Unit 256 Collect and prepare propagation material
How to obtain information on plants and plant identification.
There are a number of ways of obtaining information on plants and plant identification e.g.
- From plant labels that are already in place on the stock plants
- From nursery catalogues such as
- From the internet from sites such as
- By asking my supervisor
- From books such as RHS Plant Finder 2011-2012
The ways in which plant material should be handled after it has been collected
There are a number of ways of protecting plant material after it has been collected. The method selected will depend on the material that has been collected.
Soft cuttings can dry out quickly and are often stored in a plastic bag to prevent this until they can be placed in a rooting medium
Also some cuttings are protected by the cut area been placed in water to prevent the cells dying resulting in poor rooting. This can be done in a number of ways such as special containers as used in the photo below.
The methods for collecting propagation material and the requirements of the propagation programme.
Propagation methods
(i)Cuttings
Tip Cuttings: Tip cuttings (taken from the tip of plants) are used to propagate such common house plants as the velvet plant and jade plant. Tip cuttings are generally 3 to 5 inches long and are removed from the parent plant at a point just below a leaf (Figure 1).
Stem Cuttings: Swedish ivy, pilea, pothos, philodendron, fittonia, etc. can be propagated by stem cuttings (sections of stems with leaves attached). The cuttings should have three or four leaves for best rooting. Many outdoor plants such as most herbs, and even tomatoes, marigolds, and flowering shrubs can be propagated this way.
Heel Cuttings: Woody stems fare best for rooting when a bit of the bark is taken with the shoot. This is usually called a "heel" cutting. The best way to get a bit of the "heel" is to bend the woody shoot down and tear it, taking a bit of the bark below the shoot with it. Trim the thin tip off, dip in rooting hormone, and treat it like any other type of cutting. This works well for roses, azaleas, philadelphus, and many other flowering shrubs.
Cane Cuttings: Cane cuttings are used for propagating dumbcane (dieffenbachia - cordyline variety shown at right), Chinese evergreen and similar plants which produce cane-like or leafless stems. The cane is cut up into small pieces 2 to 3 inches long. Place the cuttings on their sides slightly below the surface of the rooting medium (bury it to a depth of about 1/3 of the diameter of the cane). A bud will eventually sprout and form a new stem when the cutting is rooted Keep the soil moist but not wet. Keep in bright light, with no direct sun. Covering with a plastic tent will help hold in humidity as it roots.
When new growth appears, usually at the outer tips of the stem cutting, the plant is ready to gradually acclimatize to room conditions. Lift the plastic or other humidity-retaining covering a bit higher every day for a week. Mist the young plant occasionally. At this point you can repot, planting it a bit deeper and after it is established, you can treat it as a mature plant.
(ii) Budding
Leaf Bud Cuttings: consist of a single leaf attached to a piece of 1 to 1 1/2 inch stem. The dormant bud, located where the leaf stalk joins the stem will give rise to a new shoot and branches. The cutting should be inserted in the rooting medium with the bud about 1/2 inch below the surface. English ivy is easily propagated by this method.
Cuttings from succulents or cactus should be allowed to dry for 1 to 7 days, depending upon species and size, before placing in a rooting medium. The drying period will cause the cut edges to callous. This will prevent the absorption of excessive amounts of moisture that could result in rotting.
(iii) Grafting
Grafting is a method of providing a more delicate plant with a hardy, vigorous rootstock. For rare plants, grafting is the only way of ensuring survival. Rare but desirable natural "sports" can only be propagated this way. Strict attention to hygiene is essential and cutting implements should be sterilized by dipping in methylated spirits or a diluted bleach and water solution.
Grafting Stock: In all cases the stock must be compatible with the graft to prevent rejection, which usually means the same genus or at least the same family.
Flat Grafts: are probably the simplest system for a beginner to attempt, and suitable for plants with fleshy stems (e.g. cacti and succulents). The stock is first cut flat with a single clean cut with a sterile scalpel blade, razor blade or very sharp knife at a suitable height, usually above soil level. The material to be grafted (scion) is then cut cleanly across and the cut surface placed on top of the cut stock in such a way that at least part of the vascular elements just beneath the bark on both pieces are in contact. The graft is held in place with an elastic band which goes under the bottom of the pot at its other end, or with "splints" gently but firmly tied to support the joint.
Side Grafting: is a variant of flat grafting used for relatively thin material in which the stock and scion are both cut at an angle to increase the area of cut stem and increase the chance of the vascular elements beneath the bark making contact. This works well for most fruit trees, and even roses.
Split Grafting: is another method used for thin material, in which the end of the scion is cut into a wedge shape and inserted into a "V" shaped incision in the stock. The stock is then bound tightly with cotton to hold the two parts together. This works best for woody stems, not fleshy ones. This type of grafting is often used to create topiary effects where one part of a shrub is grafted onto another shoot on the same plant - e.g. (Weeping) Ficus Benjamina.
These methods have been gleaned and simplified from web publications and gardening guides. Don't try these techniques at home, unless you are a seasoned gardener and know where to find appropriate rootstock, and if you are ready to deal with the heartbreak of failure...
The Whip Graft
The whip graft is used mostly on young apple and pear trees when the branches are relatively small (not more than ½-inch in diameter) and the understock is about the same diameter as the scion of the new cultivar.
Cut—Cut off a branch of the understock, leaving a stub at least a foot long. Make a straight, slanting cut about 1½ inches long on both the scion and the stock (see A and C in Figure 1). Make the cut straight and even—one stroke with a sharp knife will do it. For the tongue, make a straight draw cut (not split), beginning near the top and cutting about the full length of the level (B and D).
Figure 1. The whip graft is usually used for grafting root stocks and scions but can also be used for grafting small branches.
Union—Match the two parts together (E). Unless the scion and stock are the same size, be sure the scion is in contact with the inner bark on one side. If the toe of either the stock or scion extend beyond the heel of the other, cut if off evenly.
Tying and covering—Bind tightly with tape, then carefully cover the union and binding material with grafting compound.
This type of graft is difficult for the beginner but is used extensively by experienced operators. It lends itself to the tape method of binding. Tape serves to seal the wound and bind the parts together.
While other types of grafts depend on the bark slipping well, the whip graft does not. In fact, it is best if you make this graft before the narrow tongue of wood.
Aftercare—Remove wrapping as soon as the scion has started to grow to prevent girdling of the tree.
The Cleft Graft
The cleft graft is used for topworking older established apple and pear trees, either on the trunk of a small tree or on the side branches of a larger tree. It is best adapted to branches 1 to 2 inches in diameter. The grafts are made within 2 to 3 feet of the trunk or main branches and preferably not more than 4 to 6 feet from ground, or new top of tree will be too high.
Cuts—Select a place free from knots and cut off the stock with a saw. Cut the cleft (avoid splitting if possible) with a grafting chisel, large knife or hatchet. After a few trials you will learn the proper depth of cleft. In horizontal branches, the cleft should be sidewise, that is, not perpendicular, to reduce breakage from birds and storms.
Figure 2. The cleft graft is the one to use on large branches.
With a sloping cut about ¼ inch above the upper bud, cut the scions to include three buds, and to a blunt wedge about 1½ inches in length with one side slightly thicker than the other (see A and B in Figure 2). If the scion wedge is cut to a sharp point there is danger of the bark peeling. Also a sharp scion wedge' will not fit the cleft as well (C).
Union—Open the cleft slightly with a grafting tool or screw driver. Insert a scion on each side, with the inner bark of stock and scion in contact. Have the thick side of the scion outward (B).
Keep in mind that the bark of the larger stock is thicker than the scion bark, so the scion should not be flush with the stock. A very slight tilt will assure a contact, at least where the cambium layers cross (D).
Tying and covering—There is no need to tie, unless the stock is small and does not bind well. Cover the unions with grafting compound and be sure the cleft is covered its full length (E).
Aftercare—Scions that are growing vigorously will need attention to prevent breakage by birds, ice and storms. Either tie the scion to a supporting brace (see B in Figure 3) or pinch back the tips before growth becomes excessive. For additional support, circle all the shoots from one stub with twine (A).
Figure 3. In this example of a cleft graft, three stages in the growth of a branch from a scion are shown.
During the first season, let all scions and the shoot growth from below the graft grow undisturbed. However, do not permit this understock growth to shade out the scions.
The second spring, select the most suitable scion as the permanent branch and consider the others as spares. Leave the spare scions on to assist in healing over the stub, but cut them back to a few buds on each (see B). The third spring, severely cut back the spare scions again. In the fourth season, or when crowding is noted, cut off all of the spare scions as seems necessary (C).
The Modified Cleft Graft
Instead of trying to master the whip graft or side graft, use a simple kind of cleft graft on small understock. Stock (see B) about the same size as the scion (A) may be split and a wedge-shaped scion inserted.
Should the stock be larger than the scion, be careful to set the scion to one side instead of on center (C). In this way the cambium of stock and scion will make contact.
Wrap this graft union (D) carefully with a good grade of rubber tape. As the graft grows the tape stretches and eventually deteriorates. Very large trees are generally poor subjects for cleft grafting, so when grafting their large branches, a slightly different method is ordinarily used.
Carefully saw off the branch undercutting it first to avoid tearing the bark. You may need to recut the stub to get it smooth. Saw the branch to receive the scions, instead of splitting it.
Make two saw cuts about 4 inches deep at right angles to each other across the end of the stub, making a + shape. Then fit the scions into the four places made by these cuts.
The Side Graft
Although the side graft is adapted to a wide range of branch sizes (¼ to ¾ inch diameter), its use is generally restricted to branches that are too large for the whip graft yet not large enough for the cleft graft. As the name suggests, the scion is inserted into the side of the stock, which is generally larger in diameter than the scion.
Cuts—Select a smooth place on the understock branch at least a foot from the trunk. Make a slanting cut at a narrow angle almost to the pith (core of the branch) (see B in Figure 5). Cut the scion to a short, sharp wedge (about 1 inch) with one side thicker than the other (see A).
Figure 5. In the side graft, the cut goes across the grain to reduce splitting.
Union—Bend the branch slightly to open the cut. Press the scion in so the cambium layers of the stock and scion meet at one side (C).
Tying and covering—Tying is unnecessary if the stock binds well, but you may have to tie small materials if the scion is not held firmly. Cut surfaces should then be covered with grafting compound (E).
Aftercare—In about two weeks, cut off the stock above the union (D) using sharp shears in order to avoid disturbing the scion. Then cover the cut surface with grafting compound (D).
If the graft has been tied, cut the binding shortly after growth starts; this will prevent girdling. In the first season, you may allow some shoot growth from below the graft, but do not permit this growth to shade the scion growth. After the first season, all growth should be cut off, except that of the graft.
Inspect grafts during the growing season to guard against faulty covering or binding. If shoots are attacked by fire blight, cut them 6 inches below the visible symptoms.
(iv) Micro-propagation
Micropropagation can be defined as:- growing plants from seed or small pieces of tissue under sterile conditions in a laboratory on specially selected media. This is performed in a carefully controlled environment. The media that the plants are grown on contain a carbohydrate source, a range of mineral salts and agar. Sometimes vitamins, amino acids, growth regulators or plant extracts may be added to encourage growth.
Micropropagation begins with the selection of plant material to be propagated. Clean stock materials that are free of viruses and fungi are important in the production of the healthiest plants. Once the plant material is chosen for culture, the collection of explant(s) begins and is dependent on the type of tissue to be used; including stem tips, anthers, petals, pollen and others plant tissues. The explant material is then surface sterilized, usually in multiple courses of bleach and alcohol washes and finally rinsed in sterilized water. This small portion of plant tissue, sometimes only a single cell, is placed on a growth medium, typically containing sucrose as an energy source and one or more plant growth regulators (plant hormones). Usually the medium is thickened with agar to create a gel which supports the explant during growth. Some plants are easily grown on simple media but others require more complicated media for successful growth; the plant tissue grows and differentiates into new tissues depending on the medium. For example, media containing cytokinins are used to create branched shoots from plant buds. and it happens in a vegetative form
Plant Division
Division.
This is often a quick and easy method of propagation. The parent plant is divided up (cut into sections) this normally involves taking a section of the root and stem and planting in in a rooting medium until it established. This is often done with herbaceousperennials.
Layering
Runners
Runners are prostrate creeping shoots or stems, such as strawberry geraniums, can be used to propagate house plants. Place the leafy cluster of the runners in contact with a sandy loam soil in a second pot and hold them down with a paperclip or similar item (Figure 6). When roots have developed from the cluster, the new plant can be cut free from the runner. A simpler method would be to cut off the leafy clusters along with a small section of stem and root them as tip cuttings. Better success rates occur for runners that are left attached to the mother plant. Many groundcover plants can also be propagated this way by assisting the young runners to root in the garden soil nearby.
Offsets
Many plants produce small plants at the base of the parent. These offsets (often called suckers when they appear around deciduous shrubs like lilacs and dogwoods) can usually be easily pulled or cut off the main plant and potted up individually. The main plant often benefits from removal of offsets which can divert energy from the main stem, and removal of offsets may be essential to the production of a large solitary specimen.
Other species produce miniature plants on the edges of leaves, flower stems or flower heads, and these can also be removed and potted up. Succulents, lilies and Egyptian Onions are examples of plants that produce small bulbs or mini-plants on above-ground growth.