Does Grass In Full Sun Need To Be Watered Differently?

Lawn watering can be quite a source of contention these days. Between concerns over high utility bills and local restrictions during times of low rainfall, you certainly don't want to use your sprinkler more than you need to, yet you want to give your yard the best chance at growing strong. You want to apply enough water for proper maintenance of the lawn, which, as a general rule, is between 1 and 1.5 inches per week, whether it's from rainfall, sprinkling, or a combination of both. However, does this amount change for portions of the lawn that are in full sun versus being primarily shady? 

As you might expect, grass that's in highly sunny areas of the yard needs more water than those blades that are in the shade. Typically, you want to give the entire lawn the recommended amount of moisture per week and then give the sunny areas a little extra moisture. Overall, sunny areas may need up to 1 inch more of water than shaded areas.

However, you may need to adjust these amounts based on the weather and the time of year. For example, if you have a week where the weather is cloudy, for example, you may not need to water as often because of the extra protection from the clouds. Additionally, grass tends to need more water during the hottest parts of summer from June through August, and a little less moisture in the seasons of spring and autumn.

Having a yard with clearly delineated areas of full sun and heavy shade can create challenges for a homeowner. Many landscapers even recommend that you plant different strains of grass seed in sunny areas of the yard versus the shady areas. This different treatment applies to watering, too. There are a number of reasons that the sunny sections of the yard need more moisture from sprinklers than areas that receive protection from shade.

Because of evaporation, the sun will heat up and dry out the soil much faster in areas of the lawn that do not have shade versus areas with protection. Drier soil needs replenishing from the sprinkler more often to keep the yard thriving and growing. Although the air temperature is the same in the shady areas and sunny areas, the solar radiation is heating everything more in the portions of the yard that don't have protection from trees. 

When watering the areas that have significant sun exposure, it's also important to remember that if you use the sprinklers during the middle of the day, evaporation will affect the amount that actually reaches the plants and the soil. You could lose anywhere from 25% to 50% of the sprinkler's water through evaporation at midday. Try to water before 10 a.m. or between 4 p.m. and 6 p.m. to avoid evaporation while benefiting the lawn as much as possible.

You might think that if your lawn is primarily shaded from trees, you maybe can greatly reduce the amount of water you need to use or that you can skip running your sprinklers at all. However, this is not exactly the case. Although shady areas will lose less moisture to evaporation than sunny areas, they still can lose some moisture, as they are likely to receive sunlight at certain times of the day. Additionally, the tree canopy may block some rain from reaching the grass. Tree roots can grab some moisture meant for the grass roots, too. 

Overwatering is a common mistake with lawns, which further complicates the process of trying to give the grass in shady areas the amount of moisture that it needs. Try to stick to a basic routine of sprinkling a couple of times a week for 30 minutes per section across the entire property. Then add water to sunny areas as needed, based on weather and the season. A deep watering a couple of times per week should give the root system the strength it needs to survive those times when drought and local restrictions on watering take hold. If you're struggling to apply the right amount of water, set out measuring cups or empty food cans at a few spots on the lawn. Then measure the amount of water that they catch during sprinkling over a period of 30 minutes.