The production of new plants is a subject which could fill a book or for that matter, a website, and there is sufficient space here only to touch on the outlines, but for those who would like to try it, the following will suggest ways which can be studied later in greater detail.
Plants in general, not shrubs specifically, are propagated either by seed or by vegetative means. If grown from seed, the resulting plant will be a totally new one, with some of the characteristics of each parent or earlier ancestors, resulting in a mixture different to any that has previously appeared. Seedlings of natural species are usually much like their parents, but seedlings of hybrids and garden varieties seldom are. If grown by vegetative means, the plant will be exactly the same as its parent, and these methods of propagation include takingof various types, using rooted layers, suckers and runners, division of the parent plant, grafting, and budding (which is a form of grafting).
Propagating shrubs from seed can be rather a slow business since it may take some years for the seedling to reach an appreciable size. The seeds should be collected as soon as ripe and stored dry in a cool dark place through the winter. If one of the berry type, they should be placed in layers in shallow moist sand out of doors during winter, provided they are hardy, as this makes eventual germination quicker.
Sow the seeds in spring in either a standard seed compost or the sort of soil in which the shrub normally grows, space out the resultant seedlings and transfer to permanent positions after two or three years.
Half-ripe cuttings of shoots are taken in July—August, using the current year’s shoots, provided they have not flowered. These are of the kind beginning to harden at the base, close to the parent stem. They should be 2-6 in. long, with the lower leaves cleanly removed, and should be placed in a sandy compost, or moist silver sand, protected by glass in a box or frame, out of doors in a lightly shaded place. Keep the rooting medium moist and when the cutting has rooted, put it into potting compost and grow on as usual.
Hardwood cuttings are taken in October—November from current year’s shoots which are fully ripened, and in which the stem is hard and woody all the way up. These cuttings are up to 12 in. long, and are treated in the same way, but can be rooted out of doors directly into the soil with a little silver sand at the bottom of the hole. The cutting is buried for two-thirds of its length and left over the winter, protected if the weather is very cold. When rooted it is transferred to a permanent position the following autumn.
The production of roots on cuttings, whether half-ripe or hardwood, can be hastened and increased by the use of hormone rooting powders, available at various strengths according to the type of cutting.
Layering of some shrubs is another method. The tip of the stem is placed on the ground in a shallow hole, and bent sharply upwards so as to form a U-shape. It is pinned down in this position and covered with soil. The autumn is the best time to do this, or the spring, and rooting should have occurred by the following autumn. Cutting the shoot a little at the bend, below a leaf joint, will encourage the production of roots.
Germination of seed and rooting of half-ripe cuttings may be encouraged by placing them in an electrically operated mist spray in a.