By Eric Evans, Camden, Maine
In most soils, watering is needed during extended droughts (our 1-2 inches of rain for all of June and July in 2022 was not enough!) to support blooming and fruiting. But frequent shallow watering can have little benefit, because it encourages shallow rooting and evaporates rapidly. I aim to provide the equivalent of at least 1 inch of rain each week in a single watering, like the all-day soaker rains that we know are perfect but happened only once for us here this summer.
It is very easy to underestimate what it takes to provide 1 inch of “rain” from a garden hose. I always aim to provide 1 gallon of water per square foot of garden, because it’s easy to remember that rule of thumb — and a gallon of water on a square foot of area is actually about 1 1/2 inches deep. If I’m using a sprinkler that covers a 20-foot-by-30-foot area, that’s 600 square feet. To get 600 gallons for those 600 square feet from the sprinkler doing 5 gallons per minute, I need to run the sprinkler for 120 minutes (600 square feet divided by 5 gallons). Or put some tin cans out there and sprinkle until the water is 1 inch deep in them all. I usually use 50-foot floppy drip hoses for watering and run them in lines 2 feet apart. So I guess I’m watering 100 square feet with a 50-foot drip hose (50 feet multiplied by 2 feet). One hundred square feet needs 100 gallons. At 5 gallons per minute that will take 20 minutes.
If you are watering a small area with a wand, run the water into a bucket for a minute to estimate the delivery of water in gallons per minute — probably somewhere between 2-5 gallons per minute. Estimate the area you are watering, then divide by the flow rate to get the needed minutes: 10 feet by 10 feet equals 100 square feet; divide by 3 gallons per minute, for 33 minutes without moving away from that 10 by 10 area.
This tip was originally published in the winter 2022-23 issue of The Maine Organic Farmer & Gardener.
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