Ventilation can begin during the day at 75 degree F. Slightly warmer or cooler temperatures can be used to speed or slow the crop, but extremely higher or lower temperatures will delay finish. Elongation of the flower stalk is sensitive to positive or negative DIF either applied generally or as an early morning application. Relative Humidity Botrytis can be a serious problem with gerberas during dark, cool periods in winter when the greenhouse humidity is high. Take steps to keep the humidity below 70 percent during the day and below 85 percent at night. Good internal air circulation in the greenhouse at night and ventilation during the day are essential.
High humidity appears to contribute to flower stalk stretching.
Light Gerberas require high light intensities for good-quality plants and high flower bud numbers. For this reason, they are mostly produced in the spring and summer, with the greatest amount of production for the spring market. Plants grow best in full sun during the fall, winter, and spring. Plants receiving too little light have pale green, stretched foliage and long, weak flower stems. Plants receiving too much light have compact, slightly yellow foliage with short flower stems often hidden in the foliage.