Gardeners like nothing better than to share their plants with their friends or increase some of their favorite plants, and fall and spring are the best seasons for propagating plants. There are several excellent ways to accomplish this, such as placing some cuttings in a glass of water (which method results in tender roots making them harder to transplant and will not work on many plants.) Other ways to propagate most plants, such as dividing, layering and mounding, are far more successful. By propagating your own, you can save quite a sum of money, especially if you have purchased some that are quite expensive.

The purpose of propagation of plants is to increase plants that are identical to the parent plant, whereas if grown from seed, there can be variations. Also, growing plants from seed requires more time to develop mature plants. To propagate plants is quite simple, inexpensive, and requires but little labor and equipment. Briefly, here are some methods to increase your favorite shrubs, bushes, vines and perennials:

Stem cuttings: Three types of stem cuttings are softwood, semi-hardwood and hardwood. Softwood cuttings are those taken from new growth of the current season, and are used for deciduous shrubs, such as forsythia and lilac They generally are the easiest to root, and don't require special handling. The best months to take softwood cuttings of shrubs are June and July, although some may be taken in August and September.

Semi-hardwood cuttings: These cuttings are taken during the summer, but are made from current season's growth that has partially matured and is becoming woody. Holly, euonymus and azaleas are good candidates for this type cuttings.

Hardwood cuttings: Hardwood cuttings can be taken from both deciduous plants (plants that shed leaves in winter) and evergreens during late fall and early winter when plants have become dormant. Privet, willow, poplar, honeysuckle, grape, spirea, as well as junipers (cedar) and yews can be propagated in this manner. Cuttings are taken from terminal shoots of the previous season's growth and a small portion of year old wood at the base will root best.

For cuttings of any type, it is very important to have the proper rooting medium, light, and humidity. The rooting medium should be sterile to prevent disease. Several different products are good to use, such as coarse sand, vermiculite, perlite and Canadian peat, usually mixed 50-50. Good combinations are: vermiculite and sand, perlite and peat. Do not use regular garden soil because of probability of disease.

Length of cutting may vary from 4 to 24 inches, although most are made from 6 to 10 inches long, with diameter from 1/4 inch to 1 inch, depending on plant being propagated. As little time as possible should lapse from time cuttings are made until the time they are inserted into the rooting medium. If you are taking cuttings from plants away from where you plan to root them, enclose them in plastic bags into which you have put dampened paper towels and place in a cool place in order to keep the cuttings as fresh as possible.

Containers to hold your cuttings can vary, depending upon how many you are trying to propagate. Special beds prepared in a shady area of the yard, or covered with shade cloth in an area receiving sun, are best for multiple cuttings. However, 4, 6 and 8-inch flowerpots are excellent for smaller numbers of cuttings.

To prepare your cuttings, remove all but two to four leaves at the tip of the cutting, dip end in a rooting hormone and shake off excess. Using a pencil, make hole in rooting medium that has been thoroughly dampened, insert cutting, firming the rooting medium around each. If you are doing a number of cuttings in a prepared bed outdoors, be sure the keep the cuttings evenly moist, but not wet. If you are using flowerpots, a good way to keep the cuttings moist is to insert the pots in clear plastic bags, using a rubber band around the bottom to secure the bag. To keep any leaves from touching the bag, carefully lift a side of the bag and gently blow into it so that it will create a balloon-like enclosure. You may have to do this periodically if you find that your miniature greenhouse has collapsed.

My favorite method of starting some of my herbs, roses and other plants is to use either 4-inch or 6-inch plastic pots. For the 4-inch pots cut the bottoms out of 2-liter plastic soda bottles, remove the paper wrapping, then simply place the bottle into the 4-inch pot into which you have inserted the cutting. Be sure to remove the cap from the bottle. If using 6-inch pots, plastic juice containers will work. These miniature greenhouses make excellent places for rooting because they give the cuttings high humidity, which helps them root. Check occasionally to be sure your rooting medium does not get too dry, but usually it is not necessary to add more water.

The time to form roots differs greatly between plants. Some, such as impatiens, basil, coleus and others will root very quickly, while most woody softwood cuttings take longer, and hardwood cuttings can take even longer. After cuttings have produced some roots at least 1 inch long, they are ready to be transplanted into their growing medium. A good way to tell if cuttings are rooted is to tug gently on the stem, and if it resists being pulled out, it usually is ready to transplant.

If you are only rooting a few cuttings, pot them in individual containers in a good growing medium that has been thoroughly moistened and place in a shaded location until they have recovered from any shock of transplanting. If rooting perennials in the fall, simply bury the pots up to the rim in a protected shady area and mulch around them. In the spring, they can then be lifted from their pots and planted in a permanent location.

Besides propagating plants with cuttings, there are other ways to form new plants, especially when other methods are impractical or ineffective.

One of the best ways to get new plants is simply dividing them. Many plants can be increased in this manner, including peonies, iris, daylilies, hostas and many other herbs and perennials that form clusters. Dig the whole plant out of the ground, hose off the dirt, and using a spading fork, shovel or heavy duty knife, divide the cluster into two or more sections, making sure there are growing crowns on each piece, then replant each or give any surplus to your gardening friends.

Another good way to propagate new plants is called layering, and this is the easiest way. It is successful with more species of trees and shrubs than any other method of vegetative propagation. Because an entire branch of the parent plant is often needed to form a single new plant, the method is useful for propagating only a few plants from each parent. Layering is easy to perform and can be done without any special equipment.

Simple layering may be performed when a plant has a branch low enough to be pulled down to the ground and buried in the soil with the tip protruding. The best way to accomplish this is to make a slanting cut or scrape away some bark about 12 inches from the tip, bending the branch upward and burying the cut or wounded area about 3 to 4 inches deep in the soil. Fasten it down with a U-shaped wire or a stone to keep it buried. (Wire coat hangers cut and bent are good for this purpose.) If the branch is stiff, you may want to place a stake alongside and tie the branch to it. This type of layering can be done in spring or fall, and is especially good for some broadleaved evergreens, such as holly, rhododendron or magnolia. Keep the ground moist around the layer at all times and mulch with straw, leaves or sawdust. The layer may form roots during the first season, but some hard to root plants make take a couple of seasons. After the new plant is well rooted, cut it from the parent plant, but do not dig for a couple of days to give it time to recover from any possible shock, then plant in its new location.

Another method of layering called mound layering, is also an easy way to propagate new plants. All that is necessary is to mound up some soil around the base of the plant, so that some nodes on the stems are buried, and roots will eventually form. Usually autumn is a good time to try this method, and by the following spring the rooted stems can be cut away from the parent plant and planted separately.

Compound layering is done on vining plants, such as honeysuckle, grape, clematis or wisteria. The procedure is the same as simple layering, except that the whole branch with a number of nodes is buried, with the exception of the tip. Wounds are made at each node to be buried, and after rooting, the branch is cut into each rooted segment for transplanting.

Many plants will increase on their own because they send out runners, either on top of the ground or just beneath the soil, which then root at each node and can be cut away and planted. Mints and ajuga are plants in this category.