In gardening usage, "propagation" is a general term for the many ways of starting new plants. Familiar methods include sowing seeds, taking cuttings from stems, leaves, or roots, and ground and air layering. Division is another means of propagation. Once you learn to propagate your own plants, you'll be able to try many kinds that may not be offered at your local nursery. You can grow large numbers of plants more economically, too: for the price of a six-pack of lettuce seedlings, for example, you can buy a packet of 600 seeds.

MORE: Learn how to plant seedlings, shrubs, trees, and more in our Planting fundamentals guide