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.
Owing to the great diversity of climate and soils in this country, it is beyond my power to give advice applicable to gardens generally, as there are some species and varieties of fruits which thrive admirably in one locality and yet fail completely in another, the treatment being similar in each case. The Apricot, perhaps, is the most fickle of the species. Not merely does it vary in different counties; but I have known instances where it has proved profitable, while in other gardens in the same parish, under ordinary treatment, it cannot be induced to grow to a serviceable size. It would appear to be most "at home" in the Midlands, notably Leicestershire and some parts of Derbyshire. There it may be seen growing on the cottagers' houses as freely as do Plums and Grape - vines in more southern localities; and as Apricots are very delicious, they are, as a matter of course, of a greater marketable value than either Plums or open-air Grapes.
It is useless to attempt growing Apricots on a strong clayey loam, and in gardens where this naturally abounds, it is absolutely necessary to excavate the border to a depth of 3 or 4 feet, to drain well, and refill with a much lighter compost, employing as much turf cut from a light soil as possible. This was performed here many years ago, and the Apricots have well repaid the outlay. In a large garden near here, where this has not been carried out, the trees in a short time invariably fail. Where the soil is naturally sandy and open, but little preparation is needed, though it is advisable to drain and to trench the ground. But little manure should be employed for the young trees, as a too free use of this induces an objectionable coarseness of growth. When in full bearing, or if the trees appear impoverished, freely fork in manure in the autumn or early winter, and mulch heavily in the spring. No particular site is necessary, at least in the more southern counties. Competent authorities recommend a south aspect for the Apricot in the more northern parts of Great Britain, and somewhat cooler sites in the more southern districts.
Here, for instance, there are strong fruitful trees growing against walls of west, south-east, and south aspects; those in the last situation being most profitable, simply because the trees have the benefit of protection by glass copings and curtains. (These copings are of great service, and soon repay for original outlay. Sharp span-roofed houses, on Dr Newington's model, would, if water was abundant, be always preferred, however, not only for Apricots, but also for Peaches, Nectarines, Plums, and Cherries.) A hot and dry position is really unfavourable to the production of extra-good fruit, as they are liable to ripen prematurely and unevenly, the quality being inferior accordingly. Where this is found to be the case, the roots should be heavily mulched with manure in May; receive copious waterings during the prevalence of dry weather; and if a fish-net doubled, or blinds of canvas, frigi-domo or other shading material, be hung over the trees when bright sunshine prevails at ripening time, it will equalise the ripening of the fruit - that is to say, it will be less likely to mellow on the side most exposed to the sun while yet hard on that next the wall.
Some of the most luscious fruit I have yet tasted were ripened under Russian mats, which were hung over, but at a good distance from, the trees, to retard ripening.
During September and early in October the planting of Apricots is best performed, and before they have shed their foliage, as they will then form fresh rootlets, and to a certain extent be recovered for a good start in the following spring. The varieties recommended for the country generally are Early Moorpark, Large Early, Hemskirk, and Moorpark. Apricots, more especially the Moorpark, after active growth has commenced, are liable to suddenly lose large branches, to the extent, frequently, of fully one-quarter of the tree. This is very discouraging, the more so seeing how superior, according to my experience, the fruit of the Moorpark are to other varieties. According to one of our highest pomological authorities, this arises "from injuries received by frost either in spring or early summer, or in winter after a wet autumn, when the wood has not properly ripened." As I understand it, neither solution is scarcely correct. We have lost a large main branch of a tree of Moorpark, and it certainly was not injured by frost in the spring, as the tree was well protected, and the sound part perfected a crop of excellent fruit.
It was the old wood evidently that first collapsed, and this we would suppose to be but little affected by a wet autumn; and I fail to see how the latter theory stands good, unless, indeed, the branch was imperfectly ripened when laid in about eight years since. The disease, to my thinking, is still a mystery.