This section is from the book "The Gardener V3", 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.
This subject has received considerable attention from cultivators of late. Various modes have been tried to improve the Vine by grafting, and the results, favourable and otherwise, have been reported in the different Gardening periodicals from time to time.
It has been proved that some Vines bear much better when grafted on a different stock than when growing on their own roots j that grafting has been the means, to a certain extent, of preventing varieties subject to cracking and shanking from doing so; and that the fruit is considerably improved in size and quality.
My object in writing is not so much to speak of the results of grafting as of the practice of grafting itself. Loudon in his ' Encyclopaedia of Gardening' describes a great many methods of grafting the Vine, and quotes his authors on the subject. Others have written their experience on the subject since, but none of them differing much from what is to be found in Loudon's works. Budding has been successfully performed by some; but inarching and grafting are the modes generally practised.
There is not much difficulty in grafting the Vine by any of the ordinary methods, but one of the best we have seen is that practised by Mr Johnston of Terreagles Gardens, near Dumfries. Mr Johnston has been a zealous and successful cultivator of the Vine for more than thirty years, and has experimented a great deal upon it. He has tried every method of grafting known, and has come to the conclusion that for Vines there is no better method than that which he has practised for a number of years with every success, and which he has very properly termed "Dovetail grafting" (fig. 10). It is simple, as well as sure, and fruit can be obtained from the graft the first year after its insertion.
The grafting is performed in the following manner, and before the sap is in motion. The stock may be of one year's growth, or more; but young wood from one to four years old is preferable. The place selected for inserting the graft should be opposite a bud, or spur, with one or more buds to draw the flow of sap to the scion, which also prevents bleeding. Having selected the stock, the wood should be cut out of it from 2 to 2 1/2 inches in length to a depth corresponding to the thickness of the scion, in the same manner as dovetailing in carpentry is performed. The scion is then prepared by being cut into the pith, leaving the bud in the middle, and made to fit neatly into the stock, after which it is firmly tied with matting and clayed over, leaving a small hole opposite the bud, so as not to obstruct its growth. A little moss is then tied over all, and kept moist for some time till the bud begins to grow. After it has grown some length, the opposite shoots are shortened, and eventually taken off altogether.
Mr Johnston informed us that he has grafted old stunted wood in the above way, where the wood was bare; but in cases of grafting, young wood is to be preferred. A. Pettigrew.
[We have practised this mode of grafting, and can endorse what Mr Pettigrew says of it. - Ed].