Take Back Control of Your Growroom!

By Steve Cather
Published: October 1, 2015 | Last updated: December 7, 2021 11:07:13
Key Takeaways

Growers must rely on their senses—common and otherwise—to pull off massive yields, but our senses alone aren’t always perfect when it comes to determining what needs altering in our indoor gardens. Thankfully, there are growroom controllers available to lend a hand. Single- and multi-purpose growroom controllers will do the work in your garden you either don’t have the time for, don’t have the patience for or just simply want to automate.

Source: Stuart Key/

As humans, we tend of think of ourselves as being pretty reliable. We wake up and make it to work on time every day, mostly. We can tell what the temperature is in our living rooms, sort of. I can probably tell the difference between 10% humidity and 80% humidity, though admittedly I can’t tell the difference between 45% and 65% humidity.


A human’s internal sense of timing and environmental sensors would not pass muster when compared to the accuracy of a clock or a thermometer. Human fallibility and unpredictability are two of the major causes of garden problems. With these concerns in mind, let’s look at several types of growroom controllers and see how they may benefit you.

Most people are familiar with the timers that control their lawn sprinklers and the thermostats that run their household HVAC systems. In addition, your household possibly already has a lamp timer that you bought to fool thieves into thinking you’re home when you’re away on vacation.


These are a few examples of some products you may be using to automate simple processes in your home. The good news is that all of the aforementioned tools have analogs designed just for your growroom. Each of these devices will do the work you either don’t have the time for, don’t have the patience for, or just want to automate.

The majority of the controllers you see at your local shop come with a cord that plugs into the wall and at least one integrated receptacle to plug your devices into. Depending on the controller, you may be able to control lights, fans, pumps, humidifiers, dehumidifiers or CO2 equipment.

More advanced control devices may have a dedicated receptacle on the controller for each piece of equipment. There are two primary types of off-the-shelf control systems indoor gardeners need to be aware of—single-purpose and multi-purpose—both of which you are likely to find at your local shop.


Single-purpose Controllers for the Grow Room

Single-purpose controllers are the entry-level workhorse units most people buy one at a time as the need arises. They are devices born of necessity and ingenuity. Your lamp timer would be considered a single-purpose control system.

The humble timer has one job. You rely on it to turn the light on and off at specified intervals. Single-purpose controls handle timers, thermostats, humidistats and CO2 delivery devices. When choosing a timer for your lights, choose a unit with the appropriate electrical rating.


A cheap lamp timer from a big box store may create a safety hazard. Spend a little money just to be safe. Smaller devices such as pumps can be operated on a less-expensive timer with no problems. If you are unsure of what to buy, seek the advice of a knowledgeable salesperson at your local indoor gardening store.

Indoor garden thermostats will usually have a power outlet into which you plug your choice of devices. Rather than just plugging in an air conditioner or heater, you may choose to tie your thermostat to a ventilation fan, oscillating fan or other gadget. A temperature-sensing outlet is handy in both the winter and summer.

In cold weather, you have the option of letting your lights provide a little heat for your garden. Simply plug your ventilation fan into the thermostatically controlled outlet and set the temperature. When your room warms up to the pre-set level, the fan will come on and begin sucking the hot air out. When the temperature drops below your set point, the fan will turn off. This can operate in the reverse as well.

In the summer, your fan will stay on all day and turn off automatically when the temperature drops to your desired set point. This self-regulating system simplifies your life by acting independently while you tend to other matters. A thermostatically controlled ventilation fan can mean the difference between a bumper crop of peppers and a crispy little bush covered in roasted jalapenos. It can also make the difference between a burned-out gardener, and one with time to spare.

A humidistat is another useful, single-purpose device that gardeners use. A humidistat measures the humidity in your room and turns your fans, humidifier or dehumidifier on or off. Keeping your humidity in the proper range has a number of direct impacts on your plants. The growth rates of pests, molds and mildews are affected by the room’s humidity levels.

A succulent garden growing in a highly humid environment will rot. A tomato plant will dry up in days when subjected to extremely low humidity levels. By making use of these widely available tools, you will have much more control over the growing environment. Plug a ventilation fan into a humidity sensor and when the levels are out of range, your controller will turn the fan on or off as you select.

Multi-purpose Controllers for the Grow Room

A multi-purpose controller can range from the mild to the wild. At the lower price point are controllers with as few as two set points. More advanced systems may feature as many as six or eight functions with options galore.

The lower-priced units probably have knobs or switches to turn when choosing your desired settings. A top-of-the-line unit may have a touchscreen or a USB port to connect your laptop to. Which one is right for you? Well, that depends. Are you a small-time hobby grower with two or three lights? Or are you a large-scale grower with multiple rooms? Do you do this for a living? Or are you just supplementing your diet with leafy greens?

The more affordable multi-purpose controllers will run you somewhere in the range of $150-$450. The higher-priced units with all the bells and whistles can cost $1,000 or more. At the extreme top end would be commercial systems designed to run entire buildings that have 200 independent channels taking readings from all over the facility. These can cost $40,000 or more. Thankfully, home gardeners can obtain similar equipment for a fraction of the cost.

The logical progression for a gardener experienced with several basic automation devices is to step up to a growroom controller equipped for an entire room. A multi-purpose growroom controller may allow you to use a single device to control your lights, ventilation fans, circulation fans, pumps, humidity, heaters, air conditioning, CO2 and more. A single point of control can simplify your life by streamlining your systems and integrating your management capability.

There are a wide variety of growroom control systems out there that allow home growers to advance their skills, evolve their understanding, create repeatable results and save bushels of time. What more could you ask for? You can start small and build up to a higher level of automation, or you can design a complete growroom with a controller integrated into the design right from the get-go. Regardless of which path you choose, with growroom controllers you can be confident your investment in automation will pay dividends for years to come.


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Written by Steve Cather

Profile Picture of Steve Cather
Steve Cather, an HCI-certified cryogenics technician and gasfitter living in Boulder, Colorado, is the CEO of the Colorado-based group of gas-monitoring specialists, Sensor Compliance LLC. He is also a co-founder and the former chief of engineering at Multiponics LLC. Steve is a facial-hair enthusiast, truth seeker, independent thinker and autodidact.

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