How to water your lawn properly: 5 rules that change everything

Most people water their lawn too often and not deeply enough. Five minutes of light sprinkling every day trains the roots to stay near the surface, where they dry out fast. One long deep soak twice a week pushes the roots down, where the soil stays cool and moist. Same total water, completely different lawn.

Here are the five rules that turn a thirsty lawn into a tough one.

Rule 1 — Deep and not very often

This is the big one. Water hard, then leave the lawn alone for several days.

Why? Roots chase water. If you water a tiny bit every day, the roots stay in the top 2cm of soil because that's where the water is. Then a heatwave hits, the top dries out in a day, and the lawn collapses.

If you water deeply once or twice a week, the water soaks down to 15-20cm. The roots follow it. Now your lawn can handle a week of heat without breaking a sweat because the deeper soil stays moist for ages.

The goal: soak the soil to about 15cm deep, then walk away until it starts to dry out.

Rule 2 — Water in the early morning

Between 4am and 9am is the best window. Here's why:

• Less evaporation. The sun is low and the air is cool. Most of the water gets to the roots.
• Less wind. Calm mornings mean even coverage from a sprinkler.
• Leaves dry off before night. Wet grass overnight is fungus's favourite thing. Morning watering gives the blades all day to dry.

The worst time is evening. The grass stays wet for 12 hours and disease moves in fast.

If you can only water at one time of day, make it early morning. Set a sprinkler timer if you're not up that early.

Rule 3 — The screwdriver test

You don't need a moisture meter. A long screwdriver works just as well.

After watering, push a long screwdriver into the soil. If it slides in easily up to the handle, the soil is moist all the way down. You've watered enough. If it stops short, you haven't. Water more.

Before your next watering, do the same test. If the screwdriver still goes in easily, skip the watering — the soil is still wet underneath. If it's hard to push in, time to water again.

This single test will stop you overwatering more than anything else.

Rule 4 — The tuna can test

You probably have no idea how much water your sprinkler puts out. Most sprinklers vary a lot, even across the same patch of lawn.

Here's how to find out:

1. Put 3-5 empty tuna cans (or similar shallow containers) across the lawn at different distances from the sprinkler.
2. Turn the sprinkler on for 30 minutes.
3. Measure the water depth in each can with a ruler.

You want about 2-3cm of water in the cans to soak the soil deeply. If you've only got 1cm after 30 minutes, you need to run the sprinkler twice as long. If the cans vary wildly, your sprinkler coverage is uneven and you need to move it around or upgrade it.

Do this once. You'll know forever how long your sprinkler needs to run.

Rule 5 — Read the signs

The grass tells you when it needs water. You just have to look.

Signs of underwatering:

• Footprints stay visible after you walk on it (grass loses springiness)
• Blue-grey or dull colour instead of bright green
• Leaves fold in half lengthwise
• Soil is rock-hard

Signs of overwatering:

• Spongy or soggy underfoot
• Mushrooms popping up
• Yellow patches that stay wet
• Moss creeping in
• Mosquitoes hanging around

If you see signs of overwatering, stop watering for a week or two. Most lawn problems come from too much water, not too little.

How often should I water?

Depends on the season, the grass, and the weather. Here's a rough guide for a healthy lawn with decent soil:

Skip a watering after heavy rain. Add a watering during a heatwave. Use the screwdriver test to make the call.

What sprinkler should I use?

For most home lawns, you have three options:

• Oscillating sprinkler. The classic fan-shaped one. Good for rectangular lawns. Lots of evaporation loss because the water flies high.
• Rotary or impact sprinkler. Throws water in a circle. Better coverage and less evaporation. Best for medium to large lawns.
• In-ground irrigation. Set and forget with a timer. Best long-term option but costs to install.

Whatever you've got, the rules above still apply. Run it long enough to soak deep, then leave the lawn alone for a few days.

Common watering mistakes

• Daily sprinkling. The number-one cause of weak, shallow-rooted lawns.
• Watering at midday. Half the water evaporates before it hits the soil.
• Watering when it's about to rain. Check the forecast. Free water is free.
• Same time every week even after rain. Sprinklers on timers need to be paused after big storms.

Frequently asked questions

How long should I water for?

Long enough that a screwdriver pushes easily into the soil afterwards. For most sprinklers and most lawns, that's 30-45 minutes per zone.

Can I water in the evening if I can't do mornings?

Late afternoon is okay (4-6pm gives the leaves time to dry before dark). Avoid watering after sunset.

Should I water new grass differently?

Yes. New seed or new sod needs light watering daily for the first 2-3 weeks. Once the roots are down, switch to deep and infrequent.

What about during a water restriction?

Water deeply on your allowed days. A wetting agent (a soap-like product that helps water soak in) makes the most of each session. Avoid watering daily even when allowed.

Is greywater okay?

Yes, as long as it's free of bleach, strong detergents, or salty soaps. Most plant-safe washing-up water is fine on the lawn.

How Lawnova helps

Lawnova checks your local rainfall, temperature, and grass type to tell you exactly when your lawn needs water. No daily guessing. No wasted water. Just a quick reminder when it's actually time to soak it. Sign up here.