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.
If a good dressing of manure be applied when the land is dug, it is all that is necessary, though a dressing of superphosphate or bone compound certainly helps to produce better flowers. This is usually applied at planting-time, just a small handful scattered round the hole; it is then mixed in during the actual planting. Liquid manure during the summer months would be helpful but it would not pay commercially.