Dear Sir - As the winter flowering of roses is a matter of some importance to all lor-ers of flowers, perhaps a few plain directions by which they may be successfully grown and brought to bloom with little trouble or expense, from November till May, will be of service in your journal.

My present purpose is with the amateur and those having small green-houses managed by themselves, without the assistance of professed gardeners. How many of these structures do we see which are in themselves unsightly objects, but which, by a little more towards perfection, or be better paid by wrapping its details in mystery. Disseminate and diffuse knowledge, and the more extensively and enthusiastically will it be sought after, the greater in number will be its proselytes, and the more the demand for those who practice in its various spheres. Circulate experience, and pedantry will fly before it. Extend true practice, and pretension and empty boastings will hide their heads, leaving an open field for improvement.

But to my point. In the first place, select in the spring as many good stout bushes as there is house-room for, and let them be of the following kinds: (Chinese) - Queen of Lombardy, Mrs. Bosanquet, Agrippina, or Cramoisie superieure, old China, and Triumphant. (Tea scented) - Antheros and White Tea. (Noisette) - La Pactole. If there is room for spreading branches, Lamarque and Cloth of Gold, or Solfaterre, may be added, which, if allowed to grow without being shortened-in, will bloom freely. (Bourbon) - Hemosa and Souvenir de la Malmaison. Place these in pots suitable to their size, in a mixture of two-thirds rough turfy loam, and one-third good rotted stable manure, (incorporated well together, but not made fine.) Let the pots be well drained, and prune in the plants rather close; plunge the pots in the soil on a dry bottom in a shady place, for the summer. In the fall, if they have filled the pots with roots, and have made corresponding top growth, remove them into larger, being careful not to break the ball of earth; but do not remove them unless they require it.

If not repotted, some of the surface soil should be removed, and the pot again filled up with fresh compost of the same kind.

If the foregoing preparation of the plants has not been made in the spring - the following course may be pursued. Lift carefully about the middle of September, a sufficient quantity of good plants of the foregoing sorts, and pot as above directed. These will not bloom so abundantly in November and December, though quite as much so afterwards About the beginning or middle of October, according as the weather is mild or cold, wash the pots clean, and remove them into the house. At the same time prune away any dead or weak spray, place as near the glass as possible, and exposed to the sun. (The old exploded tan-bed is of little use where this is attended to.) Admit air freely over the heads of the plants, but by no means from front lights or outside doors, which only produces cold and damp under drafts. This point, in all plants growing in glass structures, is not sufficiently attended. It only reduces the temperature below, leaving the head of the plant warmer than the roots, causing stagnation to the growth, and encouraging, (in this climate more particularly,) the progress of fungoid vegetation, the sporules of which are contiuually floating in countless myriads in the atmosphere, ready to develop themselves upon various plants under favorable circumstances, the result of which is mildew or blight, in its various forms.

It sometimes happens, if the weather is cold and damp, that roses are mildewed when taken up for housing. ' If the above directions in airing are attended to, and a little fire heat put on in the day in damp weather, it will soon disappear. If it should show itself any time afterwards, put on a little extra heat, and admit air from the top freely on sunny days, but keep the house closely shut up in stormy, and dull damp weather. By following this advice nobody need suffer from mildew when forcing roses. When, in the autumn, the nights begin to be cold, a little fire will be regularly required, increasing it gradually as the cold increases, observing to keep the temperature throughout the season at about 55° at night, allowing it to rise with the sun's rays to 70° or 75°, but not more than 60° in dull weather. Never use more artificial heat than is absolutely necessary. When the soil has become somewhat impoverished, say the middle of January, commence giving a watering with liquid guano, and continue it once a week, using one always applying either in a clear state. This will wonderfully improve the color of the flowers, and invigorate the plants.

The red spider (Acarus,) which is sure to make its appearance, and will destroy all success if not kept down, may he eradicated by syringing occasionally with a solution of whale-oil soap, using one ounce to two gallons of water. Be careful to apply the wash to the under side of the leaves, as it is there mostly, where the pest lodges - using it in the evening, after a bright day, as too much moisture in the atmosphere is apt to spoil the flowers. The green fly (Aphides,) is easily kept under by occasionally fumigating with tobacco. No further care is required.

By following the above directions, any person with from twenty to thirty good strong plants, may gather a boquet of Roses every morning from the beginning of November to the latter end of May, previous to, and after which, there are plenty out of doors. A small green-house- well exposed to the sun, and a small plot of ground outside, will produce roses every day throughout the year.

The above short list is not a tithe of the roses suitable for forcing, but they are sorts which will bloom without intermission so long as the plants are kept healthy, and freely exposed to the sun's rays. There are also many which have larger and more double flowers than some of them, but those mentioned are of different and distinct colors, from white to dark crimson, (including yellow,) and are beautiful in the buds, which are much more prized than the flowers by many. Hoping the above short hints may be useful - I am yours most respectfully, Wm. Chorlton, gardener to J. G. Green, Esq.

Staten Island, August 25,1851.