Growing food2 min read

Watering a vegetable garden

How much, how often, and the best way to do it

How much

Vegetables need about 1 inch (2.5 cm) of water a week, from rain and watering combined. Sandy soil, and hot, windy, dry days, call for more.

One inch of water over 100 square feet (9 square meters) is about 62 gallons (235 L). With a garden hose, an inch over a large bed takes longer than you'd think, often an hour or two.

Deep and less often

One thorough watering a week beats frequent light sprinkles. Water until the soil is moist at least 6 inches (15 cm) down, which grows deep roots that ride out dry spells. Dig in with a trowel to check.

Fast-growing salad greens are the exception; they like lighter, more frequent watering. Overwatering wastes water and washes nutrients out of the soil.

The best way

How you water matters as much as how much.

Water in the morning when you can. Leaves that stay wet overnight invite disease.
Use soaker hoses or drip lines. They put water at the roots, use far less of it, and keep leaves dry.
With soaker hoses or drip, evening watering is fine, since the leaves stay dry.
Mulch with straw, leaves or compost to hold moisture in.

When it matters most

Water is most important while seeds sprout, right after transplanting, and when plants flower, set fruit and fill out their fruit, heads or roots.

Dry spells and uneven watering cause blossom end rot in tomatoes, peppers and squash, and swings in moisture can make fruit crack. Drought also makes lettuce and cucumbers bitter.

Measure it

A rain gauge tells you how much nature supplied. Hand watering is the least efficient way to water a big garden. To time a sprinkler, set a few straight-sided containers, like tuna cans, in its path and see how long it takes to collect an inch.

Pots and raised beds dry out much faster than garden soil, so check them daily in summer.

Sources

General guidance, not a diagnosis. Written by PlantWiz in our own words from the sources above.