Updated: Dec 15, 2020
How much water do you really need? When is the best time to water your vegetables? How do you check soil moisture? This article can help you make the right call when it comes to that essential task of watering.
1. Finding 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. You 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. You can see why direct-seeded plants need more frequent, shallow watering vs a full-grown plant.
Example: Some plants like lettuce have very shallow root zones (1 ft deep x 1 ft in diameter), where other plants like tomatoes and corn can have a rooting depth of up to 8 ft deep!
2. Checking soil moisture:
Dig down to the outer edges of the root zone, grab a handful of soil, and perform the 'Squeeze Test'.
Squeeze test: squeeze the handful of soil as hard as you can; if drops come out, it’s too wet. Release your 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 5-10 minutes after watering.
Check the soil moisture every day on newly planted seedlings/seeds.
Check 2-3 times per week for established vegetables.
Tip: Once you know what to look for, simply sticking your finger in the ground on the root edges and feeling where the moisture starts can replace the squeeze test.
Tip: For more precise watering, you can purchase a tensiometer: REOTEMP Garden and Compost Moisture Meter (15 Inch Stem), Garden Tool Ideal for Soil, Plant, Farm and Lawn Moisture Testing
3. Applying 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 you give it.
When hand-watering, use a fine nozzle. Try to imitate rain, nothing high-pressure. Despite common myths, you can hand-water your plants if they show drought stress during a hot day; just check to make sure the soil actually needs it! We recommend the DRAMM nozzle. It can be attached directly to a hose, or you can pick up a DRAMM wand. You can get it in a length of either 16" or 30", and the nozzle is interchangeable!
Drip irrigation or ollas are the most efficient option, providing a slow-and-steady application. Our auto-fill ollas and Netafim Dripline are very effective. You can check out our available products here: Olla Irrigation
After applying water, wait 5-10 minutes and check the soil moisture again. It can take up to 3 waterings to adequately wet dry soil.
For very hydrophobic potting soils or compost, a surfactant like YuccaWet is a good option. Yucca Extract- Organic wetting Agent & surfactant
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.
If it's 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 your 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. Use the tools and info listed above to help your garden thrive no matter what Mother Nature throws your way!