As indicated by soil analysis, prior to seeding or with starter fertilizer. Too much zinc can be harmful, particularly to cereal crops, so soil analysis testing is necessary, and amounts needed vary by crop.
Zinc is essential for plant enzymatic processes, including photosynthesis and the production of indoleacetic acid, affecting stem length, leaf size, and overall yield. If soil temperatures remain cool during spring planting and early growth, zinc supplementation may be particularly beneficial. Some crops however, may not require additional zinc, and caution is needed to avoid zinc toxicity.