When caring for a new lawn, proper watering is essential for the grass to establish a healthy root system. Many people wonder when the best time is to water new grass – in the morning or evening. There are pros and cons to both times, and considerations like weather conditions, grass type, and irrigation system play a role in deciding when to water.
Quick Overview
In most cases, the ideal time to water new grass is early morning, before 10am. Watering in the morning allows the grass blades to dry during the day, which minimizes disease risk. It also reduces water loss from evaporation due to sunlight and wind. The exceptions are during hot, dry, or windy conditions, when evening watering may be better to combat heat stress.
The Benefits of Watering in the Morning
There are several key reasons why early morning is the recommended time for watering new grass:
- Cooler temperatures – Grass prefers to be watered when temperatures are cooler. Watering at dawn when the weather is coolest minimizes evaporation loss.
- Less wind – Wind levels are usually lower in the morning than later in the day, reducing evaporation from the lawn.
- Avoids fungal disease – Watering when the grass is already wet with dew can promote fungal growth. Allowing the grass blades to dry during the day is healthier.
- Prevents scalding – If grass is watered mid-day when sunlight intensity peaks, water droplets can act like mini magnifying glasses and burn the grass.
- Allows deeper water penetration – Watering early gives moisture more time to soak into the soil and reach grass roots before hot sun returns.
- Encourages deeper roots – Frequent light watering leads to short, shallow roots. Morning watering promotes the growth of deep, extensive root systems.
The most important reason to water in the early morning is to give the grass foliage time to completely dry out during the daytime. When grass remains damp for extended periods, it becomes much more susceptible to disease issues like brown patch, dollar spot, or fusarium blight.
What Time is Best for Watering in the Morning?
The optimum window for watering grass is typically between 4-10am. The grass should be dry from overnight dew, and temperatures are still relatively cool. Within this timeframe:
- 4-6am is ideal – Taking advantage of the coolest temperatures right before dawn prevents evaporation loss and avoids interfering with morning dew.
- 6-8am is good – Temperatures are increasing but still considered cool, with minimal winds.
- 8-10am is marginal – Once the sun has risen and winds pick up, watering efficiency decreases.
Ideally, you want to complete the watering cycle for the whole lawn while conditions are still cool and calm in the 6am hour. Adjust your automatic sprinkler settings accordingly.
Why Avoid Afternoon or Evening Watering
While morning is the best time for most situations, it’s also important to understand why afternoon and nighttime watering should be avoided:
- Hot sun causes evaporation – Daytime sun and heat leads to much more wasted water due to evaporation from the lawn’s surface before it can soak in.
- Growth slowed by heat – Warm season grasses in particular do not grow well when temperatures reach above 80-85°F. Watering during peak heat does little good.
- Disease risk – Wet grass for prolonged periods, especially overnight, greatly increases vulnerability to fungal and bacterial diseases.
- Poorer absorption – Compacted soils and thatch prevent water from adequately penetrating the lawn when temperatures are hot.
- Enhanced weed germination – Tall fescue lawns sees more crabgrass and other weed sprouting when watered at night.
Additionally, evening watering may violate local regulations in some municipalities that prohibit lawn irrigation after a certain time (often between 8pm to 10pm) to conserve water.
Exceptions for Extreme Heat
During seasons of extreme heat and drought stress, the general guidance changes. When daytime highs exceed 85°F and there is little rainfall, it becomes necessary to water in the evening to replenish moisture before hot sun returns the next day.
Under these conditions, avoid watering between 4-6pm when evaporation rates are still high. The best window is between 6-10pm after the peak heat has passed but before dew forms. This minimizes water loss while giving grass a chance to absorb moisture overnight.
Adjusting the watering schedule to later in the day prevents the grass from going dormant or dying during periods of heat, drought, and intense sunlight. Be sure to water deeply and infrequently to encourage deeper rooting.
Considerations by Grass Type
The ideal watering time can also vary depending on the type of grass you are growing:
Cool Season Grasses
- Kentucky Bluegrass
- Perennial Ryegrass
- Fine Fescues
- Tall Fescue
These grasses thrive in cool, moist conditions. Avoid watering during midday heat. Continue morning watering even in droughts, just increase frequency.
Warm Season Grasses
- Bermudagrass
- Zoysiagrass
- Buffalograss
- St. Augustinegrass
Heat tolerant warm season grasses can handle occasional evening irrigation as needed to alleviate drought stress. Return to morning watering when conditions improve.
Newly Seeded Lawns
Frequent, light irrigation is crucial for the first 2-3 weeks after planting new grass seed. Apply early morning waterings in 3-5 minute cycles to keep seedbed constantly moist until sprouting occurs. After sprouting, gradually reduce frequency while increasing duration.
Watering Tips and Duration
Proper technique is just as important as timing when watering new grass:
- Water deeply – Apply approximately 1-1.5 inches per watering session to soak 6-8 inches deep into the soil.
- Water infrequently – Water 2-3 times per week, not every day. Too much moisture inhibits root growth.
- Water early – Complete all watering before 10am to minimize evaporation and allow drying.
- Adjust for rain – Skip watering after significant rainfall of 1 inch or more.
- Inspect soil – Probe with a screwdriver to check depth of moisture penetration into soil after watering.
Use an empty tuna can to help determine proper watering rates. Place the can in the lawn and measure the depth of water after a set irrigation time, adjusting your runtimes accordingly.
During the first 2-4 weeks after seeding or sod installation, new grass needs frequent light waterings to remain constantly moist. After the grass is established, gradually transition to deeper, less frequent irrigation sessions.
Impacts of Irrigation System
The specific sprinkler system you use can also influence ideal watering times. Common irrigation options include:
Automatic In-ground Systems
Permanent sprinklers installed underground on a timer offer the most convenience and precision. Schedule morning waterings before 10am to maximize efficiency.
Automatic Portable Sprinklers
Oscillating or traveling sprinklers on hoses with built-in timers still allow automatic watering at optimal times. Just position sprinklers properly each day.
Manual Sprinklers
Hand-moved sprinklers or hoses require daily action to water. Makes it challenging to water early in the AM before leaving for work. May lead to inefficient PM watering.
Establishment Methods
New lawns were either seeded into bare soil or installed as sod. Seeded lawns require more frequent light irrigation. Sod lawns need less water overall but benefit from occasional deep soakings.
Watching the Weather
Paying attention to weather forecasts allows you to adapt watering schedules accordingly. For example:
- Water extra before expected hot, dry periods
- Delay watering if chance of heavy rain
- Water in evenings during extreme heat waves
- Cut back on watering when cooler temps arrive
Installing an automatic rain sensor shut-off device prevents irrigation systems from running when not needed after storms. Being flexible with watering routines based on changing weather prevents under or over-watering.
Signs Grass Needs More Water
Look for these visible indicators that your lawn needs additional irrigation:
- Grass blades folded or rolled lengthwise
- Blue-gray color
- Footprints remain visible on lawn for extended time
- Muddy soil if grass peeled back
- Crabgrass and other weeds invading
Adjust your watering schedule to provide adequate moisture if you observe any of these symptoms of drought stress. Target watering grass in the early morning hours.
Conclusion
Watering new grass in the early morning offers the most benefits in the majority of conditions. The exceptions are during extreme summer heat when limited evening watering may be warranted. To maximize growth and health of new lawns, it’s best to:
- Water between 4-10am, avoiding afternoons/evenings
- Water deeply and infrequently
- Allow grass to dry out during daytime
- Adapt schedule based on weather and grass type
Proper irrigation when caring for young grass results in the establishment of a deeply-rooted, drought resistant lawn.
