How Long to Water Your Lawn: Spring Watering Guide 2025
Learn exactly how long to water your lawn this spring—and why it matters for a healthy, green yard.
When it comes to spring lawn care, most homeowners are either watering too much or too little—and wasting money in the process. In fact, up to 50% of outdoor irrigation water is lost to overwatering or system inefficiencies. That’s not just bad for your water bill—it’s bad for your lawn.
Knowing how long to water your lawn isn’t just a guess. It’s a science. And in this guide, we’ll break it all down for you—from calculating exactly how much water your lawn needs, to how long to run your sprinklers, and when to water for the best results.
If you want green, healthy grass that can handle the heat, avoid weeds, and stay thick all season, this article is for you.
Topic | What You Need to Know | Why It Matters |
Watering Goal | 0.65 inches per week in March–April (adjust for rainfall) | Provides enough moisture for healthy root growth without wasting water |
How to Measure Water Output | Use a Catch Can Test: Measure how much water your system puts out in 15 minutes | Helps determine exact run times for your specific sprinklers |
Average Run Times | Spray Heads: 10–11 min, 3x/week Rotors: 20–22 min, 3x/week | Quick estimate if you can’t run a catch test |
Best Time to Water | Early morning (3–6 a.m.) | Reduces evaporation, avoids disease, and prepares lawn for daytime growth |
Overwatering Risks | Fungus, shallow roots, high bills | Too much water weakens your lawn and wastes money |
Coverage Issues | Caused by poor alignment, pressure, or spacing | Leads to dry patches even if you’re watering on schedule |
Adjustment Tips | Use smart controllers (e.g., Hydrawise), watch weather, inspect your system regularly | Keeps your watering plan efficient and responsive |
Seasonal Water Needs | Spring: 3.54″ required – 1.47″ from rain = 2.07″ irrigation need, adjusted to 2.6″ for system efficiency | Helps you avoid under- or over-watering by calculating your true irrigation requirement |
Key Influencing Factors | Sunlight, humidity, temperature, wind, soil moisture | These affect how quickly your lawn loses water |
Final Advice | Water consistently, monitor results, and tweak your system as needed | A thoughtful approach now leads to a stronger, greener lawn all year long |
Why Your Lawn Needs the Right Amount of Water
Think of your lawn like your body on a hot day. If you don’t drink enough water, you get sluggish. But if you gulp too much all at once, you feel bloated and drained. Your grass works the same way.
Too much water? You’ll end up with shallow roots, lawn fungus, and wasted resources. Too little? You get dry, thin patches and stressed turf.
So the goal is simple: give your grass just the right amount of water at the right time.
That’s why knowing how long to water your lawn—especially in spring—is so important. Spring sets the tone for the whole growing season, so proper watering now leads to stronger roots and a healthier lawn later.
How We Calculate Lawn Water Needs
At Vinedresser Lawn & Landscape, we use expert resources like Water Requirements of North Carolina Turfgrasses to determine exactly how much water your grass needs. If you’re not in North Carolina, find a local extension resource to help guide you.
Here’s what affects your lawn’s water needs the most:
- Sunlight: More sun means more water loss.
- Humidity: High humidity slows water loss. Dry air speeds it up.
- Temperature: Hotter weather increases evaporation.
- Wind: Wind pulls moisture from the grass and soil.
- Soil Moisture: Already dry soil can’t hold water well.
The combination of evaporation and plant “sweating” is called evapotranspiration (ET). It’s the main way lawns lose water. To keep your lawn healthy, your watering should replace what’s lost through ET.
We use the Blaney-Criddle method, a proven formula that calculates water needs based on temperature and daylight hours. This gives us a solid starting point to know how long to water your lawn each week.
If your system struggles to keep up, it might be time for a professional irrigation maintenance service to make sure everything is operating efficiently.
How Much Water Does Your Lawn Need in Spring?
Here’s the real math behind spring irrigation:
- Lawns need 3.54 inches of water per month (March–April).
- Rainfall gives us about 2.94 inches, but only 50% is usable—that’s just 1.47 inches.
- Subtract that from the monthly need:
3.54 – 1.47 = 2.07 inches still needed. - Adjust for irrigation system efficiency (most systems are about 80% efficient):
2.07 ÷ 0.80 = 2.6 inches needed by irrigation. - Weekly breakdown:
2.6 ÷ 4 = 0.65 inches per week
So, how long should you water your lawn? Aim for 0.65 inches of water per week in spring, adjusting for any rainfall.
How to Measure Your Sprinkler Output
Every irrigation system is different. That’s why a Catch Can Test is the easiest way to measure how long you need to run your sprinklers.
Here’s how to do it:
- Place several shallow containers (like tuna cans or measuring cups) around one sprinkler zone.
- Run your sprinklers for 15 minutes.
- Measure the water in each container.
- Average the results.
If you collect 0.25 inches in 15 minutes, then you’d need to run that zone for 45–50 minutes total to get 0.65 inches. Split that up over three days a week—about 15–17 minutes per watering.
If your system isn’t performing consistently, it may be time for a sprinkler repair to ensure even distribution.
Average Watering Times by Sprinkler Type
While the Catch Can Test gives you precise data, here are average run times to get you started:
Spray Heads:
- 1 inch of water = 50 minutes
- For 0.65 inches: 32 minutes per week, or 10–11 minutes per session (3x/week)
Rotors & MP Rotators:
- 1 inch of water = 100 minutes
- For 0.65 inches: 65 minutes per week, or about 20–22 minutes per session (3x/week)
Remember, this is just a guideline. You’ll still need to tweak your system based on how your turf responds.
If your system isn’t matching up to these run times, our sprinkler maintenance experts can inspect and fine-tune your setup.
Best Time to Water Your Lawn
Timing matters just as much as amount. The best time to water your lawn is early in the morning, ideally between 3 a.m. and 6 a.m.
Here’s why:
- The water can soak into the soil before it evaporates.
- The grass blades dry quickly after sunrise, lowering the risk of fungus.
- You’ll avoid wasting water during the heat of the day or encouraging disease at night.
Watering in the morning also means your lawn will be dry and mow-ready later in the day.
If you’re still having issues, a smart irrigation upgrade or repair could help automate this timing and boost efficiency.
Watch for Dry Spots and Coverage Issues
Even if you’re watering the right amount, poor coverage can ruin your results. If some areas of your lawn are getting more water than others, you’ll see uneven growth or dry patches.
Common coverage problems include:
- Sprinkler heads not aligned properly
- Mismatched nozzles
- Low water pressure
- Gaps between sprinkler coverage zones
If you’re asking yourself, “Why does my lawn still look patchy?” this could be your answer. Take time to inspect your system and fine-tune your setup.
How to Avoid Overwatering
Overwatering can be just as harmful as underwatering. It leads to:
- Shallow root systems
- Increased weed pressure
- Lawn diseases like fungus and rot
- Higher water bills
To avoid these issues:
- Adjust your schedule when it rains.
- Use a rain sensor or smart controller.
- Stick to the goal: 0.65 inches per week in spring.
Want an easier solution? Install a smart irrigation controller like Hydrawise, which uses Predictive Watering® to automatically adjust based on weather. We can help with system upgrades or irrigation repair if your current controller isn’t cutting it.
Final Tips for Smart Spring Watering
Let’s wrap up with a few expert tips to help you master how long to water your lawn this spring:
- Use a Catch Can Test to fine-tune run times.
- Water early in the morning for best absorption and disease prevention.
- Stick to a schedule of 0.65 inches per week, adjusting for rainfall.
- Monitor your sprinkler coverage and fix issues early.
- Consider smart tech like Hydrawise to automate weather adjustments.
Remember, consistency is key. Just like a good fitness routine or diet, a steady and thoughtful watering plan will reward you with a thick, green, and stress-resistant lawn.
Conclusion: Give Your Lawn What It Needs—No More, No Less
Spring is your chance to set the stage for a lawn that thrives all year. Knowing how long to water your lawn isn’t about guesswork—it’s about giving your turf exactly what it needs to grow deep roots, resist stress, and look its best.
If you want your lawn to look like a golf course without wasting water or time, the key is dialing in your spring irrigation. Whether you measure it yourself or bring in a professional, stick to the target: 0.65 inches per week in March and April.
Need help evaluating your system or adjusting your controller? Schedule sprinkler or irrigation maintenance today and let Vinedresser Lawn & Landscape help you water smarter—not harder.