In the hottest months, expect to water every day or every other day.
As recorded: In a month whose normal days run above 90 F (32 C) and whose normal nights stay above 70 F (21 C), a vegetable garden may need water daily or every other day.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
Heat speeds both the water plants draw from the soil and the water the soil loses to the air, so after each watering the soil is dry again sooner.
What to do about it
In those months check the soil every day, and expect to water daily or every other day, early in the morning, at the soil and down to the roots. The soil still decides: if it is moist at the second knuckle, wait.
How much it matters: UMN keeps the amount at the inch a week and splits it up: 'In a 10x10-foot garden, this would mean giving your plants 8 to 9 gallons of water each day' (its 62 gallons a week over 7 days). The heat changes how often; Arizona's '2 to 4 times a week in the warmest/driest summer months' is the same order. No source read gives a larger weekly amount for the heat, so none is stated.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
During extremely hot weather (daytime temperatures above 90°F and nighttime temperatures above 70°F), try to water daily or every other day. In a 10x10-foot garden, this would mean giving your plants 8 to 9 gallons of water each day.
As a rule, it will be necessary to irrigate your vegetable garden 2 to 4 times a week in the warmest/driest summer months and once or twice per week or less in other seasons.
Where this rule stops
It reads each month's normal highs and lows, so it marks the months that are usually this hot and cannot see a heat wave in a milder month. UMN gives these numbers for 'extremely hot weather'; the monthly normal stands in for the weather itself.
Read next
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Details updated
- A person read the sources and confirmed it
- Added to the rules
Cite this page
Milpa Gardens. "In the hottest months, expect to water every day or every other day." Evidence grade: Promising. https://milpa.garden/rules/month-whose-normal-days-run-above-90/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
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How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.