I told you in my last letter that the director of the garden of Villa Traversi, in Desio, multiplied his roses by grafting on the root; and now I can tell you of its further extension, as it is practised by me not only on the rose, but also on the olive, berberis, cytisus, crataegus, &c. Wishing to graft in January and February (the most proper time), I take up the roots intended to be used for this purpose in November, because in January and February it would be difficult to do so, on account of the frost; and having put them in a corner of the frigidario, deep in the ground, care being taken that they do not germinate, I then leave them till the moment I wish to make use of them; and, when that time comes, I choose some healthy roots, that is, those without any defects, and about the size of a quill, or the little finger. I then cut them of the length of from 3 in. to 5 in., and make a vertical cut, and proceed as with split-grafting. I then plant them in pots of about 3 in. in diameter. As soon as they are planted, I cover them with a pane of glass, and put them in frames, or in the pine-stove; and, as soon as I see them beginning to grow, I give them air by degrees, and in a few days I take off the glass entirely, and allow them to enjoy the rays of the sun, which should also be done from the first day of grafting. By this process I have been enabled to graft from January to the end of July; and, in summer, I only use those roots of the rose that I think will not injure the plant, which must furnish roots to be again grafted the following year. The roots of the Chinese rose, and those of R. multiflora, are to be preferred, because, from what I have observed, they do not put out buds below the grafting, as is the case with Rosa canina, &c.; and by this means, in two months, plants will be formed, and produce flowers, particularly the variety of Rosa odoratissima. This kind of grafting is, in my opinion, preferable to the other, because the latter is not always successful, and requires a great deal of care, and as many as are wanted cannot always be obtained. The failure is only about ten in a hundred; and, from the observations that I and others have made on those that failed, I am convinced it was from the bad selection of the grafts, because they require to have good and healthy buds; and it is essential to choose vigorous shoots, that are neither tender nor immature, and that have two buds well nourished and formed. When I wish to graft anything in summer, when the plants are in full vegetation, as soon as I have fixed on the one that I wish to have grafted, I take of the extreme point of the branch that is to be the graft, and when I see the buds growing large I cut it of and graft it. This method of grafting has the advantage of not having the protuberance which is seen in plants split-grafted or by application, which amounts to a deformity, produces decay, and then death; whereas, by root-grafting, only one wound is seen, well closed, and, from its proximity to the ground, in all probability when it is transplanted it will have the advantage of being put a little below it, so that the graft itself may put out roots, as I have already observed in several of them. I have seen a paper by M. Poiteau, in his Revue Horticultural, on this method of grafting; also, perhaps, in the Annales de la Société Hort. de Paris; but the putting it in practice in summer is new, and that is the time when plants are in their full vigour. — Giuseppe Manetti.
[The foregoing communication was unfortunately mislaid after the essence of it had been used in the Arboretum Britannicum. On this account we entreat our correspondent and our readers to pardon the seeming neglect. We have now, we believe, inserted all the communications which we have ever received from Signore Manetti, and we hope he will be encouraged to continue them; for we are certain that all those of our readers whose taste rises higher than mere culture, who have, in fact, elegant minds, will read them with pleasure as well as with instruction.— Cond.]