How much water does a 10×20 vegetable garden need?

Two hundred square feet is a solid family vegetable plot. It is also about the size a couple of rain barrels can meaningfully help with: 125 gallons a week is a little over two full 55 gal barrels, so between rains they will cover part of the watering.

What to know about watering a 10×20 vegetable garden

Subtract the rain first. Put a rain gauge in the plot: if half an inch fell this week, the garden only needs about 62 more gallons, one session instead of two. Most overwatering in vegetable gardens comes from running the full schedule after a wet week.

Put the water on the soil, not the leaves. A sprinkler over 200 sq ft wets the paths and the foliage along with the beds; soaker hoses or drip lines snaked along the rows put nearly all of it at the roots, and under mulch they lose less to evaporation. They are slow, though, so the run time goes from about a quarter of an hour on a hose to an hour or more, which is what a hose timer is for.

Watch the heavy drinkers. Tomatoes, squash and cucumbers carrying fruit in July often need more than the weekly inch, especially in sandy soil, while a bed of established onions or herbs needs less. Water deeply enough to wet the soil several inches down, then let the surface dry between sessions.

Smaller plots scale down fast. A single 4 × 4 ft bed needs only about 10 gallons a week; see how many plants fit in a 4×4 square foot garden. For how much a roof can collect toward this, use the rain barrel calculator.