Foliar zinc spray usually works faster because zinc is applied directly to the leaves. Soil application can support long-term nutrition, but it may work slowly, especially in high-pH or alkaline soils where zinc becomes less available to roots.

Zinc may be present in the soil, but plants may not absorb it properly due to high soil pH, cold or wet soil, low organic matter, excess phosphorus, waterlogging, compacted soil, or weak root growth.