Guides

Longer answers to the questions growers type into a search box — each one ends in a calculator that works the case for you.

• The growing degree days formula, step by step

  One day's growing degree days are its average temperature above a base. The corn method caps the high and floors the low first — which is where most hand calculations go wrong.

• How much fertilizer per acre do you need?

  A rate of nitrogen is not a rate of fertilizer. Divide the nutrient you want by the share of it in the product, and check the rate against advice rather than habit.