Propagation

Flowering plants grow from seeds, but that’s not the only way to propagate new plants.

Division of Shasta daisies

Very often, you can propagate new plants from old ones by taking a piece of the parent plant and giving it a warm, moist place to grow. This works because plants have undifferentiated cells that can become any part of the plant. Given the right conditions, meristem tissue that was going to become stem or leaf can develop into roots instead. Vegetative propagation can take several forms.

Cuttings

Many houseplants are propagated by cutting off a stem and sticking it in water until roots appear. Succulents are particularly well suited to propagation by cuttings. Simply break off a leaf and stick it into some soil. Cuttings can be taken from leaves, stems, and roots and coaxed into producing new plants with varying degrees of success. Some plants root faster and more easily than others. Generally speaking, woody stems are more difficult to propagate with cuttings than soft-stemmed plants.

Division

Magnolia stem cutting has formed roots (Gmihail) CC BY-SA 3.0 rs

Many bulbs and perennial plants benefit from being divided every few years. This happens because the root system can become overcrowded. Artichokes, chrysanthemum, germander, saffron crocus, and yarrow often benefit from being divided. If you dig up one of these plants, you can pull or cut them into smaller portions and replant elsewhere. Division is normally done in autumn, unless it is an autumn-blooming plant, such as saffron crocus, in which case division is performed in spring. Autumn temperatures give plants time to recover and develop new root systems.

Layering

Strawberry runners are an example of layering. Layering is a method in which portions of a plant are bent to the ground and covered with soil while still attached to the parent plant. The parent plant provides water and nutrients needed by the daughter plant until roots emerge from the soil-covered nodes. Once the clone is established, it can be separated from the parent plant. In many cases of layering, the section of the plant touching the soil is purposely wounded to stimulate rooting. There are six types of layering: air, simple, compound, tip, and trench methods.

Layering (Pearson Scott Foresman, Public Domain)

Suckers and root sprouts

Suckers are shoots that occur at the base of a tree or shrub. Root sprouts come up from the root system, usually at a distance from the parent plant. ​Scions

Scions are young twigs cut from parent plants, usually trees, which are then grafted onto other trees. The meristem tissue found within the scion dictates what sort of blossoms and fruit will be produced. Scions are what make “fruit cocktail” trees possible. These are trees that produce a variety of fruits. You can have a single citrus tree that produces Valencia and Navel oranges, kumquats, grapefruits, and tangerines, or you can have a stone fruit tree that produces peaches, nectarines, apricots, and almonds.

Whip graft of scion (Chris Hibbard) GFDL

Suckers, also known as basal shoots, and root sprouts can be removed from mature plants and encouraged to take root elsewhere. To do this, you will need to carefully remove them from the parent plant and place them in moist soil. ​

What about GMOs?

Propagation generally refers to breeding or reproducing plants by natural processes from parent stock. How you define natural processes may alter how you feel about genetic modification. Before digging in your heels, you need to know that plants, bacteria, and fungi have been modifying genetic material [their own and that of other living things] long before we got started in the lab. For better or worse, genetic modification has a role in modern plant propagation. For one thing, without genetic modification, there would be no seedless watermelons. Seedless watermelons happen because plant breeders do two things:

1. They take the normal 22 watermelon chromosomes and double them, using a chemical process.
2. They pollinate female flowers of plants with 44 chromosomes with male plants that have 22 chromosome.

The resulting offspring have 33 chromosome and are highly unlikely to have viable seeds. That’s why you still get an occasional seed in your seedless watermelon.

Rather than going to the store to buy new plants, you can often propagate your own for free using these methods.