Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Plasticulture strawberries should have had nitrogen applications already, prior to bloom. Addition of 3-5 lbs of nitrogen per acre per week may be warranted. Nitrogen is critical prior to and during early bloom. Including potassium at a 1:1 or 1:2 ratio with nitrogen will often improve fruit quality (sugars). Use of tissue testing throughout the strawberry season is recommended to monitor nitrogen and potassium levels. Targets are 500 ppm petiole sap nitrate and 2500 ppm petiole sap potassium. Additional calcium may be needed as the season progresses.