Propagating Plants: Taking Cuttings, Making Layers and Dividing
As you may know, many plants can be raised from cuttings – this is the name given to portions of plants such as stem, leaf or root which will root when detached from the plant and placed in a suitable material. We talk of striking cuttings. Not all are easy to root, but since so little time and money are involved they are well worth trying.
Leaf cuttings are mainly taken from house and. Some will root merely by being placed in water, others by being pressed into a box or pan of sandy or a half peat, half sand mixture. So long as the underside of the leaf lies flat on the rooting medium it should root. Some large leaves, ones like the Begonia rex are often secured by hairpin-like wires passed over the main veins. The leaf becomes more readily rooted if these veins are slit quite drastically every inch or so, so that the result is a very ragged leaf indeed. Roots appear at these cuts and little tufts of leaves, crowns, often appear too so that from one leaf more than one plant can be raised. Leaf cuttings need a warm, and if possible, moist atmosphere. Bottom heat is often recommended. Gardeners without a greenhouse can provide this if the cuttings are stood on a shelf over a radiator so long as the box or pan is safely and moistly enveloped in a transparent plastic bag. Not all leaves will root.
Root cuttings of some plants will grow. Best known are anchusa, hollyhocks (a good way of propagating a particularly good coloured variety), gaillardia, phlox, oriental poppies, perennial statice, verbascums. Some roots will be very much thicker than others but this seems to have no bearing on the ease with which only a few plants become propagated this way.
In winter, portions of the root, 1-1/2 to 2 inches long should be placed either upright or on their sides in the rooting medium just below the surface. Since most of the plants are hardy, the cuttings may then be kept in a cold frame or in an. They should be ready as little plants for transplanting by the next summer.
Most cuttings are stem cuttings. These are divided into soft stem, half ripe or hard wood sometimes called “naked” cuttings. Most soft cuttings are taken at the nodes or joints. Obviously the length of a cutting will depend upon the type of the plant, but the general rule is to find a shoot with three or four joints, not counting the growing tip.
Soft types of cuttings lose moisture easily and quickly. They can be helped if you can keep the air round them moist. Some will root uncovered in a pot, box or frame but it often helps if they are placed under a bell glass, a cloche or in a polythene tent. An easy and efficient way is to take a transparent plastic bag and slip the filled pot inside it or cover the top of the pot with half of a clear plastic bottle. If using a plastic bag, it should then be inflated and secured so that it is virtually airtight. There will be condensation and so long as this appears as a light mist over the inner surface of the bag, all is well. If, however, you have made the rooting medium too wet, the condensation may be so heavy that it will cause the cuttings to rot or to damp off. The best thing to do in this case is to remove the bag, turn it inside out and slip it back on again and secure as before.
A propagating frame or box is sometimes used for propagating plants. This is placed on the staging of a greenhouse or on a warm window sill. This is a small box with a closed transparent lid. The box is half filled with peat or other similar material which is moistened and the boxes and pans are stood on this. If bottom heat is added, roots form very quickly but guard against creating too much moist heat or fungus will attack the cuttings.
Soft cuttings root very easily in sand, which may be used instead of a cutting soil mixture, but when this is so the cuttings must be transferred very quickly from sand to soil once they have rooted, or they will become starved. If you can get them growing quickly after rooting you get a. much better plant.
Although cuttings may be given individual pots one popular method is to insert several cuttings round the rim of a clay pot in such a way that they actually touch the cool inner surface. This not only saves space and time but appears to be beneficial, because cuttings really do root quicker when struck this way. At least one-third the length of the stem of a cutting needs to be inserted in the rooting medium. No leaves must be allowed to remain on the portion to be inserted. Trim them off with knife or scissors. Roots form round the underground joints where the leaves grew.
Many shrubs, including heathers, are propagated by taking half-ripe cuttings, those shoots which have not yet become really woody but are all the same, nearly matured. They are usually taken at midsummer, June, July and early August. These are often, like the soft cuttings, taken at a joint or node, and so are known as “nodal” but many more are “heeled”. These cuttings are side shoots which are not cut or nipped from a plant. Instead they are pulled downwards in such a way that a heel of the tissue of the main stem comes with them. It is known that the cells in this area initiate roots quickly. The heel needs trimming though to remove the very end which might decay. The lower leaves on the shoot should also be removed.
It is possible to divide a long (over six or seven inches) heeled shoot into two. The tip heel-less portion should be cut just under a leaf joint or node. Remove its lower leaves. Heels are not essential but heeled cuttings usually will be found to root quicker.
You do not need to take quite so much trouble over these and hard-wood cuttings because they do not lose so much moisture. A frame or a propagating frame in a greenhouse is most generally used for propagating plants by taking cuttings, so that the atmosphere will still be warm and humid but not excessively so.
Less trouble still are the hard-wood or naked cuttings. As one might expect, little moisture is lost by these; they do not need a special climate and may be rooted outdoors. Many currants and other hardy shrubs will stand the winter without any protection but evergreens are generally inclined to be a little more tender and these are best taken in a cold frame, or under a cloche. This does not mean to say that the light (the cover) of the frame must be left on all the time. It is needed in severe weather only. It is important that these cuttings be well-ventilated. Some people use a frame cover made of thin laths of wood.
Hard wood cuttings are taken in October or November, at the end of the growing season when the wood is ripe. This means that they are necessarily divided into deciduous and evergreens. All of them are likely to be much larger than the other types previously discussed. Evergreens must be stripped of the lower leaves.
To contain the hardy cuttings, make a trench in the open ground but choose a spot as sheltered as possible. The trench is easily made by inserting a spade for a little way into the soil and levering it so that the back is straight. Line the bottom of the trench generously with coarse sand. This will promote root growth and it will also help to keep the trench well-drained. Place the cuttings along the straight back, two or three inches apart and from two to four inches deep. Replace the soil round them so that the base of each one really is in contact with the soil. Then press each cutting in firmly by treading round it.
Most cuttings wilt a little, but this is nothing to worry about. The very fact that they flag a bit means they will begin to push out roots in search of water. When they perk up, you can be pretty certain that they are rooting.
The quicker the roots are formed the better. It is possible to buy certain rooting hormone powders or liquids to speed up this process. Some cuttings are just dipped in the powder before being struck, sometimes the powder is mixed with the soil. Other times the cuttings are stood in a solution for 24 hours or longer. Usually “hard” cuttings, those taken from woody shrubs or plants, need longer preparation. You will find directions on the packet or bottle.
The speed with which roots are formed varies according to the type of the cutting. If all conditions suit them, the soft types should root in three or four weeks. Half-ripe cuttings taken in the summer should be ready for transplanting into pots or nursery beds by autumn. Hard wood types are slow to root, often not starting until the spring and will not be ready for transplanting until about a year after they were taken.
I often strike cuttings in rows in a bed in a frame, for I find this less work than filling pots with cutting sand or soil. I have found it best first to spread a layer of ashes, for this appears to discourage slugs as well as to ensure good, then on this to spread a three-inch layer of the mixed soil and then finally a thin layer of silver sand. If only a few cuttings are to be taken, just a section of the bed of the frame is prepared’ in this way. The cuttings should then be dibbled in, spaced about an inch apart all ways. As the dibber is inserted and removed, and the cutting put in its place, some sand will trickle in — a good thing for this aids rooting. The soil must be pressed firmly round the cuttings.
If you have no frame, you can convert a bottomless box to hold cuttings. A pane of glass or clear plastic should be placed on the top when soft cuttings are taken. It is a wise precaution to stand pots containing cuttings on ashes.
You can also make a good temporary frame by using the warm wall of your house, so long as this will not look too unsightly! Do not choose a spot where the mid-day sun strikes full, for frames need partial shade. Make a wooden frame to the size that will be practical. Fill up with peat and top with a layer of sand or soil and sand and cover with polythene. If you have an old window frame for the “light” or cover, so much the better. If you want to do the job really well, you can install an electric soil heating unit.