Propagation involves using certain varieties of perennials to create new plants. Various methods of propagation are available. The basic methods include cuttings, division of old clumps, propagation from leaves, and budding. Some varieties can use any all methods, while some can only use one method.
Cuttings
Cutting refers to the process of removing a small portion of a growing plant and treating it so it develops roots. Once it has roots, it can be transplanted and will, in time, produce its own blooms. Cuttings typically are made from a portion of the stem, from leaves, tubers, or from roots. Cuttings should be rooted in a mixture of sand and peat moss. Some varieties can be encouraged to root in water, in sphagnum moss, or in light, sandy soil.
For softwood cuttings, coming from the wood stem of soft-stemmed plants, insert small pieces of stem about 2 or 3 inches long in 4-inch deep (or deeper) planting pot, with about one-half their length exposed. Try to keep the cuttings in the shade. Place the flowerpot in another pot filled with water, so that there is a steady seepage through the porous clay. The hole at the bottom of the pot should be tightly plugged with a cork.
Most all perennials can be propagated by cuttings. The clipping is made at a sharp short diagonal, just below a node or joint. Wrap the cutting in damp newspaper and expose it to the air for a half-hour or more. This will not work for plants that give off a milky juice. Theses cuttings should be sprinkled with water and exposed to the air for two hours.
Leaf Propagation
Leaf propagation is a possibility for many perennials. Plants with thick fleshy leaves, like begonias and gloxinia, are good choices for this method of increasing their number. Insert the leaf stem in the rooting medium then care for it in the same way you would cuttings. You can, for some plants, propagate them by placing the leaf flat on the rooting medium and weighting it down with pebbles.
Make a slight cut through the main vein of the leaf. Using plant hormone will materially improve the chances of propagating successfully from leaves, even for those plants generally considered difficult to propagate by this method. Hormones work well with holly, magnolia, rhododendron, azalea, taxus, and many others.
Propagation by Division
Dividing up clumps of plants is the easiest from of propagation. It is also good for the old plant that is being divided. Many perennials will begin to go stagnant if left in clumps for too long. The division allows for continuous health and growth. Carefully remove the plant from the soil, in clumps, and divided by carefully pulling them apart.
Be very careful when diving to protect and not to injure the roots. Divided plants will need to be planted in a pot, unless the division is done early in spring, then the new clump can be planted in another section of the garden. The new planting should be well fertilized and watered.
Layering
Layering is also a simple method of propagation. However is only applicable to those plants which root easily when their stems are in contact with the ground. Broad-leaved evergreens in particular do well with this method. Simple layering involves anchoring the supple stems of plant into the adjacent soil by bending them over and burying them into the soil.
Black raspberries are perfect for this type of propagation. For plants with less supple stems cut a notch about 18 inches from the tip of the stem and prop it open with a twig or sliver of wood. The branch can then be bent to the ground, and cover the notch part with soil. This type of layering should be done in spring or summer. Leaves should be removed from the stem which is being used for propagating.
Serpentine layering is used for vine-like plants with long supple stems. You can get a number of plants from a single stem by covering it with earth at different points. Leave the tip exposed, however. Air layering is a modern method that is becoming more popular, adaptable to trees and woody plants.
A portion of a straight branch or stem should have the bark removed to the wood, and covered with moist sphagnum moss, which must be kept damp. Some manufacturers provide plant food and hormone which should be rubbed into the cut, as well as a plastic wrap for the moss which has plant food in it. After the notch or stripped area has rooted well, the branch is cut off and replanted.
Seed Propagation
Seeds are another way to grow annuals. Growing this way really depends on how hardy or delicate the seeds are. Some seeds may need to be planted in frames or pots initially and then transferred to the bed once the weather is milder and the plant is well grown.
Perennials and biennials can also be propagated from seed. Although this will not work for all perennials, where some of the other methods discussed will create better results. Typical perennials which can be propagated from seed are:
- Hollyhock
- Christmas rose
- Columbine
- Bleeding heart
- Baby's breath
- Foxglove
- Butterfly weed
- Primrose
- Larkspur