This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
It will often be found that a variety will "run out", as it is termed. In the case of fancy varieties they revert to a whole colour, while many of the double and cactus forms appeal semi-double. This can always be corrected by buying in a new stock from a totally different soil, when not only will the flowers come true again but they will produce better stock for the following year. [J. B. R].