Here's a beginner's guide to plant propagation

May 16, 2011
Learning to propagate plants—to make new plants from existing ones in your home and garden—is one of the most exciting and rewarding aspects of gardening. Many of the methods are easy, and you don’t need fancy or expensive tools. Propagation is cheaper than buying large numbers of plants, so with a little time and effort you can fill your garden quickly at minimal cost. Propagating new plants will keep your house and garden full of vigorous specimens, and you’ll probably have plenty to give away, too!
You can reproduce most plants by several methods. There are two major types of propagation: sexual and asexual. Sexual propagation involves seeds, which are produced by the fusion of male and female reproductive cells. Asexual propagation methods use the vegetative parts of a plant: roots, stems, buds, and leaves. Division, cuttings, layering, budding, and grafting are all asexual methods. Spores (produced by ferns and mosses) may look like seeds, but they are technically asexual structures, because they have a specialized way of forming new plants. 
Select a technique by considering the plant you are working with, the materials you have, the season, and the amount of time you are willing to wait for a new plant.
Growing from seed is an inexpensive way to produce large numbers of plants. Annuals, biennials, and vegetables are almost always reproduced by seed. You can also grow perennials, shrubs, and trees from seed, although the seedlings they produce may not resemble the parent plants. Raising seeds requires few materials: a container, a growing medium, and seeds. The time to sow seeds depends on the type of plant. For most garden plants, you can sow seeds indoors in late winter or outdoors in spring. Tree, shrub, and many perennial seeds may need a cold period or other treatment before they will germinate. Depending on the type of plant, it could take anywhere from weeks to years to get a garden-sized specimen. For complete information on growing plants from seeds, see the Seed Starting and Seed Saving entry. 
Spores are the reproductive structures of ferns and mosses. To produce new plants, sow these dustlike “seeds” on a sterile medium and cover them to maintain humidity and prevent contamination. Clear plastic shoe boxes or cups are ideal containers for propagation. You can collect spores from your own ferns or buy them from specialty catalogs. You can sow spores whenever they are available. The new plants will be ready for the garden after a period of months or years. 
Division is an easy way to produce more plants with almost 100 percent success. This method involves digging up an established plant and separating it into several pieces. Division is used for bulbs and mat-, clump-, or crown-forming plants, including ferns, bamboos, bugleweed, daylilies, and hostas. Single-stemmed plants like trees cannot be divided. 
All you’ll need for division is a tool to dig up the plant, and your hands or a sharp implement to separate the pieces. You can divide most plants in either spring or fall. Division produces full-sized plants that can be placed directly in the garden. 
Cuttings are pieces of leaves, stems, and/or roots that are separated from a parent plant. When placed in the proper conditions, these pieces form new roots and shoots. Stem cuttings are used for a wide range of plants, including geraniums, pachysandra, and coleus. Use root cuttings for perennials such as Oriental poppies (Papaver orientale) or globe thistles (Echinops spp.) and some trees, including goldenrain tree (Koelreuteria paniculata). You can also try leaf petiole cuttings, used for African violets and peperomias, and leaf pieces, used for such plants as gloxinias and snake plant (Sansevieria spp.). 
The materials you’ll need depend on the plant and the method you are using. Leaf petiole cuttings of African violets will root in a simple glass of water. You can stick stem and root cuttings in a pot or flat of regular potting soil. A plastic bag or other clear cover will help to maintain high humidity around the cuttings. More complicated structures, such as cold frames and mist boxes, are good for hard-to-root shrub and tree cuttings. Plants reproduced by cuttings can be ready for the garden in a matter of weeks or months. 
Layering is a way to get stems to root while they are still attached to the parent plant. Some plants produce layers naturally. Strawberries form rooted plantlets on runners; raspberries produce new plants where the stem tips touch the ground. The technique of simple layering involves bending a low-growing stem to ground level and burying a few inches of the stem behind the tip. Simple layering is an easy way to reproduce such plants as camellias, forsythias, and magnolias. To air layer, you shallowly wound a stem a few inches below the tip to stimulate root production, and then wrap moist sphagnum moss around the stem. Covering the moss with a thin sheet of plastic holds in moisture and secures the moss to the stem. Weeping fig trees (Ficus benjamina), corn plants (Dracaena fragrans), and witch hazels (Hamamelis spp.) are all good candidates for air layering. 
You don’t need much equipment to try these techniques. A trowel (for digging the trench) is sufficient for simple layering. For air layering, you’ll need sphagnum moss, waterproof tape, a piece of thin plastic, and a knife. Early spring is the best time for simple layering. For outdoor plants, you can set up air layers in spring or late summer. Indoor air layers can be started anytime. It will probably take several months to a year to get a new well-rooted plant. For more information, see the Layering entry.
Grafting is a more advanced propagation technique. It involves joining a stem piece of one plant (the scion) to the root system of another plant (the rootstock) in such a way that the parts unite and continue to grow. You can reproduce many types of trees by grafting, including pines (Pinus spp.) and rhododendrons, and even some herbaceous plants, such as cacti. Grafting has several advantages over other propagation methods. It allows you to propagate plants that are difficult to raise from seeds or cuttings. Through grafting, you can produce a plant adapted to your particular needs. Some rootstocks have a dwarfing effect, while others encourage vigorous top growth. They can also provide tolerance to soilborne insects and diseases, or to less-than-perfect soil conditions
The most important grafting tool is a sharp knife. You may also need string or tape (to keep the graft pieces together) and grafting wax (to prevent water loss and avoid contamination). You’ll have to have suitable rootstocks, too. You can raise your own from seeds or cuttings, or buy them from a specialty catalog or nursery. Spring is the most common time for grafting. Herbaceous plants will join successfully in a few weeks; woody plant grafts usually take a month or two to unite firmly and begin growing. See the Grafting entry for more details on this technique.
Budding is a particular type of grafting. In this method, you use only a single bud from the desired plant. Budding is commonly used to propagate fruit trees as well as ornamentals, such as hybrid tea roses. For the home gardener, the advantages of budding are similar to those of grafting. In some cases, budding is more successful than grafting because it is easier to get close contact between the bud and the rootstock. Budding also allows you to propagate more plants if you have a limited amount of scion material. 
For this technique, you’ll need a sharp knife and some string or tape to secure the bud to the stem. As with grafting, compatible rootstock plants are necessary. Budding is best done in late summer or early fall. Buds inserted at this time will produce new growth the following spring.