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Crop Calendar Tools

Simple calculators with the formula shown above each one. They run in your browser and send nothing anywhere.

Growing degree day calculator

GDD per day = ((daily high, capped at your cap + daily low, raised to your base) / 2) - base. Sum the days. Negative results count as 0.

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Base and cap vary by crop and source; use the values your extension service publishes for your crop. Background: NOAA NCEI, eXtension.

Row feet per acre = 43,560 sq ft x 12 / row spacing in inches = 522,720 / spacing. Seeds per foot = seeds per acre / row feet per acre.

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Arithmetic only. Use the seeding rate your seed company and extension service recommend.

Seeds to plant = target plants / (germination x field emergence). Germination and emergence are entered as percentages and divided by 100.

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Field emergence is your own estimate from past stands.

lb per acre / 43.56 = lb per 1,000 sq ft. 1 kg per hectare = 0.892179 lb per acre.

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An acre is 43,560 square feet; the kg/ha factor is the standard metric conversion.

Pounds of nutrient = bag weight x nutrient percent / 100. Cost per pound of nutrient = bag price / pounds of nutrient.

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Use your soil test and extension recommendation to decide how much nutrient to apply.

Maturity date = planting date + days to maturity (from the seed packet or variety sheet).

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Cool weather lengthens the real time to maturity. Growing degree days are a better guide for some crops.

Target date = your last spring frost date + (weeks x 7). Use a negative number for weeks before the frost date.

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Find your own frost dates from NOAA or your extension office. Each crop guide explains which offset to use.