This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Everybody loves the above Rose; and few plants make such a good climber for the roof, or for training against a back wall of a greenhouse. It delights in being allowed to ramble away at will; but for the sake of tidiness it must be kept somewhat trained, by being tied to wires, or to tacks driven into the rafters in the absence of wires. The leading shoots should be allowed, however, to grow on without stopping them during the whole season, and then cut them back, say in January, to whatever length may be desired; they will then break into growth at every joint, and flower abundantly. Of course, where practicable, they should be planted out in a well-prepared border.
A plan which we mean to adopt in growing this Rose for forcing, and which we think will be a very good one, is to grow it on in pots, as we do Vines for fruiting in pots, either as single rods or by-leading up two or even three shoots from each. They can be grown from cuttings, or, if preferred, may be budded in the ordinary way out of doors, then potted up and brought into some house or pit set apart for the purpose. They would require to be kept trained up to wires, just as we do pot-Vines, and fully exposed to light, but must be allowed to extend their growth without stopping them, else the lateral buds may break into growth prematurely. Where many cut flowers are required, a long succession of blooms might be obtained in this way, by bringing in a few plants every ten days or so to the forcing-pit.
For growing them in this way, cuttings of ripe wood should be put in about the beginning of February in 6-inch pots, well drained, and soil made up of two parts leaf-mould and one part of sharp sand. Put the cuttings in a ring round close to the side of the pots, and plunge them in a gentle bottom-heat: they will soon root, when they must be potted off into 3-inch pots, and placed in a warm house or pit, say in a temperature of about 55°. In the course of two or three weeks they may be shifted into 6-inch pots, and afterwards into 10-inch pots, which latter size is quite large enough for them to flower in. The soil used should consist principally of good loam, with the addition of a little old cow-dung or a sprinkling of bone-meal, with sufficient sand to keep all open and porous. If it is intended to take up more than one shoot, the points should be pinched out when they are about 6 inches high, but afterwards they must be allowed to grow on without pinching. They must be kept in a warm place until May, when they will do very well without fire-heat, if closed early in the afternoon. See that they do not want for water; and a dewing with the syringe at shutting-up time will help to keep them clean.
Give plenty of air during the day, as a close stagnant atmosphere tends to produce mildew; should this appear, syringe them at once with sulphur mixed up in a pail of water: it does not look so bad when applied in this way as when dusted on dry, and is quite as effectual in destroying the mildew. I find that under glass, if not allowed to get dry at the roots, the Marechal Niel is not liable to be much troubled with greenfly; but if any should appear, fumigate in the usual way, or syringe with quassia-water. About the beginning of September the plants may with advantage be removed out of doors and tied up against a wall where they will be fully exposed to the sun: this will greatly assist in ripening the wood, as on this being properly done depends the quantity and quality of the flowers which are to follow. The first batch of plants may be put into heat in January, cutting them back to 8 or 10 feet: 50° will be high enough at first, which may be increased to 55°. They will soon break away into growth: when the flower-buds are showing, give an occasional watering with manure-water. We have been led to make these few remarks from the fact that last year we lifted a young plant from outside and planted it against the back wall of a new vinery planted with the Lady Dowries Grape. It was about the middle of April when the Rose was planted.
It threw out several strong shoots, which were kept tied in, and soon reached the top of the wall (16 feet) - they were then trained along the wires, so that by the end of the season they had made growths of about 30 feet in length. In January these were cut back to about 12 feet, and soon began to burst into growth, every eye throwing from one to three shoots, and all terminating in flower-buds; so that at the present time (May 9th) there are, in every stage of development, on one plant 400 buds, which are regularly distributed over the plant from bottom to top. The plant was green all winter, having never yet cast off the foliage of last year, and shows no signs of doing so - in fact it may be called an evergreen.
J. G., W.