Fruit & Perennials
Grape (Table/Wine) Irrigation Guide
Grape (Table/Wine) runs a 240-day season with water demand peaking at a crop coefficient of 0.85. On a hot mid-summer day (ETo of 6 mm), that is about 5.1 mm per day, or 36 mm (1.4 inches) per week. Every number on this page comes from the FAO-56 standard and is exactly what RainRule schedules with.
Season length
240 days
20 + 40 + 120 + 60 by stage
Root depth
1.5 m
≈ 4.9 ft at maturity
Peak daily use
5.1 mm
at mid-season, ETo 6 mm/day
Depletion threshold
45%
of available water before stress
Crop coefficient (Kc) through the season
Multiply any day's reference evapotranspiration (ETo) by the Kc below to get Grape (Table/Wine)'s actual water use that day.
| Stage | Length | Kc | What's happening |
|---|---|---|---|
| Initial | 20 days | 0.3 | Establishment: bare soil dominates, low water use |
| Development | 40 days | 0.3 → 0.85 | Canopy closes; demand ramps day by day |
| Mid-season | 120 days | 0.85 | Full canopy: peak water use, most stress-sensitive |
| Late season | 60 days | 0.85 → 0.45 | Maturation: demand tapers toward harvest |
Refill points by soil type
Total available water (TAW) is what your soil holds across Grape (Table/Wine)'s 1.5 m root zone. Irrigate when the running deficit crosses the refill point (RAW), 45% of TAW for Grape (Table/Wine), so the crop never enters stress.
| Soil | Holds (TAW) | Irrigate at (RAW) | Days of peak use per refill |
|---|---|---|---|
| Sand | 105 mm | 47.2 mm | ~9 days |
| Sandy Loam | 180 mm | 81 mm | ~15 days |
| Loam | 225 mm | 101.3 mm | ~19 days |
| Silt Loam | 255 mm | 114.8 mm | ~22 days |
| Clay Loam | 240 mm | 108 mm | ~21 days |
| Clay | 210 mm | 94.5 mm | ~18 days |
Sandy soils hold the least water, so Grape (Table/Wine) on sand needs small, frequent irrigations; clay holds the most and supports longer intervals with bigger applications.
Worked example: a peak-summer week
Take Grape (Table/Wine) at mid-season on a week averaging an ETo of 6 mm/day:
- Daily crop use: 6 mm × Kc 0.85 = 5.1 mm/day
- Weekly demand: 5.1 × 7 = 35.7 mm (1.4 inches)
- On loam (101.3 mm refill point), a full profile lasts about 19 days with no rain before irrigation is due.
Real weeks aren't averages: ETo swings with heat waves and rain changes everything. That's the gap between a rule of thumb and a live schedule.
Related fruit & perennials guides
Get a live schedule for your grape (table/wine) field
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