharp instrument to minimize injury. The crowns of some outdoor plants propagated using this method may need to be dusted with a fungicide before planting.