Plant Propagation

We categorize plant propagation into two groups, asexual propagation (the many ways of reproducing without seeds) and sexual propagation (via seeds).

Asexual Reproduction

Asexual propagation is often the tool of choice when a food crop's plants can't self-fertilize. For example, apple trees aren't fertile unless pollen from one tree mates with the eggs on another tree.

Unfortunately, this means that the seeds in every apple on a tree could produce an apple with a different look and/or taste.

To avoid this problem, orchardists use asexual reproduction techniques to have every apple tree produce the same fruit.

Asexual Propagation Methods

There are many different ways to expand your plant collection without growing seed. These include:

• Cuttings, removing a piece from the parent plant and giving it the growing medium and nutrients it needs to regrow the missing tissue.

• Root Cuttings, which are parts of new root growth, where the most vitality is. The best time to take these cuttings is during the dormant season (autumn) when the roots have built up a large supply of carbohydrates. However, if you need them, you can also take them during the growing season.

  Take cuttings 1-4 inches (2.5-10 cm) long from roots that are approximately 1/4 to 1/2 inch (.6 to 1.2 cm) in diameter.

• Leaf Cuttings, which are healthy leaves cut from the plant. A new plant grows at the base of the old leaf. You can propagate succulent plants, such as sedum, jade, and peperomia by leaf cuttings.

  With a disinfected knife, cut the leaf close to the stem. Cut off about 25% of the leaf. Dip it into a rooting hormone solution, then insert it into a rooting medium so that about 1/3 of the leaf is below the surface.

• Stem Cuttings, the most common method used to produce houseplants.

  Select some vigorous growth that has no flower buds on it. You don't want any of the plant energies to go toward seed production when it should be focused on tissue growth. A visual exam should also show it to be free of disease and insects.

  Cut each stem to 2-4 inches (5-10 cm) long, with 2-3 leaves attached. Dip in the rooting medium and then insert into the rooting medium.

• Softwood, Semi-Hardwood, and Hardwood Cuttings are taken from woody plants such as trees and shrubs. Softwood cuttings are the non-woody first year branches. Flowing shrubs are usually propagated by softwood cuttings.

  Once the tissue becomes woody and the plant is dormant, hardwood cuttings can be taken. Cuttings can be taken from late fall, before (semi-hardwood cuttings) or after a killing frost until late winter (hardwood cuttings).

  The same rooting formula/rooting medium process applies, but you'll need a larger area of medium to accommodate the larger cuttings. See this article on evergreen and deciduous plant propagation for details.

• Division is a popular plant propagation method used with larger plants. A crown, rootball or clump of suckers is cut into two or more segments, depending on the size of the plant and its root system.

  After you've dug around the plant, use a sharp knife or a shovel to cut through the crown or rootball. Each segment needs at least one bud and some root tips. Plant each segment, which will eventually grow into a clone of the original.

• Layering, done with some plants that send out shoots. As the shoots grow, they develop their own roots. Layering is a good propagation choice when just a few plants are needed.

  Cut the stem away from the mother plant after the roots are big enough to sustain the new plant on its own.

• Bulbs and Corms, which grow at the base of the plant. These bulblets or offsets usually take 2-3 years to develop into plants that flower.

  Gently dig around the base of the plant and remove the small bulbs. Plant where you'd like the new plant to appear.

• Tubers and Rhizomes, which are underground growths that have the ability to reproduce. The potato is an example of a tuber, and turf grass is an example of a rhizome.

  Each tuber must have at least one eye or bud, which will then use the energy in the tuber to grow into a new plant, which will then produce more tubers. You can cut many tubers into sections, as long as each one has at least one eye.

  Rhizomes look like roots, but each section of a rhizome has a bud or eye. You can create several new plants from a short piece of rhizome, as long as each one you plant has a bud.

• Grafting, or the attaching of a piece from one plant to a piece from another plant. This is how most orchardists reproduce most fruit trees. This is especially useful when creating dwarf varieties of fruit trees.

  For example, you can create a small version of your favorite large apple tree by cutting off a small branch that has a bud on it (this is called the scion). It needs to be about the same diameter as the rootstock that you purchased (it's the rootstock that determines the size of the tree—you can buy various types of stock depending on what you want to grow).

  With a disinfected cutting tool, cut the branch and the rootstock on a 45 degree angle so that when placed together, they look like a new, small tree. Wrap them with a thin strip of clean plastic wrap and place in the ground where you want your new tree to grow.

  Natural grafting occurs when two branches come into close contact over several years. Ivy is an example.

• Bud Grafting, an easier and faster method of grafting, since the two plant parts don't need to be aligned. A slit is cut into the bark of the tree, and a bud is placed into it. The incision is sealed to prevent disease organisms from entering.

  This is one way to have different fruit grow on the same tree. For example, I once saw an apple tree that grew apples on one side, and pears on the other.

• Micropropagation, or Tissue Culture, usually done in the laboratory. Small portions of tissue, sometimes even single cells, are used to create copies of the parent plant.

• Vegetative Propagation, used by poplars and other plants. Once planted and established, poplars are almost impossible to remove from a property, since there's never just the trees. More like a colony, there are always long underground stems producing new trees, often many yards away from the original planting.

Sexual Reproduction

Sexual propagation of plants means the exchange of genetic material between two parents to produce a new generation. Sexual propagation gives these advantages:

• It's usually the only method of producing new varieties or cultivars.
• It's often the cheapest, quickest and easiest method of producing large numbers of plants.
• It can help avoid certain diseases.
• It may be the only way to propagate some species.

Sexual Plant Propagation Methods

• Spores, used by ferns to reproduce. The underside of each frond (fern leaf) develops clusters of spores, which fall to the ground or are carried by wind to a new location, where a new fern develops.

• Seeds, the most common method of producing new plants. Annual and biennial vegetables and flowers are usually grown from seed. Perennials grown from seed may take more than one season to flower.

See this article on using seeds to grow plants.

This article discusses some uncommon or unusual plant propagation.

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