Water is a major factor in successful production of greenhouse plants. An adequate water supply is needed for irrigation, pesticide application, growing media preparation and clean-up. Plants require an adequate supply of moisture for optimum growth which is affected by many variables. A drought such as the drought during 2016 can be a challenge for some growers in MA. Many towns had water bans and some towns discouraged new plantings. Some retailers reported that the hot, dry weather also reduced demand for plants. As water supplies become shorter due to drought and over development, conservation becomes more important. Below is a list of drought and water resources for growers of greenhouse crops.
Drought Damage Assistance Program (MA) MDAR Drought Emergency Loan Fund information (2016)
Northeast Regional Climate Center (http://www.nrcc.cornell.edu/)
A weekly update of current drought information including conditions and impacts.
MA Department of Environmental Protection (DEP) Municipal Water Restrictions in MA (Map of water restrictions in MA)
Drought Effects on Water Quality for Irrigating Greenhouse Crops
Depending upon the water source, another consequence of a severe drought may be the quality of water being used for irrigation. Equipment clogged with sediment (surface water), or high salt (Na and Cl) concentration in irrigation water due to low water levels are possible considerations.
While likely sources of sodium (Na) and chloride (Cl) in the Northeast is road salt, water softeners and some fertilizers may also be contributors. High sodium acts to inhibit plant uptake of calcium, and may result in excess leaching of calcium and magnesium from the media. Acceptable levels of Na and Cl for ornamentals are less than 50 ppm and 140 ppm, respectively, however higher levels may be tolerated depending on crop sensitivity. Na and Cl can be directly toxic to plants, may contribute to raising the soluble salts (EC) level of the growing medium, or may inhibit water uptake by plants. Plant problems include injury from excess soluble salts, growth reduction, and increased susceptibility to disease. Foliar chlorosis caused by high Na and Cl is similar in appearance to that caused by deficiencies of nitrogen, iron, and magnesium. If high levels of Na and Cl are suspected as plant problems, the suspicion should be confirmed by water testing.
A 2004 study of 50 Massachusetts greenhouse growers showed that most growers were irrigating greenhouse crops with water containing safe levels of EC, Na, and Cl. However, a small, but significant number, of growers were using water containing elevated levels of Na and Cl and accompanying high EC with the result being lower quality and even crop loss. Most often this water was from a private well or pond (usually near a road), but sometimes public drinking water was the source. With the current drought, it might be helpful to have water tested and test again prior to the spring growing season to prevent any potential problems.
The solutions to the problem of high Na and Cl include regular water testing during the growing season in borderline cases of excess Na and Cl and avoidance of over-fertilization to prevent high growth medium EC; installation of water treatment systems to remove Na and Cl; efforts to protect wells and ponds from salt contamination by runoff; mix existing water sources with collected water to dilute the high salts levels or, in extreme cases, finding a new source of water.
Water Quality Resources
Greenhouse Best Management Practices (Irrigation systems, water quality)
Partial List of Water Testing Laboratories (for greenhouse water samples used by some growers)
Everris Testing Lab (http://protestinglab.everris.us.com/waterTesting.php)
JR Peters (http://www.jrpeters.com/lab-services/testing-services/nutritional.html )
Water Agricultural Lab (https://watersag.com)
Drought Tolerant Annuals and Perennials (UMass Extension)
Hand Watering Greenhouse Crops - Resources (UMass Extension)
The following fact sheets were provide by John W. Bartok, Jr. Extension Professor Emeritus & Agricultural Engineer, NRME Department, University of Connecticut.
- Is Your Water Supply Adequate
- Sizing the Greenhouse Water System
- Surface Water for Irrigation
- Protecting Your Water System with a Good Filter
- A Few Pointers for Better Irrigation
- Drilled Wells for Irrigation
- Drip Tape for Irrigation
- Subirrigation Systems