Seed Spacing Calculator
Calculate the optimal in-row seed spacing for your crop based on target population, row spacing, and germination rate. Also computes seeds per foot, seeding rate in lbs per acre, and cost per acre.
Result
Cost Breakdown
Seeds needed: 33,684 seeds per acre
Seed weight: 21.05 lbs per acre (at 1,600 seeds/lb)
Cost per acre: $6736.84 (at $320.00/lb)
How Seed Spacing Affects Your Crop
Proper seed spacing is essential for achieving uniform emergence, reducing competition among plants, and maximizing yield potential. In-row spacing determines how much space each plant has to access water, nutrients, and sunlight. Uneven or incorrect spacing leads to yield loss, variable ear/head size, and harvest inefficiency.
Key formula: In-row spacing (inches) = 43,560 / (Target population / Row spacing in feet / 12). For example, targeting 32,000 plants/acre at 30-inch rows yields approximately 5.45 inches in-row spacing.
Frequently Asked Questions
- What is the ideal in-row seed spacing for corn?
- For corn at 30-inch rows targeting 32,000 plants/acre, the ideal in-row spacing is approximately 5.5 inches. At higher populations (36,000 plants/acre), spacing decreases to about 4.9 inches. Modern planters use hydraulic or electric drives to precisely control seed singulation and spacing regardless of ground speed.
- How does planter speed affect seed spacing?
- As planter speed increases, seed spacing accuracy can decrease due to seed bounce, skips, and doubles. Most planters are calibrated for optimal accuracy at 4-6 mph. At higher speeds (7-8 mph), spacing variability increases significantly. Modern precision planters with hydraulic downforce and electric meters maintain accuracy at higher speeds better than mechanical systems.
- How many seeds per foot should I target?
- Seeds per foot depends on row spacing and target population. For corn at 30-inch rows: 2.2 seeds/foot for 28,000 plants/acre, 2.5 for 32,000, and 2.8 for 36,000. For soybeans at 15-inch rows: 4-6 seeds/foot for 120,000-160,000 plants/acre. For wheat drilled at 7.5-inch rows: 20-30 seeds/foot for 1.5-2.0 million plants/acre.
- What is the difference between seeds per acre and plants per acre?
- Seeds per acre is the number of seeds planted, while plants per acre is the number that actually emerge and survive. The difference is due to germination rate and seedling mortality. For example, corn with 95% germination planted at 33,684 seeds/acre will achieve approximately 32,000 plants/acre. A margin of 5-15% is typically factored in to account for germination losses.
- How do I calculate seeding rate in pounds per acre?
- Seeding rate in lbs/acre = (Seeds per acre) / (Seeds per pound). For example, wheat at 1,500,000 seeds/acre with 12,000 seeds/lb = 125 lbs/acre. Corn at 33,000 seeds/acre with 1,600 seeds/lb = 20.6 lbs/acre. Soybeans at 140,000 seeds/acre with 2,400 seeds/lb = 58.3 lbs/acre.