How to take cuttings
Select cuttings from vigorous, healthy wood, preferably from the upper part of the plant. Avoid excessively vigorous shoots, as well as weak, spindly growth.
Take softwood and semi-hardwood cuttings during cool portions of the day. Cuttings should be 10 to 15 centimetres long. For best results, make a slanting cut slightly below a node using a sharp, clean knife. Immediately place cuttings in a plastic bag to avoid excessive wilting.
Remove leaves from the lower half of softwood and semi-hardwood cuttings (Figure 1). Dip the base of the cuttings in a rooting hormone for faster and better rooting. Rooting stimulants are generally available in most garden supply stores. Use as directed.
Trim cuttings and remove leaves from lower half of each cutting.
The medium used for rooting cuttings must be clean and sterile. Diseases are a frequent cause of poor rooting. They may come from containers, tools, workbench or rooting media that have not been sterilized.
The rooting medium should not contain fertilizer. Begin fertilizing after cuttings are rooted and have been transplanted to a growing medium.
Clean, coarse, construction-grade sand may be used for rooting cuttings. Avoid very fine sand because it has poor aeration, which retards root formation. A mixture of one-half sand and one-half peat moss is a better rooting medium.
Vermiculite, a lightweight expanded mica product, is suitable for rooting cuttings. The horticultural grade (grade 2) is the best size to use, and it may be used separately or mixed with an equal volume of sand.
Perlite is another excellent propagating material. It is lightweight and provides good aeration to the cutting. Perlite gives best results if mixed with an equal volume of peat moss or vermiculite.
Compressed peat pellets that expand when water is added make a convenient propagation medium and container.
Heavy soils should not be used for rooting. They tend to pack tightly, which results in poor aeration and little or no root formation. They also must be thoroughly sterilized to prevent disease development.
Inserting the cutting
Allow as little time as possible to lapse from the time the cuttings are taken until they are inserted into the medium.
Stick each prepared cutting into the medium up to the remaining leaves. Water thoroughly to settle the medium around the base of the cutting.
Care of cuttings
Do not let the propagation medium dry out during rooting. However, avoid excessive watering, which results in poor aeration and death of new roots.
Use water with small sections of cut up willow stems soaked in it as a natural rooting hormone.
High humidity must be maintained because cuttings don’t have a root system. Low humidity allows wilting, scorch, leaf drop or death.
Enclosures help maintain high humidity. If only a few cuttings are to be rooted, use a miniature greenhouse or place individual pots in large plastic bags (Figure 2). Monitor the plastic bags for condensate, and water the medium when condensate disappears. Never place plastic-enclosed containers in direct sunlight because excessive heat will build up. For rooting large numbers of cuttings, use cold frames, hotbeds or greenhouses.
Miniature greenhouse constructed over a large flower pot for rooting a few cuttings.
Care of rooted cuttings
The time necessary to form roots differs greatly between plants. Most woody cuttings, such as forsythia, root in several weeks, but hard-to-root cuttings, such as rhododendron, may take three to four months. Check cuttings occasionally by carefully removing a few from the medium. After cuttings have produced some roots at least 1 inch long, they are ready to be transplanted into a growing medium.
The move from high humidity and moist rooting medium to low humidity and dryer soil is critical. Do it carefully. Watch these new plants closely during the first weeks after the move.
If only a few cuttings have been rooted, pot them in individual containers. Larger quantities should be placed in a well-prepared but protected bed or cold frame outdoors where they can be given special care for two growing seasons.
Some plants such as azaleas and rhododendrons require special acid soil, but for most plants a mixture of equal parts good topsoil, sand and peat moss makes a good growing medium. Add about 1 cup of an all-purpose garden fertilizer, such as 12-12-12, and two cups of ground limestone to each bushel of mix. Thoroughly mix these into the medium before filling the containers. When no other soil is available, potting soils for houseplants may be used for potting cuttings.
If a nursery bed is used, thoroughly pulverize the soil, and work in 3 to 4 inches of compost, peat moss or leaf mold. Add fertilizer and lime as directed by a soil test.
Install some shade over cuttings during the first growing season. A shade screen can be made from burlap, snow fencing or laths (Figure 3).
Provide protection to young, rooted cuttings during the first winter season. Mulch them with straw or construct a cold frame around them. Cold frames may be made from concrete blocks or scrap lumber covered with clear plastic, burlap or cheese cloth. If plastic is used, remove it during warm days, or cover it with straw to prevent heat buildup.
After two growing seasons in the nursery bed or container, the young plants should be ready to move to permanent locations.
Place a shade screen over newly rooted cuttings outdoors.