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.
No doubt this plant and its varied qualities are well known to the professional gardener, but I fear that amateurs know less about it as a forcing shrub. Let that be as it may, few of our hardy plants submit with more freedom to artificial heat, during the dreariest months of winter, with but a slight advance of temperature. Much as we admire the Lily of the Valley, the flowers of this plant are in no way inferior, are similar in shape and colour, of longer duration, and closely arranged on long racemes. Propagation is so easily managed that the merest tyro can have little to fear. This much, however, I may say, that half-ripened wood roots freely when subjected to a high bottom-heat. Subsequent treatment merely consists in having the nurslings put into small pots, hardened off, and ultimately transferred to the open ground. As old plants produce suckers freely, they may be divided ad libitum, and treated as young plants. But unless special circumstances require it, home propagation is scarcely necessary, as plants fit for forcing can always be purchased for a few pence. A flower is always produced on the preceding year's wood; the old shoots should be cut off close to the ground, and the plants then turned out. This will cause them to grow stronger than if kept in pots.
In addition, we have Deutzia scabra, scarcely inferior to gracilis, with the exception that it does not flower so abundantly. Still it deserves our special attention, and well repays our trouble.
Wherever flower-forcing is carried out to some considerable extent, a house with the convenience of bottom-heat should be specially set apart for this purpose, else less or more failures will certainly occur, traducing the gardener's abilities, and depriving the plant of its proper share of attention.
The general plan is to make use of early vineries, peach-houses, or any available space where a few spare feet can be spared - a reprehensible system, that cannot be too strongly discouraged, introducing among fine crops red-spider, green-fly, and a host of other pests. I am sure it would be a great advantage to many were some qualified person to give us an annotated list of shrubs best suited for forcing.
Alexander Cramb. Tortworth.
[Will Mr Cramb kindly favour us? - Ed].