It is better to avoid strong zinc sprays during full flowering unless recommended by a local agriculture expert or product label. Flowers are delicate, and some sprays may damage blooms depending on dose, weather, and product formulation.

Foliar zinc sprays may show improvement in new growth within 1 to 3 weeks, depending on plant condition and severity of deficiency. Soil-applied zinc may take longer because it must become available in the soil and then be absorbed by roots.