How Long Does It Take to Water a Vegetable Garden to a Nine-Inch Depth?

Types of Soil Composition

• Balancing the water for a vegetable garden requires knowing the type of soil you have and the characteristics of how it retains water. Water poured into a soil that has a great amount of sand will quickly flow in a matter of minutes to 9 inches or more, and then evaporate over a short time. A clay-based soil may take several hours for the same amount of water to penetrate to that depth, if it even does, but the water stays in the soil for a longer period. Watering over a heavily crusted soil baked from the summer sun may not even penetrate an inch or two.

Soil Testing

• A quick test will help determine which type of soil you have and the watering strategies you need to employ. Pour a bucket of water over a spot that's central in the garden. Let the water soak into the soil for about 60 minutes. Push away the top inch of soil, and then dig up a handful. Squeeze the soil into a ball in your hand. If the ball wants to retain its shape when you poke it, then it is clay-based. If it immediately crumbles into pieces, then it is sand-based. If the ball retains its shape under moderate poking but crumbles when poked harder, then it is loam, which is the best type of soil.

Adjusting Watering

• According to Larry Bass of North Carolina State University, vegetable gardens need at least 1 inch of water each week, and should be watered to a depth of 6 inches. If the soil is dry at the tip of your index finger when it's poked into the soil, it is time to water. Trial and error will determine how long it takes your specific soil to be watered to the proper depth. After watering, dig a small hole with a trowel to see how far down the water has penetrated, and adjust your subsequent watering techniques based on that knowledge.

Compost Amendments

• Adding compost or composted manure to the soil moderates the effect of either sand or clay, and allows you to manage the water much better. Compost both binds the sand particles together, allowing the water to saturate the soil without flowing away, and breaks the clay particles apart, allowing the water to flow more freely without taking up all the air pockets. Tilling in 2 to 3 inches of compost each fall or spring ensures that the soil is maintained at an optimum state. Compost eventually disappears, so if you skip a few years, the soil soon reverts to its original state.