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.
"A Subscriber" in last month's ' Gardener' wishes for information as to propagating the Mulberry; and why cuttings, which were taken from a fruit-bearing tree, and struck thirty or forty years ago, do not yet carry fruit, although they are now vigorous young trees.
The fact of their being so vigorous and healthy, no doubt, accounts in part for their unfruitfulness, and is probably the result of the cuttings having been taken from gross unfruitful branches near the ground or from suckers; and when plants are raised from these they are very little, if any, better than seedlings, which, like those of the "Walnut, seldom perfect much fruit before they are forty years of age. The best cuttings are those taken from the most productive branches, near the top, and on the south side of the tree. If such branches have not been noted while in fruit, the next best criterion is a short-jointed and twiggy habit: from these take cuttings in the beginning of March, 6 or 8 inches in length, of the previous year's wood, with a joint of two-year-old wood at the base; insert them round the sides of well-drained pots, and plunge in mild bottom-heat, failing which, they will strike almost equally as well in a shady border, though not so speedily. Many years may be gained, however, by adopting the rough-and-ready plan of striking whole branches, the thickness of an ordinary walking-stick. They should be taken off before the sap begins to move, otherwise the tree is apt to bleed excessively, trimmed into shape by pruning off the straggling twigs, and planted 18 inches or 2 feet deep.
In very dry weather they will require plenty of water; and in due time these adult-cuttings will push away as if nothing had happened.
Grown in pots, and receiving similar treatment, the Mulberry (M. nigra) can be fruited at as early an age as the Peach. P. D. T.
I hardly think the reply of E. T. D. meets the requirement of "a Subscriber" in a former number of the 'Gardener.' Most trees planted in soil above their natural requirements throw down a deep or tap root; and when such is the case, the tree runs into excessive growth, and becomes unfruitful; and I believe there is no remedy for this other than that of undermining the tree and severing the tap-root. This gives some trouble, but it is difficult to kill the Mulberry. The "lane I live in," until covered with houses, was celebrated for the Mulberry. There are two or three feet of light soil, then eight or ten feet of sand and stony gravel, affording perfect natural drainage. In this the Mulberry thrives and fruits. In the Hector's garden there exist the venerable remains of a Mulberry-tree, of unknown age. In my own garden there was a Mulberry of apparently equal date; it was called Queen Elizabeth's Mulberry - the garden having been a part of the domain of Catharine Parr, sixth wife of Henry the Eighth, and tradition fixed the planting of the tree on the "Virgin Queen." I have a very fine Mulberry, planted 35 years ago, which never fully bears, having been planted where the gravel has been dug out; it has run to excessive growth, and fails in bearing fruit.
A 'Subscriber ' in the ' Gardener' for January (page 48) wishes for some information respecting the propagation of the Mulberry, and how to increase its fruit-bearing habits at any earlier age than usual. Perhaps the following observations on its culture may be of use to him and others who have had no experience in raising plants for the early fruiting of this very rich and desirable fruit for the dessert. When I first came to Welbeck in 1837, I was much struck with some large flower-pots perched on the tops of two standard Mulberry-trees, and imagined they were placed there for some species of birds to build their nests in. On asking the late Mr Mearns (who was my predecessor as gardener there), he informed me that the late Andrew Knight of Downton Castle always used to raise his fruiting-trees of Mulberries in that way. Mr Mearns likewise informed me that Mr Knight found out that, by propagating the Mulberry in the usual way, it required from twenty to thirty years' growth before it would fruit abundantly even in the south of England. I paid particular attention to these little Mulberry-bushes, and, when perfectly rooted, had two of them in a fruiting state for many years, by shifting them, and growing them in large tubs.
Mr Mearns's trees were propagated by layering a small fruiting-branch into the pot, and the pot afterwards fastened with strong wire to a branch or stake to keep the wind from shaking it. I believe the best way to produce a large fruiting-bush of the Mulberry would be to have a large flower-pot made into two halves, and when the branch was put in at the hole in the bottom of the pot, the pot could then be bound together and fastened to a strong stake; the pot would then have to be filled with earth of a strong loamy nature, and some fresh moss placed on the top and pegged down to keep the wind from blowing it off. This moss would keep the soil moist, for watering would be required in the summer months in dry weather.
In the midland counties in England it is only in exceptionally warm summers, such as 1846, '65, and '68, that standard Mulberries produce fruit ripe enough to use. The two standard trees from which the pot bushes were raised were planted by the celebrated Speechley, and must have been about 110 years old when I first knew them. Another tree of the same age was denuded of all its branches by Mr Mearns (except two at the top), and planted on a high south wall. He began training all the young branches downwards from the two leaders, and they soon got into a fruitful state, and produced fine fruit. No doubt a sunken pit where Asparagus was forced in helped this tree's growth, for its roots came close to the wall where the hot dung-linings were put in. In 1858, when the new gardens were made, I had this tree lifted with a machine, and planted in nearly a similar aspect, but without the advantage of its roots being heated in spring. Every year since it has never failed in bearing fine fruit, but in the past summer they were larger and finer than I ever remember to have seen Mulberry fruit even in the south of England. The tree covers a large space, and was worthy of being covered with Nottingham netting, which I had to do to save the fruit from birds, wasps, and flies.