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.
Where pot roots or division of the old stools are relied upon for the stock they should be planted out in April, but it is not advisable to plant out young green plants until the first week in June, except in sheltered places or in the South. It is advisable, where the plants require staking, to drive the stakes before putting in the plant. The strong-growing types, such as Cactus, Show and Fancy, Paeony-flowered, and Giant Decorative should have one central stake and four outer stakes; this leaves room for vigorous growth. This will apply also to many of the tall-growing single, Pompon, and Decorative varieties. The outer stakes can be put in as the plant requires them. This staking is all-important where large flowers are required, for where a single stake only is employed the plants have to be tied in like a faggot, which effectually prevents half the growth maturing sufficiently to flower. Where the plants are only required for stock purposes it is not necessary to go to the expense of stakes; they can be planted more thickly and simply cover the ground. The grower must check each plant while in flower, to see that all the stock is true to name. All the strong-growing varieties should be allowed at least 4 ft. between and in the rows. The Pompons, single, and other shorter types can be grown at 3 ft. apart each way.