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.
For the final potting, 16's (9 in.) and 12's (10 in.) pots are used, about 1 in. of crocks being laid over the holes. First place soil in the bottom, ramming it firmly, then put the plant on top, placing it at such a depth that the top will be covered ½ in., and the surface of the soil 1½ in. from the top of the pot. Then it should be filled up gradually, an even degree of pressure being maintained. Firm potting is most essential, and it must be even throughout. It is as well to have some straw or canvas handy in case of frosts, which are not unknown in June. No water should be given till the plants show signs of flagging, when a good soaking will be best for them. If the plants are potted properly, when the pots are filled to the brim the water should take two or three minutes to soak away.