This section is from the book "The Gardener V2", 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.
Although orchard-trees, at least when on a good, deep soil, and in a favourable locality, certainly give the greatest amount of fruit for the least possible trouble, it is not every cottager or villa-owner who can afford space for them, or has patience enough to wait many years until full crops are produced. Medium-sized trees - that is, trees grafted on the Crab Apple or English Paradise - may be grown in less space than ordinary orchard-trees : they come earlier into bearing, and, as they are planted very much closer together, sooner attain their full growth and yield a full crop from off a given piece of ground. As a set-off against this, such trees, to do them justice, require to be systematically pruned both at root and top. On peculiarly favourable soils and in favourable localities they may be treated on the let-alone system to a very great extent, but on ordinary soil and in ordinary situations systematic cultivation will be required to produce satisfactory results. We have seen such trees on a moderately deep soil, on a whinstone bottom, do first-rate without anything being done to them at all, except the occasional removal of a crowding branch, and a little cow-urine at the root in winter.
We have seen the same kind of trees on a thin soil, with a cold, damp, clayey bottom, which for years did no good at all in the way of fruit-bearing, although the annual growth was strong and healthy; and after these trees were carefully lifted, root-pruned, and planted again with their roots placed near the surface among open soil raised a little above the surrounding level, and mulched with manure, they produced splendid crops for years afterwards. The reader will understand by this that what may be proper on one soil and in one locality, may be highly improper on another soil and in another locality. When trees which are planted on a strong soil of average fertility, with a dry wholesome bottom, make a fairly good annual growth, and after three or four years begin to bear fruit of a good quality freely, it will be wise to let the roots alone. On such soils, especially if poor, it is just possible that fruit may be too freely produced, at the expense of the annual growth - so much so, that the trees make no headway. We have found that a good mulching of manure over the roots, coupled with a soaking of manure-water once in May, and again in June or July, had a very good effect in producing free growth and fine fruit.
An indispensable factor in the production of good fruit and healthy growth are fibry roots near the surface. The Paradise stock and, in a lesser but still fairly good degree, the Crab produce good fibry roots naturally on dry stony soils, and mulching draws them towards the surface and keeps them there. The roots go where the sap and the food are, and it is a good thing to keep the food and moisture at the surface. Digging in manure is not a good way to secure this, because rank manure, when the roots can reach it, causes the formation of strong sappy roots; and such roots produce strong sappy wood which is not fruitful, but the reverse. Moreover, every drop of rain that passes through manure so placed, carries its essence deep down, and the roots follow. Again, manure dug in does not promote moisture at the surface in dry weather; and so there is nothing to attract the roots thither. Mulching, on the other hand, promotes moisture at the surface; and as the rain carries the strength of the manure into the soil, the roots get the benefit of it, just as much as if it were dug in. Practical men thoroughly understand all this; beginners seem not to do so, - at least in many instances which have come under our notice.
The untidy appearance is sometimes objected to, especially when the garden adjoins the house. An inch of fine soil placed over the mulch makes everything tidy.
On deep, damp, rich soils, such trees generally grow very strongly, but do not fruit well. It is these trees which require the systematic root and top pruning to which we referred. Trees on the Paradise or Crab stock which produce a profusion of shoots a foot and a half or two feet long, and few flower-buds, which results in puny fruit, need root-pruning. While the trees are young this is an easy job; and on such soils as we have just named, the roots of the trees should be taken in hand and kept right from the first. The roots produced in rich soils are generally anything but fibry and near the surface, but by lifting and root-pruning them they may be made so. When this is done (October is the best time for doing it), all fibry roots should be carefully saved, and in planting kept well up. Strong clean roots should be well shortened in. The result of this will be a moderate fruitful growth above and a mass of fibry roots below. When the trees begin to fruit, the calls made on their energies will do much to keep down the tendency to over-luxuriant growth. Below, however, the roots will be apt to grow strongly, and so produce unfruitful growth. When this is so, root-pruning must again be resorted to.
When the trees attain some size, however, it may be wise to lift the roots of only one side of the tree one year, and the other the next. In the case of old, unfruitful, neglected trees, it is best to carefully find the strong roots, and, instead of cutting them back, lay them just under the surface. This operation is necessary to produce healthful trees, and to keep them healthy, on all thin soils with a bad subsoil. When the roots penetrate bad soil, diseased unhealthy trees are the result. Root-lifting is a sure cure - or rather a sure preventive.
A. H., H. (To be continued).