🌽 Corn Plant Water Calculator
Calculate precise irrigation needs for your corn crop by growth stage, plot size, and soil type
| Growth Stage | Days from Plant | Water / Week (in) | Water / Week (mm) | Total Need (in) | Critical? |
|---|---|---|---|---|---|
| Germination (VE–V2) | 0–10 | 1.0 – 1.25 | 25 – 32 | 1–2 | Yes — needs moisture |
| Vegetative (V3–V12) | 10–60 | 1.0 – 1.5 | 25 – 38 | 8–12 | Moderate |
| Tasseling (VT) | 60–70 | 1.5 – 2.0 | 38 – 51 | 3–4 | ⚠️ Critical |
| Silking (R1) | 70–77 | 1.5 – 2.0 | 38 – 51 | 2–3 | ⚠️ Most Critical |
| Blister (R2) | 77–87 | 1.25 – 1.75 | 32 – 44 | 2–3 | High |
| Dough / Dent (R4–R5) | 87–110 | 1.0 – 1.5 | 25 – 38 | 4–6 | Moderate |
| Grain Fill (R3–R5) | 87–115 | 1.0 – 1.25 | 25 – 32 | 5–8 | Moderate |
| Maturity (R6) | 115–130 | 0.5 – 0.75 | 13 – 19 | 1–2 | Low |
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Mature corn
| Method | Efficiency | Water Applied for 1 in Needed | Gal / 1,000 sq ft / in | Liters / 100 m² / in |
|---|---|---|---|---|
| Drip Irrigation | 90% | 1.11 inches | 692 | 2,590 |
| Sprinkler | 75% | 1.33 inches | 831 | 3,107 |
| Center Pivot | 80% | 1.25 inches | 780 | 2,917 |
| Hand Watering | 85% | 1.18 inches | 735 | 2,749 |
| Furrow / Flood | 60% | 1.67 inches | 1,040 | 3,890 |
| Area | 1 inch of Water (gal) | 1 inch of Water (liters) | Per Plant (gal/wk avg) |
|---|---|---|---|
| 100 sq ft (10×10) | 62 | 235 | 0.6 – 1.0 |
| 200 sq ft (10×20) | 124 | 470 | 0.6 – 1.0 |
| 500 sq ft | 311 | 1,177 | 0.6 – 1.0 |
| 1,000 sq ft | 623 | 2,358 | 0.6 – 1.0 |
| 1 acre (43,560 sq ft) | 27,154 | 102,790 | 0.6 – 1.0 |
| 1 hectare (10,000 m²) | 65,427 | 247,741 | 0.6 – 1.0 |
| Plot Size | Area (sq ft) | Gallons/Week | Liters/Week | Plants (est.) |
|---|---|---|---|---|
| Small 10×10 ft | 100 | 93 | 352 | ~8 |
| Garden 20×10 ft | 200 | 187 | 706 | ~16 |
| Backyard 30×20 ft | 600 | 560 | 2,120 | ~48 |
| Plot 50×30 ft | 1,500 | 1,401 | 5,302 | ~120 |
| Large 100×50 ft | 5,000 | 4,669 | 17,675 | ~400 |
| Strip 200×100 ft | 20,000 | 18,676 | 70,700 | ~1,600 |
Note: The info in this article comes from real-world farming knowledge and from farming discussions.
corn is a crop that requires a lot of water to grow well. As a member of the grass family, it is quite a thirsty plant and commonly requires around one inch of water weekly. Even so during the peak growing stages that amount grows a lot.
How Much Water Does Corn Need
Many watering schedules count corn at about 115 to 120 percent of the water use rate of benchmark grass. In practice that means water needs of up to two inches weekly during the peak use stages.
During the growing season, the seasonal water use of corn can swing between 21 and 28 inches, depending on the local water use rates. The higher the harvest, the more water is needed. A corn crop of 150 bushels per acre uses about 16 inches of water.
At 200 bushels the crop uses around 20 inches. And for 250 bushles, it requires roughly 22 inches of water during the season.
The water use of the crop is affected by weather, the growth stage, the planting date and the planting density. Water use is the water that leaves the soil through evaporation at the ground surface and through the plant. Those two parts together make up the total water use of the crop.
If corn does not receive enough water to cover the water demands during the growing stages, big drops in yield can happen.
water tension during the dough to late stages can rush the maturity. Because of that the kernels do not reach there full potential. For good grain growth and top yield, corn requires water right until full maturity.
Also the soil type matters. Heavy black soils keep water very well, sometimes even too well. The size of the field also matters, when one counts how much water is needed.
One inch of watering means one inch of depth across the whole field. To find the volume, one must know the area of the field.
At bigger scale, corn plants on one acre of ground need to use around 600,000 gallons of water from watering and rain to produce 200 bushels. That results in about 2,400 gallons per bushel in the main corn zone. Most corn acres in United States actually are not watered, and they depend only on rain.
The goal of watering management is to give the extra water that the plant requires, while one also gets the best value from that water. Well timed waterings provide enough water to escape corn tension, and they fully use the rain and the moisture already in the soil. The needs also can range by type and region, so the decision is based on the available watering supply, the water holding ability of the soil, the rate ofwater use and the actual water needs of corn.
