1. Use a fertilizer which contains Zn.
2. 1. Corrective drench application of zinc sulfate at 13.9 ppm of Zn for soilless substrates. A corrective fertilization of Zn will return the tissue to a normal green color within 1 to 2 weeks. Add 0.5 oz. (14.2 g) of zinc sulfate (36% Zn) per 100 gallons of water. Do not over apply. Rinse off foliage.
3. To apply a foliar spray of Zn: mix 2 oz. (56.7 g) of zinc sulfate per 100 gallons of water. It will give a final concentration of 56 ppm Zn. Test on a few plants first. Do not over apply.

Foliar sprays have a greater risk of plant injury. Avoid applications during the midday heat. Plant uptake is enhanced by prolonged drying time, which occurs during humid conditions, especially in the morning. Nutrient uptake through the leaves is also greater in the day than at night, making morning applications more desirable than evening sprays.