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.
Some months ago, a correspondent, a lover of these sweet plants, whose efforts at their cultivation had not been rewarded with desired success, asked me to write an article on their cultivation in 'The Gardener'; and as I find the subject has not lately been treated of in these pages, I the more readily accede to the request.
Perhaps the most important matter in the successful cultivation of these plants consists in having a properly prepared compost for growing them. The finest plants, yielding the most satisfactory crops of bloom I ever remember seeing, were grown in rather heavy turfy loam that was stored, but not required, for a vinery border. It was stacked in ridges, with one-fourth its own bulk of clean horse-droppings, and once, during frosty weather, thoroughly saturated with cow-urine. The soil on the sites of the intended beds (a heavy clay) was removed to the depth of 2 1/2 feet, and some lime-rubbish put in the bottom to secure thorough drainage; for although these plants thrive best in a cool, moist soil, stagnant water is very injurious to them. When the soil was placed in the beds, a very little leaf-mould was mixed with it, and the plants planted, 15 inches apart, about the end of March - and they did splendidly. I have also seen them do well on the same soil when the under layers of the clay were burnt and mixed with the best of the natural soil, with the addition of good, well-decayed stable-yard manure.
In light soils it is advisable to procure some heavy soil for the purpose of giving it more body; for although the plants thrive tolerably well in light soil if in fair condition - more especially Pinks - yet a somewhat heavy soil gives flowers of greater size and substance.
After the plants have begun to throw up the flower-stems, they will require to be tied to neat stakes to prevent them from being blown over by wind when they are coming into flower; for when this happens, not only are the flowers spoilt, but the plants are injured into the bargain. If the blooms be wanted for exhibition, a little manure-water, given while the stems are running up, but withheld before the flowers open, will assist them greatly. If too strong, or if applied too late, it may cause the colours to "run." To produce the very finest blooms, remove all the flower-buds except the main ones. To insure the bloom opening regularly, it may be necessary to tie the calyx with a bit of matting, and to slit it with a thin sharp knife, when one side bursts before the other. Shading from the hot mid-day sun, and from dashing rain, will secure flowers in the greatest perfection for the greatest possible time.
They are easily propagated by cuttings; but I prefer layers. If cuttings are taken, July, or early in August, is the proper time; and moist weather is to be preferred. The cuttings should be put in a shady place, in light soil, with a dash of sand in it, covered with a hand-glass, and properly attended to with water, so that they are not allowed to shrivel. But cuttings never make so robust plants as layers; and therefore layers are recommended. The way to layer them is to scrape away the soil to the depth of a couple of inches round the old plant, and to mix the displaced earth with some leaf-mould and a little sharp sand. Then select suitable shoots, strip the leaves from the part of the stem to be buried in the soil; and then, with a sharp knife, enter the shoot half-an-inch below the joint which is intended to be the base of the new plant, and run it up right through the centre of the layer, an inch, or an inch and a half beyond it, removing the lower half-inch of the "tongue" just below the joint from which the roots most readily proceed.
When all the shoots of a plant are thus prepared, fill in the little hollow with some of the prepared soil, and set the layers upright in it, fastening them in their places with hooked pegs, and then cover in with the remainder of the soil.
Watering in dry weather is necessary; for if the weather prove very dry, no roots will be emitted. In October, these will require to be lifted and placed in some sheltered place, where a little protection can be given. In dry soils, I have often seen them keep at the bottom of a south wall, or under hand-glasses, very well; but in heavy soils they are apt to rot off in such quarters, and slugs and snails often eat them up wholesale; therefore I recommend that they be kept, during winter, in a cold frame. My practice has been to put 2 inches of rough stones, or clinkers from the furnaces, in the bottom of the frame, and over this 4 inches of ashes, placing 6 inches of light loam, mixed with some leaf-mould, and a little sand sprinkled over the surface; and by this means they winter in good condition. A word of warning here to amateurs. The frame is only for keeping them dry. If they are kept close they will grow; and the growth made during the dark days of winter cannot stand damp, frost, or even hot sun.
So give air night and day at top and bottom in all weathers, never closing the frames unless the plants are safely frozen up; and then the light may be put close down.
To those who have to supply large quantities of flowers, which are more appreciated when they are sweet smelling, I can strongly recommend seedlings. They flower much more profusely than the fine-named kinds, and are of very much greater strength. Seedling Carnations and Picotees flower on until the frost stops them; and some of our old plants are of a size, and have yielded a supply of cut-flowers quite unapproached by the fine-named kinds. True, seedlings are not so good from a florist's point of view; but if got from a good strain, they are equally useful for cut-blooms, and I think they are sweeter scented. At any rate, they do not require half so much trouble, either in growing or in wintering, and they are much better fitted for hundreds of gardeners who have often to grow, not the finest, but what will keep the supply equal to the demand. Seed can be sown during April in cold well aired frames, where the soil is heavy and slugs abound; otherwise a sheltered border will do very well. When large enough, they can be pricked out at suitable distances, and finally-put into permanent quarters in August or September, or during March the following spring.
If well grown, they will bloom well the first season, but much better the second, when they yield an enormous amount of bloom for cutting. The mixed herbaceous border is a good place for them; and they will increase in size for some years if the soil be suitable. A. H.