Watering the lawn is an important part of maintaining a healthy, green yard during the summer months. However, when temperatures climb to extreme highs, it’s important to understand how the heat can impact your grass and when it’s best to hold off on watering. Knowing what temperature is too hot to water grass can help you avoid causing further stress or damage to your lawn on extremely hot days.
What Happens to Grass When it Gets Too Hot?
Grass thrives best when temperatures are between 60-75°F. Once temperatures climb above 90°F for extended periods of time, the grass plant can start to experience heat stress. Some of the signs your lawn is getting too hot include:
- Wilting, drooping, or curling leaf blades
- Grass turning blue-gray or brown
- Thatch buildup
- Increased susceptibility to pests and diseases
The hotter it gets, the more likely the grass blades and roots will be damaged. If the temperatures are extreme enough, the grass can enter dormancy to protect itself. While grass can recover from short-term heat stress, extended periods of excess heat can seriously damage or kill the lawn.
How Does Watering Impact Grass in Hot Temperatures?
Understanding exactly how temperature impacts watering the grass is key to knowing what’s too hot for irrigation. Here are several factors to consider:
Evaporation Increases
As temperatures rise, the rate of evaporation also increases. When you water grass on a hot day, the water can evaporate before it even has a chance to soak into the soil. This leaves the lawn and soil parched.
Heat Magnifies Dryness
Many people water their lawns daily when its hot without checking soil moisture. While the top grass blades may appear dry on a 90°F+ day, the soil underneath may still be moist. Watering when its already hot only magnifies dryness in the grass and wastes water.
Roots Can’t Absorb Water
When grass plants experience heat stress, the roots become less efficient at absorbing water and nutrients from the soil. Pouring more water on the lawn can’t counteract this issue. The grass roots simply can’t utilize extra irrigation when already wilting from heat.
Increased Evaporation of Dew
Normally, dew formed overnight can provide moisture to help grass plants withstand daytime heat. But when its excessively hot, that dew rapidly evaporates in the morning before the grass has a chance to absorb that moisture.
Poor Moisture Utilization
Warm season grasses thrive better in high heat than cool season varieties, but even the heat tolerant grasses don’t properly utilize moisture when temperatures rise above 90°F. The plants lack the ability to take advantage of irrigation during extreme heat.
What Temperature is Too Hot to Water My Grass?
Experts generally agree that once ambient air temperatures reach 85-90°F, it’s best to avoid or reduce watering the lawn. The hotter it gets past that point, the less effect irrigation will have beyond wasting water.
If you’re wondering specifically what temperature is too hot to water the grass, a good rule of thumb is:
- Avoid watering if temperatures will remain above 90°F all day
- Stop watering altogether once it reaches 100°F or higher
The peak temperature for the day is most important to consider versus the morning or evening temps. Pay close attention to the forecasted high temps and adjust your watering schedule accordingly.
Tips for Watering Grass in Hot Weather
When temps start soaring, you’ll need to adapt your lawn irrigation strategy. Here are some best practices for watering grass during hot temperatures:
Water Early in the Morning
Watering grass before 10 am gives the lawn a chance to absorb the moisture before the midday heat causes rapid evaporation. Early morning watering can reduce water loss by 25% compared to mid-day. Just be sure to check that dew hasn’t already moistened the lawn.
Increase Duration, Not Frequency
Water deeply but infrequently when it’s hot rather than frequent light sprinklings. Short 5-10 minute waterings will simply evaporate. But a deep 60+ minute soak every few days is better utilized.
Cycle Soakings
Split your watering time into 3-5 intervals with breaks in between cycles. This allows the moisture time to properly soak into the soil instead of pooling and running off on the surface.
Mow Less Frequently
Let the grass grow a bit taller, at least 3-4 inches. The longer blades provide shade to protect the soil. But don’t remove more than 1/3 of the height when mowing, which adds heat stress.
Use Sprinkler Heads Efficiently
Oscillating and pulsating sprinkler heads evenly distribute water and avoid excessive runoff compared to stationary sprinklers. Position sprinklers to avoid pavement and playa areas.
Monitor for Wilting
Visually check for wilting grass midday. Water just until the leaves perk up then stop, even if your total duration hasn’t elapsed. Avoid overwatering when its hot.
Water Early or Late in the Day
Its best to avoid watering from about 10 am to 6 pm when peak heat can cause evaporation. Cooler dusk or dawn temps allow better moisture absorption.
Adjust Watering Based on Grass Type
Warm season grasses like bermuda and zoysia need 35-45% less water than cool season grasses. Reduce irrigation accordingly if you have a heat tolerant grass variety.
Let Grass Go Dormant
If allowing the lawn to go dormant through the hottest summer months is an option where you live, skip watering altogether when its above 90°F.
Alternative Lawn Care When Its Too Hot
When you need to decrease irrigation due to heat, incorporate other maintenance practices to keep your grass healthy through times of stress:
- Mow higher: Raise mowing height by about 30% to provide shade to grass crowns.
- Use a sun screen: Apply light monthly doses of Ferrous Sulfate to act as a liqud sunscreen.
- Try anti-stress treatments: Foliar sprays like yucca extracts help reduce heat damage.
- Boost nutrients: Fertilize lightly to aid growth of new, healthy blades.
- Overseed bare spots: Filling patches helps covered soil retain moisture better.
- Control pests: Treat for chinch bugs, armyworms, and other pests that thrive in hot weather.
Letting the lawn go dormant until temperatures cool back down is another low-maintenance option. Just be sure to water occasionally, about every 3 weeks, even dormant lawns.
Watching the Forecast is Key
Paying close attention to weather forecasts will be critical to adjust watering for heat. When high temps are predicted to exceed 90°F for multiple days in a row, it’s best to hold off on irrigation.
Shorter spikes of hot weather likely only need reduced watering. But extended excessive heat means its time to stop watering altogether until the temperatures start dropping back to normal summertime highs.
Making note of the daytime high temps in your area each year can help you determine what temperatures your lawn can tolerate before heat stress occurs. Some key benchmarks include:
- 85°F: Reduce watering duration by 25%
- 90°F: Water only when grass shows wilt signs
- 95°F: Stop all watering until the heat decreases
- 100°F or above: No irrigation at all
As long as you have about an inch of rainfall per week either from irrigation or natural precipitation, the grass should remain healthy through short stints of hot weather. But excessive heat and dryness for weeks on end will take its toll, no matter how much you water.
Signs its Too Hot for Watering Grass
In addition to the actual temperature, visually inspecting the lawn for signs of heat stress can confirm its time to modify your watering habits, including:
- Wilting or folded blades: Indicates the grass desperately needs water.
- Blue-gray coloring: Signals the beginning stages of heat damage.
- Water beading up: Demonstrates the grass can’t properly absorb the moisture.
- Footprints lingering: Reveals the lawn is too dry to bounce back when compressed.
- Drought dormancy: Confirms the grass has shut down to conserve energy.
Let the visual cues from the grass determine if its the right time of day or night to irrigate during hot spells. Learn when to skip watering altogether based on the forecast and lawn health cues rather than sticking to a regimented schedule.
Using Caution When Watering Returns
After an extended hot and dry period, it will take some time for the grass to fully recover. When the weather improves, ease back into watering gradually to avoid shocking the lawn.
Some tips for restarting lawn irrigation after excessive heat include:
- Hand water or use sprinklers on the lowest setting at first
- Start with just 15-20 minutes daily then gradually increase duration
- Wait until temps have dropped back near 85°F to water
- Water in early morning or late evening
- Include breaks to allow moisture to soak in
Rushing back into frequent daily watering can damage heat-stressed grass. Ease back into your normal irrigation schedule over 7-10 days. And stay vigilant of hot temperatures the remainder of the summer to adjust watering appropriately.
Overseeding to Repair Heat Damage
If parts of your lawn didn’t survive the hot, dry weather, you can repair those patches by overseeding once temperatures cool. Here are some tips for repairing heat-damaged grass areas via overseeding:
Wait Until Fall
The ideal time to overseed is September when daytime temps fall below 80°F. This allows tender new grass to establish before cold weather arrives.
Mow, Dethatch, and Aerate
Prep the lawn by mowing short, dethatching, and aerating for good seed-to-soil contact.
Select a Heat-Tolerant Grass
Choose a variety like Bermuda or Zoysia that can better withstand your area’s summer heat. Match species to existing grass.
Use Starter Fertilier
Spread starter fertilizer high in phosphorus to aid new seedling development.
Water Frequently
Keep the top 1/4 inch of soil moist so the seeds germinate and young grass roots establish.
Be Patient
It will take a full year before new grass is mature enough to survive hot summers on its own.
Proper fall overseeding and care provides resilient grass that is better prepared for your area’s typial summer heat. Overseeing also thickens up the lawn to help retain moisture.
Installing Underground Irrigation for Hot Climates
While convenient, above-ground sprinklers and hoses may not be the most efficient methods of watering grass during scorching summers. Installing an underground irrigation system tailored to your lawn allows greater control and less evaporation when its hot out.
Hire an Irrigation Professional
Having a professionally designed irrigation system ensures optimal placement and spacing of heads for even coverage.
Choose Drip Irrigation Around Landscaping
Drip irrigation or micro-spray heads prevents water loss from wind and evaporation in planted beds.
Include Smart Technology
Connect the system to Wi-Fi so you can control schedules from your phone and integrate weather sensors to skip cycles if its rained.
Include Multiple Zones
Group sprinkler heads into zones based on sun exposure, soil type, and plant water needs.
Water Early Mornings
Program the system to water between 2-8 am to minimize evaporation but avoid soaking the lawn just before sunrise.
Account for Pressure
Static pressure over 50 PSI can mist and drift, while under 30 PSI provides insufficient sprinkler coverage.
Examine Spray Patterns
Inspect heads to make sure water evenly reaches the entire lawn without any dry patches.
Upgrading to a water-efficient underground irrigation system provides optimal lawn hydration even during the heat of summer.
Tips to Reduce Grass Water Needs When Hot
In addition to smart watering practices, you can use other methods to lower the lawn’s water requirements during times of excessive heat:
- Allow grass to grow taller to provide shade to soil
- Leave clippings on the lawn to insulate and add moisture
- Use a mulching mower to cut grass into smaller pieces
- Minimize fertilizer which promotes excessive growth needing more water
- Improve soil quality to retain more water naturally
- Reduce lawn area and install drought-resistant plants and mulch beds
Optimizing grass height, minimizing runoff, using shade, and promoting deep root growth are organic ways to maintain a healthier lawn that requires less water.
Grass Alternatives for Hot, Dry Regions
If you live in a climate that’s regularly hot and dry during the summer months, traditional grass lawns may be difficult to sustain long-term even with proper watering techniques. Consider these alternatives to reduce maintenance and water usage while still enjoying green outdoor spaces:
Artificial Turf
Artificial lawns require no irrigation, mowing, or other care. Modern turf looks quite realistic but be sure its pervious to reduce runoff.
Native Groundcovers
Plants native to hot, arid regions like sedum, aloe vera, and creeping thyme stay green with minimal water usage.
Rock Gardens
Decorative gravel, stone, pebbles, and boulders can be quite attractive and low-maintenance while conserving water.
Paver Patios
Installing patios, walkways, or driveways using pavers instead of pavement limits heat reflection while preventing the need to water those areas.
Drought-Tolerant Shrubs
Bushes and shrubs suited for desert climates, like oleander, Texas sage, and dwarf yaupon holly, conserve moisture once established.
Dry Creek Beds
Filled with colorful stones, dry creek beds divert rainwater runoff while enhancing landscapes with their meandering visual interest.
With creative designing using plants, materials, and hardscapes suited for drought conditions, you can still achieve a vibrant outdoor living space while conserving precious water during hot spells.
Conclusion
Determining what temperature is too hot to water grass requires paying close attention to weather forecasts, grass health cues, and moisture levels in your particular environment. While there are general guidelines, each lawn has its own tipping point.
Aim to water only when necessary, delivering deep soakings early or late in the day to minimize evaporation loss. Letting the lawn go dormant in peak summer allows it to conserve energy safely until temperatures become hospitable again in fall.
Adjusting watering techniques, improving soil, modifying grass height, and using alternatives can all help sustain your lawn through times of excessive heat without wasting water. With some vigilance and adaptations, you can maintain a healthy grass lawn despite hot, dry periods during the summer.
