This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
As a rule, plants to be propagated from at this time of year should be in a free-growing state. We advise placing old plants of verbenas, petunias, etc., in a moist heat, in order to start them for cuttings, because the best cuttings are those of shoots newly formed, and the worst those from shoots of last year. Indeed, these latter are of no use at all, except in the hands of the professional propagator, and he would never choose them while young shoots were obtainable. If the plants are not freely growing therefore, the propagator must wait for them; and to promote free growth, the temperature of the house should be kept at from 60° to 70°, with a moderate amount of atmospheric moisture, and as much light as possible, so that the young shoots will be of a healthy green, and with short joints. But at this time of year, the plants the amateur intends to cut from will be for the most part full of young shoots, and the removal of a crop of these will cause the thumb against it, and it will snap away "with a heel" - that is, with a thickened base, the separation taking place at the point where it issues out of the old wood.
When you have removed it, it will probably have such an appearance as in fig. 84. All that this requires for its preparation is to remove the bud which has 10 - May. the plants to throw out more, and the question arises, how are the cuttings to be made?
Suppose we look over a lot of fuchsias now, we shall find them full of little stubby side-shoots all ready to hand, without demanding any particular skill to remove them. Select one of these plump shoots, of an inch or an inch and a half long, press just started near the base of the cutting, so as to leave a sufficient length of clear stem to insert the cutting in sand firmly. When so inserted, and kept moist, warm, and shaded, roots will soon be formed at the base; and as soon as the roots have begun to run in search of nourishment, the top of the shoot will begin to grow, which is the sign for potting off. But suppose we have a chrysanthemum instead of a fuchsia. This will hare a mass of tender shoots rising from the root, and there is no need to seek to take these off with a heel. With a knife, a pair of scissors, or the thumbnail, remove a small shoot of not more than three inches in length - two inches will be sufficient. This will probably hare some such aspect as in fig. 85. All the preparation this requires is the removal of the lower leaf, to make a sufficient length of clear stem for inserting it in silver sand. Or suppose we have a hard-wooded plant of robust growth, and which is known to be easily-rooted, then we may venture to take a still larger cutting.
Here is a side-shoot of Veronica Lindleyana (fig. 86); it consists of four joints, is young, the wood not yet hardened, and needs no preparation at all, because there is a proper length of stem for its insertion. But in the case of plants having large fleshy leaves, it may sometimes be needful to crop off half of every leaf except those next the top bud; but, as a rule, as many leaves should be allowed to remain as possible, because the more leaves that can be kept alive while the cutting is making roots, the quicker will it become a plant. No definite rule can be given on this head to guide the inexperienced. It all depends upon how many leaves can be kept alive. If the cuttings are to enjoy a brisk heat, say 70o, with plenty of atmospheric moisture, then nearly all the leaves may be left entire, and especially if the cuttings are in a close propagating frame, or under bell-glasses. But if they are likely to be exposed to •draughts, if they are placed in pots or pans in an ordinary green-house, and thus much subjected to evaporation, the leaves must be reduced in number, and all the larger ones must be cut half away.
Another matter of importance in making cuttings is to determine whether they are to be rooted from a joint or not. Most cultivators prefer to cut the shoot close under a joint, so as to obtain roots from that joint. But there is no occasion to cut to a joint; any and every one of the plants ordinarily propagated at this time of year will root as quickly from the "internode" - that is, the portion of stem intermediate between two joints - as from the joints themselves. This is of great importance when cuttings are scarce, as a shoot will often furnish half a dozen cuttings, if taking them at a joint is of no consequence; and only one or two, perhaps, if taking them at a joint is imperative.
The size of the cuttings is a matter of great importance. As a rule, the smaller they are the better. Still, if very soft, many may damp off unless very skillfully handled, so the amateur must secure them moderately firm. Three or four joints will generally suffice of most things, or say nice plump shoots of from one to two inches long. If young side-shoots are scarce, longer shoots may be cut up in lengths of three joints; and if it is a question of raising the largest possible number of plants from the fewest cuttings, then one joint and its accompanying leaf will suffice. Suppose we have a shoot of a verbena placed in our hands to make the most of it; we should first cut it into as many lengths as there were joints, leaving each leaf untouched, and to every joint as much stem as could be got by cutting just ocer instead of just under the joints. Then with a sharp knife we should split each of these joints in half, so as to have one bud and leaf to each split portion, and from every one of these we should expect a good plant. "We say nothing now of propagating from leaves, etc., because we are writing for beginners, and all the higher departments of propagating are from time to time dealt with in these pages as occasion renders necessary.