Dahlia.
504. There are two species of Dahlia mentioned in Ifortus Kewensis, D. superflua, and D. frustranea. Of the former there are purple and rose-coloured varieties ; and of the latter, scarlet and yellow varieties. Seeds have repeatedly been ripened in this country ; and the plants from these have become so far acclimated to Britain, that in a few years they are likely to be ranked as hardy perennials.
Till Mr R. A. Salisbury published his observations on the cultivation of Dahlias, they were little known in this country. Being natives of Mexico, they come into flower in October and November, the period corresponding to their usual time in their native country. They may, how ever, be brought to shew their flowers more early. This is accomplished by checking the luxuriance of the her bage, by means of planting the roots in very poor soil, sometimes even in screened gravel. Water is supplied only till the flower-bud be discernible in the heart of the leaves; after which none is given.
The roots, which are large and tuberous, like those of peony-rose or yellow asphodel, are taken up every year, and kept for some weeks in sand. Some cultivators always plant them in pots, the restraint thus imposed on the roots having the same effect as planting in gravel. The growth in the spring may, in this way, be forwarded, by placing them under a frame ; and the pots may be sunk in the dahlia bed in June. If the bed be situate close to a south east or south wall, the flowering of the plants is greatly promoted. The more tender sorts, such as the scarlet variety of D. frustranea, may be placed next to the wall, and have its branches nailed to it, in the way practised with love-apple. All secondary branches are pinched off while young and tender, and even some leaves are re moved, if the plant shew a disposition to be very luxuriant.
Pinks.
505. The common pink and the carnation, though con sidered as distinct kinds of flowers by the florists, have originated chiefly from one and the same species of plant, the Dianthus Caryophyllus of or Clove Pink. It grows naturally in rocky situations in some parts of Germany ;.and Sir J. E. Smith has even given it a place (English Botany, t. 214.) as a native of Britain. Carna tions and pinks seem to have been entirely unknown to the ancients ; for Pliny does not describe them, and the classic poets make no allujign to them.
Pinks were not eld in much esteem by our own an cestors; indeed they seem to have risen to distinction with florists only in the 18th century. They are divided by them into several classes ; such as damasks, cobs, and pheasant's-eyes. The first are white, and flower early; the cobs are red, and flower late. Both of these kinds are considered as originating from D. caryophyllus ; hut the pheasant's-eye, of which there are numerous varieties, is regarded as having sprung from D. plumarms.
When it is wished to propagate good kinds of pinks, this is readily done either by layering or by using cuttings or pipings. This last mode is the most commodious, the pink growing freely in this way. The difference between a cutting and a piping consists in this, that in the former a joint is cut through horizontally, while a piping is drawn from its socket, leaving a pipe-like hollow. The proper time for gathering cuttings or pipings is when the plants begin to come into flower. They are best when between two and three inches in length ; and they should be firm and compact, not drawn. Some part of a bed or border having been worked fine, or the surface soil having been screened by means of a sieve, the pipings are stuck into it at three inches square, and the earth is firmly applied to them with the fingers. A copious watering is then given, and hand-glasses are firmly pressed down over the plants: if the weather be bright, these may have sonic dry earth thrown against them while the glass is moist, in order to produce a degree or shade, or some large leaves may be laid on them for a few days. These hand-glasses are not removed till the new growth of the pinks be dis tinctly perceived, which happens generally in the course of a month or five weeks ; water is however occasionally applied around the covers. The plants are afterwards transferred to a larger bed, or to a garden border, in time to permit them to become well rooted before winter. Slips of pinks, four or six inches long, drawn from the sides of main shoots, and planted any time in the spring, seldom fail to grow.