Crop farming · Planting
Seed spacing for a target population.
Row width, final plants per acre and emergence become seeds per acre and inches between seeds. Check a planter setting or a stand count too.
Inputs
Spacing and population
Enter the values.
How to space seeds for a target plant population
An acre is 43,560 square feet. Seeds per acre = final population ÷ emergence. Seeds per row foot = seeds per acre × row width in feet ÷ 43,560, and the spacing between seeds in inches is 12 ÷ seeds per row foot. The seeds-per-row-foot formula is in University of Georgia Extension Circular 813; the spacing is 12 divided by it.
Worked example. 22,000 final plants per acre, 30-inch rows, 85 percent emergence. Seeds per acre = 22,000 ÷ 0.85 = 25,882. Seeds per row foot = 25,882 × 2.5 ÷ 43,560 = 1.485. Spacing = 12 ÷ 1.485 = 8.1 inches. The UGA corn table lists 8.1 inches and 25,900 seeds per acre for the same row. For the default inputs here (32,000 plants, 30-inch rows) the answer is 5.6 inches and 37,647 seeds per acre.
Stand counts. UGA's method for checking a stand is to count the plants in a length of row equal to 1/1000 of an acre, average several counts and multiply by 1,000. That length is 43.56 ÷ row width in feet, which is 17.4 ft for 30-inch rows and 74.7 ft for 7-inch rows, matching UGA's table (74 ft 8 in).
Planters seldom drop seeds perfectly evenly, and emergence changes with soil temperature and moisture. Treat the spacing as a planter setting target, not a promise of final stand.
Frequently asked questions
How many inches between corn seeds for 32,000 plants per acre?
In 30-inch rows with 85 percent emergence, 32,000 plants per acre needs 37,647 seeds per acre, which is a spacing of about 5.6 inches.
How do I do a stand count?
Measure a length of row equal to 1/1000 of an acre (17.4 ft in 30-inch rows), count the plants, repeat in several places, average them and multiply by 1,000 to get plants per acre.
What emergence should I use?
The UGA corn planting table assumes 85 percent. Use a lower number for cold, wet or crusted seedbeds, or your own past emergence counts.
Does this work for crops other than corn?
The arithmetic is the same for any row crop: acres, row width, seeds per acre and emergence. Enter that crop's target population and your row width.
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Not professional advice
Target populations vary by hybrid, soil and moisture. Use your seed company or extension recommendation for the target and this tool for the arithmetic.