Propagating Plants: Plant Layering and Plant Division
If you grow garden blackberries or rambleryou may have noticed that, where a long shoot has bowed over and touched the , new roots have formed and have probably even grown into the ground. In fact, the plant has layered itself and is on the way to producing a daughter plant. If you sever the rooted stem from its parent, you can move it elsewhere to grow as an independent plant. We call such a plant a layer and use this technique, “tip- ” to grow more plants.
A branch of most shrubs, including rhododendrons, will throw out roots down its stem if this is allowed to come in contact with the soil. The roots will grow quicker if the bark of the stem has become damaged. Often this happens by accident but we can make it happen too. This also is called layering and it is the easiest way to increase or propagate shrubs. Choose a low-lying branch and select a good vigorous one.
Bend it down and note at what point it touches the soil. At this point make a cut on the underside, so that a little tongue of bark and tissue is formed. This cut must then be set below soil level. Scoop out a little depression and, in this, peg the branch to the soil. It helps if you can place a little prepared rooting compost in the depression. Mix some sharp sand and a little peat with good soil. Let a little of the soil cover the branch.
To ensure that the branch stays where it is, and to keep the soil moist and to act as a marker to remind you where the layer is, cover the soil with a large stone. It will be some months before the layer has rooted enough for you to cut it away from its parent plant and transplant it elsewhere, but you will be able to judge when it is ready by the pull of the roots when you test it. Some people prefer to fill a flower pot with good soil, to plunge it up to its rim and to root the layer in this.
You can also layer carnations. These plants consist of a group of tufted growths, some of which have flowered, some not. For layers, choose non-flowering growths. Bend them away from the plant and note which part of the bare stem touches the soil. Here the stem must be cut or nicked to interrupt the sap flowing along it. The plant will then seek other means — new roots in this case — to support itself.
To do this, cut a little slice in the under portion of the stem. Begin by taking the knife through a joint where the bud lies hidden, and up towards the tip of the shoot, but only for a little way to the base of the next joint. You can now see why this method of layering is called tongueing or heeling, for a loose tongue of stem is formed.
So that it stays in contact with the soil, peg down the shoot. You can use a bent wire or a cleft stick for this. The shoot must be covered with soil so that the cleft stem is buried and you must take care that the cut surfaces are kept open as the soil covers them. So that you have a neat erect plant, stake the end of the shoot so that it grows upright.
You can take any number of layers from one plant, so long as you choose those that have not flowered. It is often best to spread the layers out, making a ring round the centre of the plant. Keep the soil moist and the roots should be formed in a few weeks. Sever the layer from the parent plant in September and plant it elsewhere, any time from two weeks after you have severed it.
For pinks or dianthus, the special type of cutting which we call a piping takes best. You will find the pipings growing quite abundantly round the base of old plants, each being a perfect little individual shoot that has not bloomed. They must be taken from the plant soon after it has finished flowering.
Hold the piping in your right hand and pull it from the parent plant. You will find the stem will be pulled out from a low pair of leaves rather as you pull the hull from a strawberry. It is this soft pull-out piece of stem which will give rise to the roots. But first of all you must remove a few of the lower leaves. Don’t just strip these down the stem in case you injure the tiny bud which forms in the axil of every true leaf and its stem. Instead take a knife or a pair of scissors and carefully snip off the leaf, leaving just the smallest fraction of the base near the stem.
Some people like to trim the base of the piping by making a new cut just below the lowest joint with a sharp knife.
Now you must strike the pipings, and this is best done under cover in the same way as described for cuttings. Insert the pipings about an inch apart each way. You can mix varieties if you wish. You should keep the glass shaded from very bright sunlight; a piece of brown paper placed over it on very hot days will do, or even two leafy boughs set over the glass tent-wise.
Many new plants can be obtained by dividing existing ones. Generally speaking, you can divide them between September and March. If they flower late, then division must wait and follow flowering, not precede it. Not even nurserymen agree about the best season to divide plants. Some for example send out Michaelmas asters in October, others in March.
Another general rule is that one plants fibrous-rooted plants in autumn, sappy-rooted plants in the spring. There is one drawback to this rule — beginners surely are not likely to know what plants have which kinds of roots — but still it is a tip worth remembering.
Old perennial plants are inclined to go bald at their centres. These should be divided so that the good outside pieces are retained. One rule that always irritates me is that gardeners should take two digging forks, place them back to back in the centre of a large root and then pull them apart, dividing the plant. This is all right but I wonder how many gardeners have two digging forks? Often I cut my plants in chunks with one good spade chop! Others can be pulled apart with the aid of a fork.
Perennial plants that will live for years giving lovelyor foliage need not be lifted unless they obviously are becoming old in the centre. Most are best if lifted every three years. Some like , dislike being moved around at all and may not flower the year after moving. You can choose a good piece of the plant to put back in the original site and cut or break the others into nice sized clumps to grow elsewhere. If you have no room in the border, you might consider planting a few rows across the garden somewhere so that you can always have plenty of flowers to pick. If you want to get a lot of plants you can divide a root into really small pieces so long as each piece has a good root.