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.
Much has been written in the pages of 'The Gardener' these two or three years about the Peach, a good deal of which has been rather conflicting: one recommends a night temperature not exceeding 45° to start with; and I have observed the writer of the Calendar recommends starting at 50°, and the same writer recommends syringing with water at a temperature of 80°. When I find rain falling in March at a temperature of 80°, I may be induced to adopt this practice. A third, the worthy Mr Simpson of Wortley, recommends the free use of the syringe when the trees are in bloom. Mr S. is somewhat given to startling ideas, and I must say I admire his progressive notions, although I have not observed anything new among them. All the above recommendations might be harmless under certain circumstances, while under other circumstances they might be hurtful, to say the least; and what might be pursued with safety in Mr Simpson's well-appointed structures, might involve considerable loss where Peaches are grown under difficulties.
For instance, if some tyro of an evening in February acts on Mr Simpson's advice, syringes his Peach-blossom freely at shutting time, having no adequate command of heat, and two or three gloomy days follow in succession, with a raw hoary air outside, such as we experience here at the present moment, I need not ask any gardener who knows how to grow Peaches what the result would be to the blossom, while it might be no injury whatever to the trees. In the same manner, some varieties of Peaches might be started with impunity at a night temperature of 50°; but if first-class Peaches are wanted, they will do better between 40° and 45°. When above the latter degree, I have always a little ventilation on, if the weather is such as to admit of it. I have something more to say about the Peach that may occupy another paper: meantime, with the worthy Editor's permission, I will proceed to draw attention to some more of what has been advanced of late. It appears, from an article by J. S. in your December number of ' The Gardener,' that our employers may congratulate themselves. According to the opinion of J. S., as far as the forcing of Muscat Vines and Peaches is concerned, we may haul out our boilers and pipes.
What a blessing when iron is so high in price, and coals so difficult to obtain at any price ! Young lads need not disturb themselves any longer waiting up of nights attending the fires, and masters may take matters easy, and then go to bed; no use for your nocturnal rounds to see how the stokers are doing their duty. Your Muscat-houses will do well if the temperature oscillates between 100° at mid-day, and 50°, or even 45°, at sunrise. This is what I call " gardening made easy," if it were not that it bears an absurdity on the face of it. I am not one of those who think the thermometer should not vary more than a degree or two in a night. Indeed, if the outside air is intensely cold, I think it is great folly to keep the heat up to a given point by excessive firing. But I may say here that Mr Shiels, late gardener to Lord Blantyre, allowed his young men only 2° to come and go upon. Some may think this sailing rather near the wind, but I can tell them that few gardeners have been more successful than Mr Shiels. I may say he had ripe Cherries for years in succession before there were any in Covent Garden; and other forced fruits were equally well done under his charge. But if the latter sailed near the wind, I fear J. S. is going to let his craft adrift altogether.
A difference of 55° in six hours ! If J. S. can point out a Yine-growing spot under the sun where the temperature varies as much in the 24 hours in ordinary circumstances, I will have no hesitation in supposing his system correct. The next proposition we may look for, will be to grow Vines on the open walls in Caithness-shire. Your correspondent says he has proved that Muscats will set like Peas in a temperature of 60°. I question this; but even though we allow this, we have often seen Muscats set that never stoned, and there is a vast difference between 60° and 45°. A dewing with the syringe might be a nice thing for them at the latter figure. Now, we believe success depends on assisting nature, not in departing from natural laws. We most unhesitatingly approve of a low night temperature for Peaches; but Vines are quite a different thing. The Peach flowers, sets, and stones on the open wall when the night temperature is all but freezing. What would the Vines do under the same circumstances 1 Nothing but remain dormant; and when they do begin to move, they will require about ten weeks growing under ordinary circumstances before they flower.
Hence, when our Vines are fairly started, we believe in the scale of temperature recommended since ever we saw a Vine, and still recommended by that most eminent of growers (in his 'Treatise on the Vine'), our Editor's brother, of the now deservedly-famed Tweed Vineyard; and, notwithstanding all this, our leaves and shoots present the very picture J. S. describes as existing in a house without fire-heat in the morning - namely, the leaves are laden with globules of water, and the shoots bursting with vigour, and dotted over thickly with gelatinous superabundant sap. Moreover, we never have such a symptom as untimely withering of the foliage. We rather pride ourselves in maintaining our foliage until it turns a beautiful pale yellow - beautiful because it speaks of finished eyes and well-ripened wood. 1 may add here (for the benefit of those who may not possess the means of obtaining the information), on the authority of the late Mr Thompson, of Chiswick, who went very carefully into this subject, and took his data from nature as much as from science, that the mean temperature of Beyrout, Cadiz, and Catania, (while Vines are in flower), is respectively 69°, 63°, and 71°. At the latter place, the Muscat of Alexandria attains a high degree of perfection in the open air under the name of Zebibo. This speaks volumes.
Your correspondent J. S. is inclined to think that many of the pests that infest forcing structures are traceable to fire-heat; spider and thrip he especially points out. I beg to ask him what we are to blame for those plots of Gooseberries in the open gardens that are frequently to be seen denuded of their leaves with red-spider? I have no hesitation in saying that if the proper atmosphere is maintained in a forcing-house, such pests will not give much trouble. I meant to have described an effectual mode of destroying spider in vineries, but perhaps, as I have drawn this out sufficiently long, I may, with the Editor's permission, make it the subject of another paper. This paper has been written with no other object than the arraying of facts against such chimerical ideas as those advanced by J. S., and suchlike; and I am just as ready to return to the subject as J. S. is, and give him facts for a lifetime, if I think it worth my while. D. J.