POINSETTIA pot plants must be grown under relatively moist conditions and with a relatively high supply of nutrients to produce a quality flower. Growers start plants in July or August for sale during the Christmas season. During this four- or five-month period, the plants may be irrigated with as much as 100 inches of water, making the maintenance of fertility levels difficult. Irrigation water is sometimes used to maintain fertility, but not all growers have liquid fertilizer equipment. Newly developed slow-release fertilizers are especially adaptable for high value ornamental crops, such as poinsettias, to provide the mineral nutrients over a prolonged period of time.

Sunnyside Nursery of of Hayward and Breitner Nursery of Colma cooperated in this research.