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.
Several cases of the failure of Peach crops in unheated houses have come under our notice this season. Considering the very sunless summer, and especially autumn, of 1872, in a great many districts such a failure is just what might have been predicted; and any gardener who had it not in his power to apply artificial heat to his Peach-trees in the October of 1872, cannot reasonably be blamed for the want of fruit this year. Under such circumstances, the fruit-buds never get properly developed, nor the wood ripened. The foliage clung to the trees unnaturally late; and when the time of blossoming arrived, not only were the blooms and their sexual organs weak, but the whole trees were in such a condition that the blooms were thrown entirely off before they set. This result is none the less likely to occur to Peaches in spring, on account of their being enclosed in a glass case, but the reverse. Hence in some cases there were outdoor crops, while in unheated cases there were none or next to none.
Trees under glass are, from the effects of bright suns, more likely to be excited at a pace which outdoor trees are not subject to; and the more violent the flow of sap, the wood-buds are more likely to take the flow and start into growth, while as a consequence, and at the same time, the flower-buds are actually thrown off altogether, and the crops are thus lost. In the northern parts of England and Scotland, where there are less chances of thorough ripening, late Peach-cases should have some means of being artificially warmed, in order to ripen the wood in such autumns as 1872, and of this year also, when we have had such sunless and wet seasons. It does not matter how healthy the trees may be; no power at the command of the gardener can insure a crop if the buds and wood are not, to say the least, moderately well ripened. We saw several houses near the very centre of England where strong-growing Peach-trees had not produced any fruit, and from no other cause than that of the want of applying, or having the power to apply, fire-heat to ripen the wood and " plump up " the buds.
And after the very sunless and wet season we have this year experienced over a great breadth of the kingdom, if like results follow, employers should not blame their gardeners unless it be where they have the means of firing the trees in autumn and have neglected to do so. Peach-cases should all be heated, to enable gardeners to cope with the effects of a dull season in the case of the Peach crop, as well as render such structures available for wintering half-hardy plants, in many cases where such accommodation is of the worst description.