How much water does a vegetable garden need?
In July and August a vegetable garden needs about 3–5 liters per m² a day. A 100 m² garden therefore needs 300–500 liters a day at the peak of summer. Drip irrigation and mulch save 30–50 %, so the same garden can get by on about 150–350 liters.
Summer water by garden size
| Garden | Liters a day | With drip and mulch | For 30 dry days |
|---|---|---|---|
| 25 m² | 75–125 L | 38–88 L | 2,250–3,750 L |
| 50 m² | 150–250 L | 75–175 L | 4,500–7,500 L |
| 100 m² | 300–500 L | 150–350 L | 9,000–15,000 L |
| 200 m² | 600–1,000 L | 300–700 L | 18,000–30,000 L |
The last column is without drip and mulch. Real needs depend on your climate, soil and crops, so measure and adjust.
Plan for August, not for the year
A place can have twice the water it needs over a year and still run short in August. Springs and wells are at their lowest when the garden wants the most. That makes the driest month the one to plan for.
When water runs short
The order is always the same: people, animals, seedlings and the polytunnel, the garden, and fruit trees last. Drinking and cooking need only about 3–5 liters per person a day, so a shortage in the garden does not have to become a shortage in the house.
Work out your garden's water with the free calculator.
Water budget: what you have and what you need
Measure your spring, well and roof, work out what the house, garden and animals need, and know in advance which month you will run short
- Daily summer demand calculator
- August supply calculator
- Roof rainwater by month
- Monthly water budget
- Spring and well measurement log
- The water year on the homestead
- Drought plan
Sources: FAO, Crop Evapotranspiration (Irrigation and Drainage Paper 56); WHO, Guidelines for Drinking-water Quality; Lancaster, Rainwater Harvesting for Drylands and Beyond.
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