Greenhouse and Nursery - Monitor your Meters

Meters used to monitor pH and salts in greenhouse and nursery media, directly, in saturate paste extracts, or in the leachates in the pour throught methods, are extremely useful management tools. However, they must be regularly calibrated, maintained properly, and electrodes need to be replaced when not performing properly. The following is a short article on the subject.

We often tell you to monitor the pH and soluble salt levels of your substrates, but growers sometimes forget to check their meters. Regardless of the quality of your equipment, the probes on these meters do have a shelf-life. You may need to replace the probe on your meter about every two years. The probes can be replaced by contacting the supplier where the meter was purchased. You should from time to time send a sample to a commercial lab for testing for comparison of pH. A unit may be off even though you are regularly calibrating your meter with fresh buffer solution (remember that these also have a shelf-life). It’s a good idea to compare your results with a commercial lab once a year. To extend the life of the soil probes make sure to keep the probe tip in buffer solution and do not allow the tip to dry out.

Modified from and article in the February 2, 2007 issue of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension