This section is from the book "The Gardener V1", 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.
Had we time to attend as systematically to the roots as to the pruning and training of the branches, good crops of fruit - putting accidents of weather, etc, aside - might be calculated upon to a certainty; but it is seldom, indeed, that the gardener has the means of accomplishing all that he knows to be necessary in this respect.
But let us look more particularly at the objections themselves which have been raised by different writers to cropping the borders, and see what real weight is attached to them. There are only two of importance. The first is, that the roots of the fruit-trees are mutilated by the spade in digging the border; and the second, that they suffer injuriously from cold in winter, and heat and drought in summer. The first objection may be disposed of by saying that, when digging is done regularly, the tearing and cutting asunder is a myth, as every experienced gardener knows: in scores of instances, I never saw as many roots brought up with the spade as would fill a tobacco-box, in borders hundreds of feet in length. And as to the second objection, I would ask how could the roots suffer to any extent, either from cold or heat, a foot beneath the surface of a well-pulverised border, shaded by crops - the very conditions favourable to the retention of moisture in summer and heat in winter? True, the vegetables absorb a certain amount of moisture from the soil, but they make up for it by the shade they afford; and the manure which is annually applied, by keeping the border open, acts to a great extent as a mulching.
But even supposing the roots were subjected to extremes of heat and cold, they would soon acquire a certain degree of hardiness that would enable them to resist either within ordinary limits. We have constant experience of this, and it is a fact which I do not think is questioned. Surface-roots are always of a much hardier constitution than those which penetrate deeply into the soil. We can readily believe that if a Strawberry plant, which had rooted deeply into the soil, was lifted, put in a pot, and exposed to severe frost, it would die, or at least be greatly injured; but such would not be the case with a plant that had been grown in a pot, because the roots would be hardened by exposure. By many, frost is supposed to be fatally injurious to the roots of strawberries in pots; but there is really no cause for apprehension on that point, provided the plants are kept dry and not thawed too rapidly. I have seen pot-plants exposed for a long period to from 12° to 15° of frost - until the balls of the plants were raised about an inch above the rim of the pots - and afterwards bear an excellent crop of fruit, the roots not appearing to be at all affected.
Indeed, it has yet to be proved that the roots of fruit-trees - such as pyramids - when regularly root-pruned, and encouraged to root near the surface, will not resist as much cold as the branches. I have certainly seen Pear-trees under these conditions bear excellent crops of fruit after a severe winter, during which the roots of the trees must have been a frozen mass for weeks at a time. During the severe winter of 1866-67 a lot of growing pyramids here, which had been lifted the winter previous, were in this plight, as many others must have been throughout the country; yet those which escaped late frosts bore good crops - nor had the roots suffered any apparent damage. Facts such as these, which are no doubt common to the experience of most gardeners, warrant us, I think, in concluding that we have no reason to apprehend danger to the roots from frost that will not injure the branches or buds while in a dormant condition. Nevertheless, I would not advise any one to neglect mulching or other means of protection when they can afford it.
But to return to the border-cropping, and to add our testimony to that which has already been furnished by able and experienced gardeners in favour of continuing the system, we may state that we have an Apricot and a Plum wall here, the border of which, until about three years ago, had, as the writer I have quoted reverently puts it, been "sacred to roots" - having been planted with Roses, as the wall happens to face into the pleasure-grounds. Farther than receiving an annual top-dressing, the border, as far as I am aware, had not been disturbed for many years; and although the trees are pretty old, and do not appear to have been neglected in the training, their success never was such as would lead any one to think that the non-cropping system had any particular advantages. About three years ago, however, the Roses were lifted and the border was dug resolutely a spade-depth all over to within 4 feet of the steins of the trees, and since then it has been regularly planted with bedding-plants; and I can state confidently that down to this date the trees are at least no worse, but better - in so far as the growth has been more vigorous, and the crops better.
The year before last the Apricots bore a moderate crop, and last year quite an extraordinary one - such as history, at least, does not credit them with before. The Plums, though healthy, have not borne so well, but want root-prunning. We have another inner south wall planted with Pears. Though old, and now somewhat lengthy in the spur, they are perhaps as fine specimens of horizontal training as could be found, generally in good health, and seldom failing to bear heavy crops of fruit; in fact, we rely upon them chiefly. Yet the border is, and has always been, cropped regularly once or twice a-year, and towards the front is sometimes dug a spade and a half deep, without injuring the roots in the least; and I should think they have had ample time to hoist their signals of distress if the practice disagreed with them. There is another wall of Jargonelles here, equally fine specimens of fair training, but in too rampant health, in spite of constantly cropped borders, as the subsoil under them is a deep strong clayey loam, which the roots persist in getting down into with a perseverance that "is well-nigh miraculous" - prompted, I suppose, by a sagacious instinct to escape the "barbarous mutilations" of our "ruthless spades".
We have no Peaches outside; but the outside half of the border of our early and late Peach-houses is cropped regularly without any apparent bad effects. We even carry the cropping on to our Vine borders. In one case - a late Hambro'-house, referred to by the "Squire's Gardener "in the January number of the 'Gardener' - where the roots are almost entirely outside, the border is cropped annually with early Potatoes and suchlike, and seemingly the annual manuring for the vegetable crops has the best effects on the Vines also. The crops are always heavy and well finished. We have cut 3 and 4 lb. bunches out of the house, and prize Grapes not unfrequently. In digging the border, the roots of the Vines are never seen, but just beyond the reach of the spade they are to be found in quantity.
Instances like the above could, I have no doubt, be furnished by many of your readers. Economy has to be studied in gardening nowadays quite as much as in other things; and as the value of border-crops is often not far short of the value of the fruit from the walls and houses, I think most gardeners and proprietors will pause before adopting a system which has neither utility nor practical evidence to recommend it. J. Simpson, Wortley.