Is Overwatering Costing You?
Are you overwatering? Follow these tips for reducing water usage and growing healthier crops.

by Michael Kovalycsik, National Sales & Marketing Director, Delta T Solutions


Soil moisture sensors can be helpful in determining a crop’s irrigation needs to avoid costly overwatering.
Soil moisture sensors can be helpful in determining a crop’s irrigation needs to avoid costly overwatering. Photo: Costa Farms, N.C./Rough Bros. Greenhouse


It makes good business sense to reduce water use no matter where you are, but in California, it’s an absolute necessity. This year has been one of the driest on record, with the state seeing less than 60% of average precipitation for the water year, according to the California Department of Water Resources.


4 Tips for Improving Water Efficiency

Courtesy of Dr. Marc van Iersel

1. Keep track of water use. If you don’t have them, install water meters. If you do have them, make sure to keep a record. The first step to more efficient irrigation is knowing how much water you use.

2. Test the uniformity of your irrigation system. If uniformity is poor, it will be practically impossible to irrigate efficiently.

3. Measure the leaching fraction. If you have good quality water and fertilize appropriately, very little leaching is needed.

4. Measure how much water your plants use. To do this, water thoroughly and let the pot drain. Then weigh and weigh again after 24 hours. The decrease in weight is the water use. Do this both on sunny and overcast days to see how important light levels are. If you know the output of your irrigation system, you can use this to determine how long you need to irrigate to replenish the water used.

“The vast majority of growers overwater, which can actually be very expensive,” says Dr. Marc van Iersel, professor, plant nutrition and physiology in the Department of Horticulture at the University of Georgia. “But because underwatering results in symptoms that show up quickly, many growers feel that overwatering is the safe way to go.”

In addition to the cost of running pumps, overwatering can cost growers in the form of plant loss due to disease, additional fungicide use and fertilizer leaching. “Because many of the detrimental impacts of overwatering occur slowly (e.g. disease), many growers don’t see the direct link between overwatering and disease,” says van Iersel.

He recommends asking yourself the following questions to calculate how much overwatering may be costing you:

  • How many plants are lost to disease?

  • What is the cost of fungicide applications to keep root pathogens under control?

  • How much is spent on fertilizer? (In many cases, 50% of the fertilizer is washed out of the root zone and lost.)

  • How much does the water itself cost (including the power to pump it)?

In addition, using soil moisture sensors can be extremely helpful in determining a crop’s water needs, because “they provide an objective measurement of the water status of the substrate,” says van Iersel. “Having those data at your fingertips helps to make better decisions about when to water and how much to water. And, in many cases, such sensors can be integrated into greenhouse control systems and be used to automatically irrigate when needed.”

Delta T Solutions has designed and manufactured customized heating solutions for greenhouse growers using hydronic (hot water radiant) heat for 30 years. To learn more about cost-effective in-ground bench and perimeter heating systems; high-efficiency boiler systems; and other systems that improve crop health, contact Delta T at 800-552-5058 or email


Delta T Solutions
27711 Diaz Rd, Suite B, Temecula, CA 92590 • 800.552.5058 • 760.682.0428 (fax) •