How a row crop planter places seeds

Each row unit on a planter does the same four jobs in a line. Twin discs slice open a narrow furrow at a set depth, a spinning seed meter picks up one seed at a time and drops it down a tube at an even interval, and angled closing wheels press soil back over the seed. Seed spacing in the row and the width between rows together decide how many seeds land on each acre.

Controls

Labels

Animation speed

Row width

Seed spacing in the row

Planting speed

Step through it

Open the furrowTwo discs set at a slight V cut a clean slot. Gauge wheels riding beside them hold the depth steady, often around 1.5 to 2 inches for corn.
Meter one seed at a timeA spinning disc with cells or vacuum holes picks up single seeds from the hopper. Its speed is tied to ground speed so spacing stays even.
Drop down the tubeEach seed falls down a curved tube into the bottom of the furrow.
Close and firmAngled closing wheels squeeze the furrow shut, pressing moist soil against the seed for good germination.
Narrow rowsSwitch to 15 inch rows at the same in-row spacing and the planter puts twice as many seeds on each acre.

From spacing to seeds per acre

An acre is 43,560 square feet, or 6,272,640 square inches. Each seed occupies a rectangle of row width times in-row spacing, so seeds per acre = 6,272,640 / (row width in inches x seed spacing in inches).

Growers usually work backward: pick a target population, then set the meter for the spacing that delivers it. Final plant stand is lower than seeds dropped because not every seed emerges.

Try it: at 30 inch rows, slide the seed spacing from 4 to 10 inches. The rate drops from about 52,000 to about 21,000 seeds per acre. Now raise the speed to 10 mph and watch the meter discs spin twice as fast as at 5 mph to keep that spacing.

Why speed is tricky

At 5 mph with 6.3 inch spacing each row drops about 14 seeds every second. Faster planting means the meter must singulate seeds more quickly and the row unit must stay steady on rough ground, or spacing and depth suffer.

Sources

Seeding Practices for Michigan Crops (E-2107)Michigan State University Extension
Planter Preparation, Maintenance and Calibration (FSA1047)University of Arkansas Cooperative Extension Service

How to cite this model

Avid Solutions International. (2026, November 11). How a row crop planter places seeds [Interactive 3D model]. Avid Field Lab. https://avidsolutionsintl.com/explore/grain-planter

Last updated November 11, 2026

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