10 Instruments Every Grower Needs

By Chris Bond
Published: December 27, 2016 | Last updated: April 8, 2021 09:23:13
Key Takeaways

Growers can never have enough information to gauge the state of their plants. From auxanometers to brix meters, the more beta the better. Chris Bond recommends 10 instruments hobby growers and commercial growers alike should keep handy.

Beyond the basics of soil, seeds, pots and trays as well as trowels and watering cans, there are several devices that plant growers should have in their arsenal.


Most are necessities that even hobby growers should have while some are probably better suited for growers who produce crops for sale. Regardless of your level of production, the following 10 items should be added to your want-list right away.


This one probably goes without saying, but a thermometer is among the most basic of instruments any grower should have. There should be a thermometer in every separate growing area whether there are currently plants under production or not. It is important to take note of temperature variations within your growing space over the course of the day and year to know when it is most suitable for your crop of choice to grow best.


Thermometers can, of course, be extremely basic instruments or have other measuring devices on them. The more you know about the particular climate of your grow space, the better. Consider obtaining a thermometer that also provides information on the humidity as well. Many of these devices are able to be viewed remotely and also record up-loadable data for later analysis. From an old-fashioned bulb-type to a high tech wireless gadget, no grow space should be without a thermometer.

Read also: The Best Temperatures for an Indoor Grow Room

pH Meter

Like thermometers, pH meters run the gambit of sophistication. Expect to get what you pay for with these. Check product reviews and do your homework. Different pH meters measure using different methods, but all are meant to tell you what thepotential of hydrogen (pH) of your growing media is. This is important for any grower to be able to monitor so they can make informed decisions about what amendments to add to their media in order to avoid nutrient deficiencies or toxicities in their plants.


The pH scale indicates the acidity (pH below 7.0) or alkalinity (pH above 7.0) of a substance, usually in liquid form. This is pertinent information for a couple of reasons. Not all plants thrive at the same pH level. It would be unreasonable to expect to use the same growing media for all types of plants and achieve optimal results.

The other reason it is useful to know the pH of your media is that not all nutrients are available to your plants at all pH levels. The nutrients may be present in the soil, but are essentially locked out and not able to be utilized by your plants at certain pH’s.


The pH of any media is also not necessarily constant. They are affected by the plant’s needs, the pH of the irrigation solution and of course the media itself. Plan on routinely testing the pH of your growing media throughout the year to obtain better yields and healthier plants.

Read also: Perfecting the pH of Your Hydroponic Nutrient Solution

EC & TDS Meters

Electrical conductivity meters (EC) and total dissolved solids (TDS) meters both measure the amount of fertilizer in your irrigation water or media. An EC meter will measure how much current a solution carries as read in milli- or micro- Siemens (m/S). Pure hydrogen and oxygen should not carry current, therefore any other substances, usually fertilizer salts in the water, can be measured.

The TDS meter will measure the number of particles in the solution, either in parts per million (ppm), parts per thousand (ppt) or milligrams per liter (mg/l). Pure water should have zero, so the TDS will tell the user how much fertilizer solution is in the irrigation water.

Read also: Understanding EC, TDS and PPM

Fertilizer Injector

Fertilizer injectors can be as basic as a syphon in a bucket of stock fertilizer solution that adds an approximate amount of fertilizer to a stream of irrigation water or a more sophisticated device that can deliver a specific ppm of a stock solution into a drip, overhead, mist or hand-watering system. It important to check your math skills before running an injector system as it is easy to apply too much or too little if you are not careful.

Check with the guidelines of the individual manufacturer of the unit, but essentially to calculate the settings on an injector, multiply the desired concentration of the fertilizer in ppm by the dilution factor.

Then multiply the percentage of the primary element in your particular fertilizer, usually nitrogen (N) by a conversion constant (C). The conversion constant varies based on the unit of measure. For ounces per US gallon, C is 75. For pounds per US gallon, C is 1,200. For grams per liter, C is 10.

The product of C multiplied by the element percentage is what the product of the concentration by the dilution factor is divided by. There are many online calculators to help with this formula. Knowing how to calculate accurately will help to deliver consistent fertilizer amounts to your crops whenever they need it.

Nutrient Meter

A nutrient meter is a generic term for any number of devices that can measure specific quantities of nutrients. Most commonly, nitrogen, phosphorus, potassium, calcium and magnesium are measured, but there are meters for the micronutrients as well. Sometimes referred to as a “fertometer” these meters are particularly helpful to know what specific nutrient levels are during key phases of plant development. Plants use different nutrients at differing quantities during their various stages of growth, blossoming and fruiting. A nutrient meter will help to ensure you are able to give your crop what it needs, when it needs it.

Water-Quality Testing Kit

This, too, is somewhat of a generic term as there are numerous tests for different characteristics of water. There are quality tests for not only potability, but for suitability for irrigation. Water tests can tell what particular hardness levels are, which is especially important for growers using well water as opposed to city water. Other tests will reveal levels of physical and biologic contamination.

Still others look at the presence of heavy metals. If you are unsure which test kit to obtain, it is easy to get a lab analysis of your water performed. Once this comes back, areas of concern should be closely monitored and this will inform you on which type or types of water-quality testing kit to obtain.

Read also: Water Quality Issues and How to Deal with Them

Automatic Ventilation

The correct pH, nutrient levels, moisture and water quality will not save your crops from cooking in an overheated growing area. Those who grow using natural light in a greenhouse setting are probably familiar with this danger, but even artificial grow lights can generate an excess amount of heat. An automated ventilation system of some type can help to reduce the chance of building up excess heat in your growing area and possibly killing your plants.

Like many of the other instruments and gadgets mentioned thus far, these can be relatively simple devices or elaborately wired instrumentation arrays. Simple devices are non-electrical and rely on a substance such as wax heating up and releasing some type of spring, which can then push open a vent or curtain to let out some of the heat.

Other ventilation systems may rely on sensors that communicate with motor-driven curtains, vents, doors or windows to open and close depending on the temperature. Still others can be programmed to call a telephone number to alert by text or message that there is a condition in a growing area that needs to be addressed.

Read also: How To Perfect Your Grow Room’s Ventilation System

Light Meter

Light meters, or photometers, are useful to determine if a growing area receives enough volume of light as well as usable light for optimal plant growth. This is helpful when deciding where one should grow specific types of crops depending on their respective light needs and whether or not supplemental grow lighting should be utilized to make up for any limitations of the grow space in regards to lighting.

Brix Meter

The brixscale is the measure of the sugars in any plant or fruit sap. The test, actually performed by using a refractometer, measures the amount of light bent when passing through the sap. This is important for a grower to know as it directly relates to plant health and taste. The higher the value on the brix scale is, the stronger the plant and the sweeter the fruit or vegetable. Knowing the brix value of one’s crops is useful not only for marketing purposes, but useful to determine the effectiveness of any fertilization program or judging the results from the addition of various nutrients to your crops or media.

Read also: Building up the Brix for Healthier, Nutrient-Dense Crops


An auxanometer is for the serious grower who wants to be able to track the sum of all of his or her efforts into a crop or plant as well as growth spurred by changes in the environment. This device measures the growth rate of plants.

Depending on its sophistication it can measure rapid responses to a growth stimuli taking minutes or even seconds or only slower responses of hours or days to growth stimuli.

Use of an auxanometer is usually reserved for researchers and academics, but a serious grower could benefit from being able to note what actions he or she takes in the care of their crops that have immediate and measurable reactions.

Read next: pH Balance for Efficient Nutrient Uptake


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Written by Chris Bond | Certified Permaculture Designer, Nursery Technician, Nursery Professional

Profile Picture of Chris Bond

Chris Bond’s research interests are with sustainable agriculture, biological pest control, and alternative growing methods. He is a certified permaculture designer and certified nursery technician in Ohio and a certified nursery professional in New York, where he got his start in growing.

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