Ellen Sturup Comeau, Water Resources Agent, Beaufort County
Caption #a-rain-gauge
Sunny weather, hot temperatures, and high humidity are here! Staying hydrated is critical to staying healthy in the intense weather, and the same is true for the plants in your yard. However, did you know that overwatering your plants can lead to more issues than underwatering them? Overwatering can lead to poor root growth and a larger number of water-loving weeds like Dollar weed (Hydrocotyle spp.). Applying too much water to your landscape can also leave your plants vulnerable to fungal diseases such as downy mildew, yellow patch, or gray-leaf spot, which can be costly and/or time-consuming to treat. Not to mention that over-irrigating can also lower the availability of potable water and lead to poor drainage issues from saturated soils.
So, how much water is enough water? Luckily, South Carolina plants (including turf grasses) only need about one inch of water per week. Due to our sandy soils in Beaufort, Clemson Extension recommends applying ½ inch of water twice a week if there hasn’t been any rain. Before turning on your irrigation systems, the first thing to check is if there was enough rain to offset your plants’ water needs for the week.
An easy way to quantify weekly rainfall is to use a rain gauge! Rain gauges are inexpensive and straightforward tools. Place one in an open area, check and empty it daily, and you can calculate how much water plants have already received. If there is less than one inch of rain in a week, you can plan to irrigate. Another option to determine if there’s been enough rain is to check out the Community Collaborative Rain, Snow, and Hail Network (CoCoRaHS) program. CoCoRaHS is a citizen science monitoring effort that measures and maps precipitation. Their data is free to access and provides the same information as a rain gauge. Find a nearby station at www.cocorahs.org! However, if you cannot check rainfall amounts or a forecast, installing a rain sensor for your irrigation system can help prevent it from turning on during a rainstorm.
During weeks with little to no rain, you will have to add supplemental water through irrigation. You must calibrate your irrigation systems to ensure that you’re applying the recommended amount of water. Calibrating your system will tell you how long you need to run the system to apply ½ inch of water, how evenly your system applies water across your yard, and if you have any leaks. To calibrate your system, lay out 6-10 straight-sided containers in a random pattern around your yard and run your system for 10 minutes. Then, turn off the system, collect the cans (without spilling any water), and combine the collected water into one can. Measure the height of the water in the can and divide that number by the total number of cans used to get the amount of water your system applies in 10 minutes. You can then use this information to determine how long to run your system to apply ½ inch of water at a time.
If these directions were confusing, Clemson University – PSA has an excellent YouTube video called “How to Set and Calibrate Your Irrigation System” that demonstrates this process, and there are several fact sheets on calibrating nearly every type of irrigation system available on Clemson’s Home and Garden Information Center (www.hgic.clemson.edu). You can also always call Beaufort County Clemson Extension at 843-473-6021 to help keep plants healthy and hydrated!
Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status and is an equal opportunity employer.
