Several growers have called to tell us that they have many blind shoots this year. What are the possible causes: - 1. The hydrangea last fall should have had about six weeks of night temperature below 65°F. and preferably not below 40°F. 2. Heavy frost caused premature leaf drop. 3. Heavy infestation of mildew which reduced effective production of stored food. 4. Plants may have been stored too early. 5. Plants may have been pinched too late last summer which did not allow enough time for proper plant growth. To obtain good blue color in hydrangeas do not use fertilizers containing phosphate and maintain pH at 4.5 - 5.5. Suggest using 20-0-30 or one of similar analysis.
Source: • Florogram March & April