by Elizabeth A. Tomlin
If you’re a greenhouse owner or manager, and you don’t know about e-GRO (Electronic Grower Resources Online), then you’re in for a pleasant surprise.
In a webinar sponsored by American Floral Endowment (AFE), W. Garrett Owen of Michigan State University, along with Josh Henry and Brian Whipker of North Carolina State University, presented information on nutrient monitoring made easy and floral and vegetable nutritional fact sheets made available at your fingertips.
Eastern Michigan floriculture outreach and research specialist Dr. Garrett Owen introduced the new monitoring website, www.fertdirtandsquirt.com, for in-house monitoring of greenhouse, floriculture and vegetable transplant crops.
“When we walk into a greenhouse…the majority of the time we come into contact with nutrient disorders of greenhouse crops, either it being low or high pH or EC,” explained Owen. This resulted in developing the new monitoring nutritional website.
This horticultural website has been designed so that it is also viewable from a tablet or phone, making it handy for trouble shooting in the greenhouse.
Instructional guides and videos are currently available through this site, including different monitoring methods and sampling procedures, crop specific fact sheets outlining ideal pH and EC (Electrical Conductivity) values, optimal fertility rates and photos. A searchable crop database, using common scientific names, provides recommended pH and EC values. The site also provides links to other information.
Annual bedding plants, perennials, vegetable and herb fact sheets will all be included on the site, with other additions, including strawberries and hydroponics, upcoming in the future months. Fact sheets for cannabis production will not be included on this site.
English standard measurements and metric measurements will both be available.
Henry provided information for the PourThru method to monitor substrate pH and EC.
“The PourThru method is a quick, easy and accurate way to monitor your plants’ nutritional needs,” said Henry. “It can help you to determine if your plants’ nutritional needs are being met properly.”
A ‘PourThru’ kit requires a pH/EC meter (separate or combined), pH/EC calibration solution, small jars or vials, saucers, small plastic cups, a bottle of distilled water and a box, which is not required, but can be useful.
“First,” Henry explained, “you’re going to want to start off by irrigating the crop to ensure that the substrate is extremely well saturated.”
If you are currently using a constant liquid feed fertilization regiment, irrigate as usual. However, if you are using periodic feedings, irrigate with clear water and conduct the PourThru test a day prior to fertilization, with a second PourThru the day of fertilization.
Step 2 requires placing the plants to be tested in saucers and allowing them to drain for 30 to 60 minutes after the initial irrigation.
Henry advises using a minimum of five cell packs or plants per crop to get an accurate reading.
“It’s very important that you randomly select plants from throughout your crop. You want to go to the interior of the bench. Pick plants from the middle and the back.” This will give you a true idea of how the crop as a whole is actually doing. “And additionally, it’s important that you select crops for different pH and EC requirements.”
Step 3 requires that distilled water is added to the substrate. “It’s very important that you are very patient and that you do not add too much water.” Adding too much water will give an inaccurate EC value.
For a cell pack or 4-inch pot, about one ounce of distilled water should be used. Use 2.5 ounces would for a 5- to 6-inch pot. Use 3.4 ounces for a 6.5 inch or larger pot.
“These are just initial values to go by. It’s very important to know that the volume that you want to add to the pot can vary from pot to pot, crop to crop. Different types of substrates have different properties.”
Other factors, including root size, will affect how much distilled water is used and how quickly the leachate is available for testing. Again, Henry advises patience when conducting the testing procedure.
In step 4, leachate that has been displaced is collected from the saucers.
“If you collect too much, it will dilute your EC, which will indicate that you have really low soluble salts. And if you collect too little leachate, you are going to have really high EC ratings saying that you have really high soluble salts. So, it’s really important that you collect a consistent amount of leachate per pot and keep your measurements consistent as you go on.”
You should be collecting about the same amount of leachate as the distilled water that you added to the plant, meaning one ounce added to the pot would equal one ounce collected.
“It’s also very, very important that you calibrate your meters each and every day that you are doing sampling. It’s also very important that you never pour used solution back into the original bottle, as that can distort the values and potentially contaminate your calibration solution.”
Step 5 consists of calibrating your meters. Keep in mind that calibration protocol can vary depending on your individual meter.
In step 6, recording and documenting your pH and EC value readings will be done.
Henry advises having a clipboard handy and, if possible, waterproof paper. “I can’t tell you how many times I have actually spilled leachate all over my paper and had a really messy time with it.”
In step 7 you will evaluate the measurements and data. A spreadsheet with dates and other important information (crops, pots and cultivars sampled, visual symptoms, bench numbers, etc.) is valuable for evaluating measurements of pH and EC values.
“Again, I can’t stress this enough,” commented Henry, “it’s very important that you sample five pots or cell packs per crop, and that these are randomly selected from throughout the crop so that you can get a better picture of how your crop is doing nutritionally.”
Crops should be tested soon after potting and on a regular two-week schedule thereafter. Crops with visual symptoms should be tested sooner.
“Monitoring with the PourThru method can help you to prevent pH and EC problems before symptoms occur, to help you keep a nice healthy crop throughout the entire growing season.”
Dr. Brian Whipker said that a distinct advantage of the PourThru testing method compared to other testing methods, is that it is non-destructive to the root system of growing plants. “And, actually, you’re going to find it’s quicker, it’s twice as quick, if not three times as quick.”
Whipker explained the new free GroZone Tracker, found at grozonetracker.com or under the mobile app option at the e-GRO site.
“This works for both nursery crops and greenhouse growers,” said Whipker.
For more information email Dr. Whipker at email@example.com.