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.
It has often occurred to me, while observing the fruit trees growing on the walls of houses in many of the villages throughout England, especially in the southern districts, that the firmness of the soil has much to do with the longevity, hardiness, and fruitfulness of these trees, which are generally loaded with fruit of very fair quality. There is little attention given in the way of cultivation; all the training they get is a cut here and there to prevent the young branches from pulling the old ones from their fastening. They must have grown apace at some period, as large breadths of mason-work are covered with single trees, such as are not met with in many gardens. In this locality (Oxford) Apricots have been famous for many years, and great crops have been gathered; and the industrious villagers have often been able to pay their rents from the old trees on the ends of their houses. It has appeared to me in most cases that these veterans have been planted with very little care - probably a hole has been made, enough to twist the roots into, and the soil replaced over them, and rammed down as if to form part of a floor.
The hard-trodden gravel (in many cases causeway and pavement) would lead one to suppose that moisture could never reach the fibres, but I suppose the fibres must travel to the moisture; a wide street is generally the space where the border should be. Other trees have the usual outhouses standing over the space where the roots are supposed to find their food. It is evident there must be food, or where is such fine foliage and luscious fruit manufactured 1 Vines are met with often growing under the same circumstances: one on a tradesman's house in a town not far from here is something wonderful in its way - the kind is the black Esperione. I am told that it has produced heavy crops for many years past, and this year the bunches almost touch one another. There are only a few inches of open space between the pavement and base of the house front wall. The pavement and causeway together, between the Vine and the street, may be twelve feet wide, yet this Vine luxuriates, and supplies its owner with plenty of fruit, which is used generally for wine-making. Without discussing the matter further, is there anything we can learn from these trees, which are more productive of stronger constitution, and less liable to disease than the finest-trained trees under the care of some of our most distinguished gardeners 1 From experience, I believe that the firmness of the soil prevents over-luxuriant growth, inducing the roots to become a mass of healthy fibre, instead of their sending out large soft feeders, drawing up large quantities of water, which remains in the branches till the short dark days of winter.
No fruit buds are matured; the buds start early into growth long before they are safe from frost. The sap, which has been flowing freely, receives a check; nothing is seen at the time, but before summer has advanced very far, a large limb (perhaps the healthiest looking in the tree) dies off suddenly; it is cut out, other branches die off in the same way, and the poor tree is sadly deformed. Cases similar to this are met with all over the country, and yet we have found no preventive. One thing I would suggest to young planters is, - never accept a tree which has been often cut back in the nursery, or one which has not been properly cut. When pieces have been left, the branches are always liable to die back where these pieces have been attached. When the cut is clean and properly done, the bark will grow over, and the wound will heal up nicely. When planting is done, never use manure (except for mulching, to keep out frost or drought); let all the soil, after it has been prepared, be made as firm as a rammer can make it, - if stones are plentiful, so much the better; the soil may be placed over the roots, and made only moderately firm. Endeavour to get the tree to start freely, and use the knife only where it cannot be avoided.
When the roots have run a little, they will come in contact with the hard rammed soil, and will throw out fibre in all directions, which will cause the tree to grow sturdy, and the young wood will become very hard. When any shoot takes the lead, and is likely to monopolise the whole growth, take off a joint or two at top, and a number of small shoots will spring up; train them over the empty space, and the foundation of a sound tree will be formed. Avoid the use of the knife in winter if possible, and if root-pruning should become necessary, let it be done early in the autumn, - but examine the roots first at one side, taking off none except they may be going downwards, or away from heat and air, - replace the soil (or fresh loam instead), and ram it as hard as possible under the roots, and lay every fibre carefully in its place, and cover them over as before. A very small portion of the tree thus treated will be enough to check unnecessary growth, and large firm leaves, plenty of natural fruit-spurs, and a hardy tree, will be the reward.
The cutting round the whole tree with a spade, as some have done, is reckless and mischievous in the extreme.
If too rich soil should be the cause of watery growth, lift the tree and mix some lime rubbish in the earth; ram it down, and lay out the roots over it, and place 6 inches of loam over them. This should be done as the leaves are about to fall in autumn.
Speaking of the Vine, how often do we see promising young rods bear well for a few years, their roots filling the porous border. They begin to fall off: extra top-dressing is given, shanking goes on, red-spider destroys the foliage; yet all seems right at the roots. But careful examination will show that the feeders have found their way into a poor unhealthy subsoil, and as fast as fresh rootlets are made they die. The fine rich border is left behind, and all the manuring, watering, etc, is so much labour thrown away. The points of the roots are beyond help, so the vinery by degrees becomes a wreck. But if Asparagus-beds, or a free sound loam, is in the way of the roots, instead of unhealthy stuff, the Vines will not only remain healthy and vigorous, but be rejuvenated. The same applies to all trees, even to the Oak of the forest: a tree may grow luxuriantly for years, and at last begin to fail (hundreds around me are striking examples). If the cause was searched after, the active roots would be found far from the trunk, out of the reach of the famous loam which had made the gigantic tree, and struggling for an existence among material foreign to their nature.
We should never despise the lessons which old trees in cottagers' gardens teach us, but search out the cause of their success, and it will be found that the roots are in their natural element; and the roots of our own trees (which are growing at railway speed) are in unusually rich quarters, where they will luxuriate till they bring about their own destruction. M. Temple.