Monitoring For Better Plant Health: Media pH and EC

What Should I Look For In A pH and EC Meter?

  • Auto-shut Off: Battery-saving feature
  • Accuracy And Resolution: Accuracy should be around ±0.02 and resolution at 0.01 pH units.
  • Electrodes: Detachable electrodes are easier to replace. Purchase a commercially prepared solution for wet-storage electrodes.
  • Calibration: Look for an auto-calibration feature. Two-point calibration is more accurate than one-point.
  • Range And Readout: Digital readouts are easier to read than analog. Range should be from a pH of 2.0 to 12.0.
  • Temperature Compensation: The automatic compensation feature measures solution temperature and pH at the same time. Standard temperature for measuring pH is 77° F (25° C).
  • Waterproof vs. Water-resistant: Waterproof meters are better for measuring pH directly from a hose.

EC Meters

Although many of the considerations for choosing an EC meter are the same as for a pH meter, there are some critical differences.

  • Accuracy And Resolution: Measurements should be to the nearest 0.1 mS, accuracy should be ±0.02 mS. Measurements are often in mS/cm units, but conversion may be necessary if other units are used.
  • Electrodes: Electrodes are stored dry.
  • Calibration: EC meters use 1-point calibration, but a variety of standards exists. Choose the one closest to 1.41 mS.
  • Range: EC ranges vary from low (0-199 µS), mid (0-1999 µS) and high (0-5.0 mS or 0-19.99 mS).
  • TDS Measurements: Do not use total dissolved salts (TDS) measurements for testing soil or fertilizer solutions.

*Reprinted with permission from Understanding pH Management for Container-Grown Crops, by William R. Argo and Paul R. Fisher, a Meister Media Worldwide publication.

Experienced growers scrutinize their crops for any sign of trouble. They do this because problems are much easier to address in their early stages. But it is difficult to address problems that aren’t so obvious, such as changes in pH and electrical conductivity (EC), without a preventative monitoring program in place.  

“The bottom line is you don’t have any control if you are not measuring the impact of your management actions, and you can’t make informed decisions,” says Paul Fisher, associate professor and Extension specialist in environmental horticulture at The University of Florida. “The first step in monitoring is to use your experience as a grower to visually monitor plant performance. It is also useful to have some backup data to help you determine if the basic aspects of plant nutrition are in line. If you monitor the substrate for changing trends in pH and EC, check root health and have a complete fertilizer program in place, you can diagnose 95% of nutritional problems in the greenhouse.”

Substrate-pH

Management of pH is similar to balancing a glass of water on each side of a scale. The addition or subtraction of water from one side or the other will tip the scale. In other words, healthy plants result from keeping pH levels in the optimal range for good growth, and out-of-range pH will adversely affect plant health over time.

For a majority of floriculture crops, 5.8 to 6.2 is the substrate-pH range where most micronutrients are available for plant uptake. However, some plants prefer more or less acidity, depending upon how proficient they are at absorbing micronutrients. New Guinea impatiens (Impatiens hawkeri) and zonal geraniums are good examples of greenhouse crops that grow well in high pH conditions (6.0 to 6.6).  

Substrate-pH dictates how nutrients will react in the soil. Solubility increases at low pH levels, resulting in problems with nutrient toxicities. High pH levels have the opposite effect. “Iron deficiencies are common when pH is too high,” says Fisher. “A good biological indicator crop is petunia. Marigolds and seed or zonal geraniums are indicator crops for low pH problems where you run into iron/manganese toxicities.”

Soil pH also contributes to the severity and occurrence of plant diseases, because when pH is out of range, stressed plants are vulnerable to pathogen attacks. Thielaviopsis root rot is an example of a pathogen that favors high pH conditions.

The best approach to pH management is a preventative one. Monitoring helps growers detect changes in pH trends over time and make small course corrections to keep pH at optimal levels. Although there are times when a grower must quickly lower or raise pH, this step should be reserved for when crops would be unsaleable without intervention.

Electrical Conductivity (EC)

Electrical conductivity (EC) is a measure of the concentration of dissolved salts in the substrate from fertilizers, irrigation water and substrate components. Overfertilization, low leaching rate and poor water quality all cause EC to increase. EC measurements do not indicate which type of salt is present, nor do they specify which nutrients are available for plant consumption. They do help growers decide if fertilizer applications are excessive or insufficient.

There is a direct relationship between EC and plant growth performance. “High substrate-EC levels in can be a sign of too much sodium and chloride in the water, or it can result from overfertilization,” Fisher says. “When substrate-EC is high, a soil test by a laboratory is needed to diagnose what specific ions are causing the issue (e.g., sodium from water versus nitrogen from fertilizer). Root damage often occurs at high EC levels, susceptibility to diseases such as Pythium and increases.” High levels also can be problematic when germinating seeds or rooting cuttings. Low EC levels cause stunting and chlorosis (yellowing of leaves).

“An EC meter is also useful for checking the fertilizer injectors,” Fisher says. “Information on the fertilizer bag tells you the relationship between EC and parts per million of nitrogen. Simple math tells you that if you measure the EC of the clear irrigation water and add that to the EC of the injected water, the total will equal the EC coming out of the hose. If that total is not what you expect, adjustments need to be made.” (See Checking EC For Common Blended Fertilizer and Fertilizer Salts, Table 1)

 

Monitoring pH And EC

“Every grower should purchase good quality pH and EC meters for in-house monitoring,” Fisher says. “Secondly, they should work with an Extension agent or fertilizer company to get a basic fertilizer program in place that covers all of the essential nutrients.”

Fisher also recommends a complete water test from a laboratory at least once a year, as well as weekly in-house tests of clear irrigation water and injected water. Growers need to test major crops about every two weeks so they can take small corrective actions before plants experience too much stress.

“Information obtained from pH and EC tests is important, but visual observations are also part of the monitoring process,” Fisher says. “Observing how the crop is growing and checking the roots regularly should not be overlooked. Good growers don’t become so obsessed with lab tests and managing individual nutrients that they lose track of the bigger plant health picture.”

Leave a Reply

More From BASF...

March 2, 2015

Avoid Surprises On The Delivery Dock

A call in advance about problems with a plant shipment to a retailer you supply goes a long way toward customer satisfaction.

Read More
Janeen Wright

March 2, 2015

Deliver Plant Quality That Trumps Price [Opinion]

The industry's goal is to have loyal customers who return to the same plants time and time again, not because of price, but owing to a plant brand that shouts top-notch garden performance and is synonymous with excellence, which gives them the secure knowledge that their investment will be worth every hard-earned cent.

Read More
Heuch Pink Fizz_featured

March 2, 2015

Intergeneric Crosses Are A New Perennial Trend

Intergeneric crosses, oddities some botanists say are an impossibility, have made serious inroads in the perennial world.

Read More
Latest Stories
Health benefits of pyraclostrobin-based fungicides

July 7, 2014

Pyraclostrobin-Based Fungicides Provide Disease Control…

Take a look at the three ways pyraclostrobin-based fungicides provide additional plant health benefits, other than disease control.

Read More
Verbena estrella 'Voodoo Star.' The top row is untreated. The bottom row was treated with Pageant Intrinsic Brand Fungicide at 4 oz/100 gallons at sticking. This image was taken several days after sticking.

July 7, 2014

Want Better Rooting During Propagation? Try A Fungicide…

Research shows that fungicide use can improve tolerance to stress and increase propagation speed.

Read More
Petunias with no fungicide protection. Photo courtesy of Margery Daughtrey.

July 7, 2014

8 Tips For Getting The Most From Your Fungicides [Spons…

Cornell’s Margery Daughtrey shares advice on best practices for keeping diseases off your crops and out of the greenhouse.

Read More
Joe Lara, BASF product manager

July 7, 2014

Resistance To Change – A Grower Conundrum [Sponsor Cont…

If we’re not careful, the comfort we develop with our habits may make us our own worst enemy. This is the conundrum of conventional pest management, says BASF's Joe Lara.

Read More
Phosphorus deficiency (purpling of lower leaves) in pansies that were grown cold. Photo courtesy of Neil Mattson.

May 28, 2014

5 Tips To Diagnose A Nutrient Deficiency [Sponsor Cont…

Here's advice from Cornell's Neil Mattson on ways to properly diagnose a nutrient deficiency.

Read More

May 28, 2014

Diagnosing Nutritional Disorders In Pansies [Sponsor Co…

Yellowing, purpling and necrosis on certain parts of pansy plants point to different nutrient deficiencies.

Read More

May 27, 2014

How To Maintain A Balanced Fertility Program [Sponsor C…

It takes vigilance and frequent testing to keep plants at optimum fertility levels.

Read More
Joe Lara, BASF product manager

May 27, 2014

Plant Health, Business Health: A Convergence Of Managem…

The foundation of growing healthy, resilient plants is the culmination of well-honed horticulture skills, including the integration of various pest management techniques.

Read More

May 9, 2013

Four Foliar Diseases That Will Drive Down Profits

They say not to judge a book by its cover, but in the ornamental industry, it is the other way around. People equate plant quality with appearance. And they rarely, if ever, shell out their hard-earned money for plants that aren’t in pristine condition. Disease is one of the primary culprits in less-than-perfect-looking plants. These four pathogens, in particular, are worth avoiding in the greenhouse. Although not always fatal, these diseases will detract from crop aesthetics and make a dent in profits.   Powdery Mildew Susceptible Crops Many species of powdery mildew are host specific; others have a wide host range that includes poinsettias, roses, violas and zinnias. Symptoms Powdery mildew symptoms usually appear on the upper side of the leaves first, but they can also show up on the underside, especially on begonias and verbenas. A white, powdery growth, the result of thread-like hyphae strands and chains of spores […]

Read More

May 9, 2013

Eight Tips for Better Disease Control in the Greenhouse

The Disease Triangle: Where Growers Fit In The interaction between a susceptible host, a virulent pathogen and a favorable environment determines the severity of plant diseases in the greenhouse. Eliminate one of these three factors and you lower the probability of disease occurrence. The “human component” is an additional, but rarely talked-about factor that can be added to the disease triangle. Growers have more influence than they think on disease prevention. The management decisions they make, from the choice of cultivar to the amount of water they apply, have the potential to intensify, alleviate or eliminate conditions that favor disease. Be obsessive-compulsive about sanitation. Start clean and stay clean to prevent a majority of disease-related problems. Clear away dead plant materials, eradicate weeds, start with clean stock material and disinfect equipment and benches. Dry out. Saturated pots, water film on leaves and puddles on benches are open invitations for several […]

Read More

May 9, 2013

The Notorious Oomycetes

The oomycetes (Oomycota), also known as water molds, are a group of pathogens that play a large role in the decomposition of plants and the breakdown of organic matter. While this scenario is perfect for the great outdoors, it can cost greenhouse growers millions of dollars in yearly sales. Just as late blight (an oomycete, Phytophthora infestans) caused the devastating Irish potato famine that killed millions of people, oomycetes such as Phytophthora, Pythium and downy mildew leave a wake of destruction in their path when they run rampant in the greenhouse. Good Water Management Is Critical The name “water molds” is a bit of a misnomer. Although several species of oomycetes thrive in wet conditions, many do not. Where they were once classified as fungi, recent research shows they are more closely related to algae.“Water management is basic to controlling many of these pathogens,” says Janna Beckerman, associate professor of […]

Read More

April 17, 2013

Monitoring For Better Plant Health: Media pH and EC

What Should I Look For In A pH and EC Meter? Auto-shut Off: Battery-saving feature Accuracy And Resolution: Accuracy should be around ±0.02 and resolution at 0.01 pH units. Electrodes: Detachable electrodes are easier to replace. Purchase a commercially prepared solution for wet-storage electrodes. Calibration: Look for an auto-calibration feature. Two-point calibration is more accurate than one-point. Range And Readout: Digital readouts are easier to read than analog. Range should be from a pH of 2.0 to 12.0. Temperature Compensation: The automatic compensation feature measures solution temperature and pH at the same time. Standard temperature for measuring pH is 77° F (25° C). Waterproof vs. Water-resistant: Waterproof meters are better for measuring pH directly from a hose. EC Meters Although many of the considerations for choosing an EC meter are the same as for a pH meter, there are some critical differences. Accuracy And Resolution: Measurements should be to the […]

Read More

April 17, 2013

Strengthening Plants’ Natural Defense Systems

Thousands of years ago, plants lived their entire lives with little help from human hands. Times have changed since the advent of the modern-day greenhouse; plants are now at the mercy of the grower. While there is much a grower can do to control the environmental stresses that affect plant health, the unforeseen and unexpected still happens. At these times, it is comforting to know that the survival tactics that are an inherent part of plants’ nature are still in play today. One of the keys to minimizing environmental stresses such as pathogens, insects, drought, cold and heat may lie in strengthening plants’ natural defense systems. Natural Defense Systems Plants have developed several strategies to prevent pathogen attacks or hinder their development. Within hours of a pathogen attack, plants try to isolate the pathogen by killing off cells at the infection site, a process known as the hypersensitive response. The […]

Read More

April 17, 2013

A Drop Of Clean Water

A single drop of water can contain millions of bacteria, each one impossible to see with the naked eye. The same can be said for water in the greenhouse. What looks innocent at first glance may harbor waterborne pathogens, brim with toxic salts or have alkalinity issues. Without a regular plan in place to test water quality, how is a grower to know what he or she is really feeding their plants? Monitoring water quality is one of the first steps to better plant health throughout the greenhouse. “Testing irrigation water helps growers avoid surprises and detect changing trends so they can make small course corrections to prevent future problems,” says Paul Fisher, associate professor and Extension specialist in environmental horticulture for The University of Florida. “If you have a shallow well or water from a river or pond, testing is especially important because water quality can change throughout the […]

Read More

June 14, 2012

Disease Control And Plant Health

We’ve told you about the science behind the Intrinsic™ brand fungicides from BASF, and we’ve shared our lab research on disease control and plant health. Now it’s time to share the results of field research with Pageant® Intrinsic brand fungicide. As we uncovered benefits to plants such as tolerance to cold, heat and drought, it was time to see these at work in uncontrolled conditions like the kind growers face every day. Temperatures and other stresses are never regulated; Mother Nature’s microclimates and changeable weather sees to that. Sometimes shipping gives your plants a beating as well. As we took the plant health research to the field in 2009, 2010 and 2011, we worked with noted ornamental expert Paul Pilon of Perennial Solutions Consulting, and three growers: two in Michigan and one in Connecticut. We looked at both drought and cold tolerance, and the plant material studied included rooted liners […]

Read More

June 12, 2012

What Greenhouse Growers Need To Know About Extending Re…

Keeping plants healthy at the retailer until they’re sold is often a challenge due to weather, staffing, water and light conditions. It’s even more of a challenge for outlets where selling plants is not the main part of their business. The questions include: is there anything growers can do before the plants leave the greenhouse to extend shelf life? Do growers have a duty to educate experienced retailers about how to care for the plants on their shelves? “I think growers do have a reason to care, and they have a responsibility, but it’s a conversation that’s been going on a long time, says Dr. Terri Starman, associate professor at Texas A&M University’s Department of Horticultural Sciences. “Even if growers feel that responsibility, they don’t often have the communication [with the retailer]. When they do have that communication, it’s proved to be successful,” she says. “You hear testimonials when you […]

Read More

May 23, 2012

Keep Your Greenhouse Squeaky Clean

Diseases on greenhouse plants threaten to wipe out your most valued investment. Here's some advice on how to keep your structures clean.

Read More

May 8, 2012

Disease Control and Plant Health

Over the last several years many nursery and greenhouse growers have felt increasing financial and environmental pressure to make sustainability-driven improvements to reduce inputs —including water, chemicals and fuel — but reductions must not sacrifice plant quality. Fulfilling sustainable needs and business demands is challenging, but not impossible. Like growers, BASF views sustainability as achieving more using fewer inputs, while ensuring profitability, caring for the environment, and meeting the needs of society and future generations, in short, doing more with less. BASF research and development continually brings new innovations to market that help growers be more successful. Recent examples of this research and development include its pyraclostrobin-based product Pageant® Intrinsic™ brand fungicide. Pageant Intrinsic is the first fungicide in the ornamental market labeled for disease control and plant health. It gives growers industry-leading, broad-spectrum disease control and the bonus of plant health activity — without additional inputs. In addition to […]

Read More