| | Cuttings | Divisions | Air layering | Runners | Offsets | Seed
Plants are easily grown at home from seeds, or vegetatively from sections of established plants. Vegetative reproduction is quicker than starting with seed, and produces an exact replica of the parent plant. As a drawback there is no guarantee that variegated varieties can be reproduced in variegated form unless seed is used.
Cuttings
Taking cuttings is the most common method of vegetative reproduction because it is simple and successful with most plant varieties.
Leaf cuttings
Any plant with fleshy petioles (leaf stems) such as pepperomia or African violet can provide leaf cuttings. Using a clean sharp blade, cut off a healthy leaf at the point where it joins the stems. Insert the petiole in moist rooting medium. Place the leaf at an angle so that new plants developing at the base will not be shaded from the sunlight. Cover the pot and place in diffused daylight until growth appears.
Another method of propagating leaf cuttings is used for plants with fleshy-veined leaves, such as African violets, begonias and kalanchoes. Remove a leaf and make slits in the heavy primary veins from the underside. Lay the leaf face upwards on moist rooting medium. To ensure the bottom of the leaf is in contact with the soil, anchor it with small pebbles. Place the pot in a warm, humid location with diffused daylight. New plantlets will develop from each slit. When each has established a good system, replant them individually in potting soil. Sansevieria can be propagated by cutting a leaf horizontally into 8 cm sections. Each section is inserted 2.5 cm deep in rooting medium. Variegated varieties propagated in this manner will usually develop as solid green plants.
Stem cuttings
Stem cuttings are suitable for most house plants. Choose a sturdy shoot. If a shoot is brownish and tough, it will lack the vigor to establish new plants; if it is light green and succulent, it will be prone to rot. Cut the shoot off about 5 mm below a leaf. It should be about 10 cm long, bearing at least four or five leaves. Remove the leaves from the bottom portion, leaving some at the top to carry on food production while the plant develops roots. Immediately insert the cutting in moist rooting medium, ensuring no leaves touch the medium. Cover the pot with a plastic bag or an inverted glass jar to provide a moist atmosphere and prevent wilting. Place in a warm location out of direct sunlight. When roots have developed and the cutting shows signs of growth (taking about three to six weeks), transplant into potting soil. Provide high humidity for about two weeks until active growth begins.
Cuttings will root more rapidly if dipped first in rooting hormone. This chemical stimulates and speeds root formation and can be useful for difficult or slow-rooting varieties. Rooting hormone is available in florist shops and garden centres, and is sold in three grades. For house plants, no. 1 or no. 2 rooting hormone is suggested. Pour a small amount of powder onto a piece of paper. Dip the lower end of your cutting in water, let the excess drain away, and dip it in the powder. Shake the cutting to remove surplus powder; too much can destroy the plant. Insert in moist rooting medium.
Some cuttings can be rooted in water. However, their roots tend to be more succulent and weak, and they may have later problems adapting to potting soil. Cuttings develop a sturdier root system and survive the transplant into pots better if they are rooted in a solid medium.To root a cutting in water simply place it in a jar full of tepid water until roots develop. Using colored glass and changing the water regularly inhibits algal growth. To anchor the cutting, insert it in a piece of wire mesh. Plants that root well in water include ivy, philodendron, wandering jew, geranium, coleus, African violet and syngonium.
Large foliage plants with thick stems such as dracaena, philodendron, dieffenbachia and aglaonema, will reproduce from stem sections. Cut the stems into 10 cm sections and dip the ends in sulphur or fungicide to prevent rot. Lay the sections horizontally on moist rooting medium and press down lightly. Plantlets will develop from the eyes (undeveloped buds). These can be removed and treated as cuttings. Each eye will continue producing shoots as often as they are removed.
Rooting media
A rooting medium must have an open structure to provide air passage throughout, and to allow the young tender roots to penetrate. It is essential to sterilize the medium (particularly if it contains soil) beforehand to protect new growth from harmful micro-organisms. Spread it out in a flat pan, moisten thoroughly, and bake in the oven at 85 C (180 F) for 30 minutes.
There are a variety of materials to choose from; you may want to experiment to see which works best for you. Any of the materials listed may be used alone or in combination:
- Coarse builder's sand (not salty beach sand) is cheap and effective; it drains well and allows air and root penetration. The addition of peat increases the moisture-holding capacity of sand, which speeds root formation.
- Perlite is frequently used. In addition to its porous structure it has a high moisture holding capacity.
- Vermiculite is porous and lightweight but tends to become soggy and messy when used alone.
- Sphagnum moss and peat can be used if previously soaked in hot water to make them absorbent.
- Soil by itself is too heavy to allow root development, but can be mixed with sand or perlite.
A warm humid atmosphere encourages rooting; it is easily provided by covering the cutting with plastic or inverting a glass jar over the container. Cuttings should be kept out of bright light until established. Any container, from a plastic box to a casserole dish, can be used to propagate new plants.
Divisions
Any plant with more than one stem rising from the soil, or which develops multiple crowns, can be propagated by division; ferns, clivia, African violet, aspidistra, spider plant, sansevieria, maranta, and epicia are all suitable.
Remove the plant from the pot and shake off the soil. Some plants can be pulled apart, but others you may separate by cutting down through the crown with a sharp knife. Each section will need some root and a section of crown. Repot each division, ensuring the plant's soil level is the same as before. Water thoroughly and keep out of sunlight until the plants are well established. For some plants, such as ferns, cut off some of the upper foliage to encourage growth.
Air layering
This propagating method is used for plants that are difficult to root or tend to grow long and leggy, such as philodendron, dieffenbachia, Norfolk island pine, aglaonema and rubber plant. About 20 to 25 cm from the tip of a branch and below a leaf node, remove a strip 25 mm long from around the stem, or make a slit one-third through the stem, and insert a toothpick to keep it open. Wrap moist sphagnum moss around this section of the stem, securing it with string, and cover it completely in plastic. Secure the plastic tightly above and below the moss with strings; an airtight seal is essential to prevent the moss from drying.
When roots appear through the moss ball, sever the stem below the moss and plant the top portion. This may take from three weeks to nine months. Newly-potted plants should be kept in a moderately lit, humid location until they are established.
Runners
Plants such as saxifraga (strawberry plant), chlorophytum (spider plant) and espiscia send out long horizontal shoots from the crown of the plant. At the tip of the runner small plantlets develop which can be rooted as new plants. Lead a runner to the top of a soil filled pot and fix it to the soil with a hairpin or piece of wire. When roots form in two to three weeks, cut the runners off.
Offsets
Offsets are branches developing from the base of a parent plant and clustering around the original plant. These can be cut off close to the stem and treated as cuttings. They will develop roots if inserted in moist rooting medium and kept in a warm, humid location. Offsets develop on bromeliads, sansevierias, agaves and gesneriads.
Seed
Seeds can be grown in any container; you don't need a special seed propagating case. The medium you choose should be firm and dense yet porous; and most important, sterile. Fungi carried in the soil are the cause of damping off, a common seedling disease. Mixtures of sand, perlite, peat, vermiculite and soil are used because they are uniform and porous and hold moisture well. Soil alone is too fine. Compact-roots are slow to develop in soil because air and water cannot reach the seeds, and the small seedlings are difficult to transplant.
Sand tends to become too dense with excessive moisture, and retards germination; it should be mixed with soil. The sharpness of the sand granules may injure tender roots. Vermiculite, moist sphagnum moss and peat can be used alone.
Sow seed sparingly and evenly, so the young seedlings will not be overcrowded. Fine seeds should not be covered; press them lightly in place. Large seeds are best sown to their own diameter in depth.
Cover the container with plastic or a glass lid. Place them in a warm spot, away from bright light. Continual warmth, between 20 and 25°C is necessary for germination of most seed. Some seeds require cool temperatures to germinate. These should be kept under lights in a cool basement. Check daily to ensure the soil is evenly moist, but never wet. Young seedlings are easily killed by drought. To avoid dislodging seeds and rootlets, water from the bottom.
When the second set of leaves is up and the seedlings appear well established, pot them individually in potting soil and give them light. They will not need fertilizer until they are larger.
Adapted from Agdex 285/20-7. |
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