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.
A fine Mexican half-hardy annual, 1-2 ft. high, with ovate, stem-clasping leaves and single and double flower heads of various colours, such as scarlet, vermilion, crimson, carmine, rose, white, buff, yellow, etc. There are now many fine garden varieties, the result of careful selection and hybridization, the flower heads in many cases being beautifully symmetrical in shape. The dwarf Pompon or Lilliput varieties grow only from 6-12 in. high, and are very effective "bedders". Z. Haageana has brilliant-orange flower heads with single and double forms.
The Zinnias are raised from seed sown in February and March in the same way as the Ten-week Stocks and China Asters, and are sold in shallow boxes or pots in April, May, and June for bedding-out purposes. They are wonderfully effective when grown in rich soil in sunny situations (fig. 257).
Fig. 257. - Zinnia.