A Complete Vegetable Watering Guide

Apr 30, 2021 09:00AM ● By Thrive and Grow Gardens

How much water do plants really need? When is the best time to water our vegetables? How do we check soil moisture? Learn to make the right call when it comes to that essential task of watering.

1. Find the root zone for each plant.

Before we try to determine how much water our plant needs, we need to know where its roots are; this is referred to as the root zone. We can visualize this by imagining the plant’s leaves and stems upside down in the ground.

Use the above illustration to help visualize the plant’s root zone in correlation with its leafy growth. Direct-seeded plants need more frequent, shallow watering versus a full-grown plant. Some plants like lettuce have very shallow root zones (one foot deep by 1 foot in diameter), where other plants like tomatoes and corn can have a rooting depth of up to eight feet deep.

2. Check soil moisture.
Dig down to the outer edges of the root zone, grab a handful of soil and perform the “Squeeze Test”. Squeeze the handful of soil as hard as possible; if drops come out, it’s too wet. Release grip; if the soil doesn’t hold a ball, it’s too dry. A shiny ball with no drops of water shows proper soil moisture.

Don’t check moisture immediately after watering. To get an accurate reading, wait at least five to 10 minutes after watering. Check the soil moisture every day on newly planted seedlings/seeds. Check two or three times per week for established vegetables.

Once we know what to look for, simply sticking a finger in the ground on the root edges and feeling where the moisture starts can replace the squeeze test.

3. Apply water.
It’s always best to water early in the morning; this will help keep leaves dry, discouraging disease. Watering during a cooler time will also cause less evaporation, giving the soil optimum time to soak up every drop of water we give it.

When hand-watering, use a fine nozzle. Try to imitate rain, nothing high-pressure. Despite common myths, we can hand-water plants if they show drought stress during a hot day; just check to make sure the soil actually needs it. One recommendation is the DRAMM nozzle, which can be attached directly to a hose, or try a DRAMM wand.

Drip irrigation or ollas are the most efficient option, providing a slow-and-steady application. After applying water, wait five to 10 minutes and check the soil moisture again. It can take up to three waterings to adequately wet dry soil. For very hydrophobic potting soils or compost, a surfactant like YuccaWet is a good option.

If we only water where the roots currently are, the plant will never want to venture deeper in the soil. We want to train the roots to drill down and out, so remember to check the soil moisture around the outer edges of the root zone.

For a pre-emerged seed, keep all the soil near the seed adequately moist. As the plant matures and has a larger root network, we can focus on deep and infrequent watering to lower our water bill and have deep-rooted, drought resistant plants.

Proper watering is one of the most underestimated practices for having healthy plants. Lots of issues can arise from improper soil moisture. Using these tips and tools can help a garden thrive, no matter what Mother Nature throws our way.

Thrive and Grow Gardens is a local vegetable gardening educator and raised bed design and build company, located in Tucson.Connect at 520-305-3127 or ThriveAndGrowGardens.com. See ad, page 12.

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