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Do I Need A Light Meter for Growing Cannabis?

Growing Cannabis takes a lot of skill and precision to end up with a premium product. You need to make sure you have the right kind of equipment on hand to grow a perfect yield of crops.  Besides good lighting and a proper growing medium, you also should consider using tools like a digital hygrometer and a light meter. A light meter can be especially helpful in any grow room, especially if you are growing more than 6 plants.  Here are the products reviewed below:

ThermoPro TP53 Digital Hygrometer Indoor Thermometer for Home, Temperature Humidity Sensor with Comfort Indicator & Max Min Records, Backlight Display Room Thermometer Humidity Meter, LCD
BTMETER BT-881D Digital Illuminance Light Meter, Measure Lights 0.01~400,000 Lux (0.01~40,000 FC) Foot Candles Luxmeter with 270º Rotated Sensor for Plants LED Lights Indoor Outdoor Light Tester
Light Meter Digital Illuminance Meter Handheld Ambient Temperature Measurer, Range up to 200,000 Lux, Luxmeter with 4 Digit Color LCD Screen
Sekonic L-308X-U Flashmate Light Meter (401-305) with Deluxe case
Dr.meter LX1330B Digital Illuminance Light Meter, 0-200,000 Measurement Range Lux Meter
ThermoPro TP53 Digital Hygrometer Indoor Thermometer for Home, Temperature Humidity Sensor with Comfort Indicator & Max Min Records, Backlight Display Room Thermometer Humidity Meter, LCD
BTMETER BT-881D Digital Illuminance Light Meter, Measure Lights 0.01~400,000 Lux (0.01~40,000 FC) Foot Candles Luxmeter with 270º Rotated Sensor for Plants LED Lights Indoor Outdoor Light Tester
Light Meter Digital Illuminance Meter Handheld Ambient Temperature Measurer, Range up to 200,000 Lux, Luxmeter with 4 Digit Color LCD Screen
Sekonic L-308X-U Flashmate Light Meter (401-305) with Deluxe case
Dr.meter LX1330B Digital Illuminance Light Meter, 0-200,000 Measurement Range Lux Meter
$11.99
$39.99
$25.99
$214.95
$34.99
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713 Reviews
2,259 Reviews
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ThermoPro TP53 Digital Hygrometer Indoor Thermometer for Home, Temperature Humidity Sensor with Comfort Indicator & Max Min Records, Backlight Display Room Thermometer Humidity Meter, LCD
ThermoPro TP53 Digital Hygrometer Indoor Thermometer for Home, Temperature Humidity Sensor with Comfort Indicator & Max Min Records, Backlight Display Room Thermometer Humidity Meter, LCD
$11.99
-
-
BTMETER BT-881D Digital Illuminance Light Meter, Measure Lights 0.01~400,000 Lux (0.01~40,000 FC) Foot Candles Luxmeter with 270º Rotated Sensor for Plants LED Lights Indoor Outdoor Light Tester
BTMETER BT-881D Digital Illuminance Light Meter, Measure Lights 0.01~400,000 Lux (0.01~40,000 FC) Foot Candles Luxmeter with 270º Rotated Sensor for Plants LED Lights Indoor Outdoor Light Tester
$39.99
713 Reviews
Light Meter Digital Illuminance Meter Handheld Ambient Temperature Measurer, Range up to 200,000 Lux, Luxmeter with 4 Digit Color LCD Screen
Light Meter Digital Illuminance Meter Handheld Ambient Temperature Measurer, Range up to 200,000 Lux, Luxmeter with 4 Digit Color LCD Screen
$25.99
2,259 Reviews
Sekonic L-308X-U Flashmate Light Meter (401-305) with Deluxe case
Sekonic L-308X-U Flashmate Light Meter (401-305) with Deluxe case
$214.95
-
-
-
Dr.meter LX1330B Digital Illuminance Light Meter, 0-200,000 Measurement Range Lux Meter
Dr.meter LX1330B Digital Illuminance Light Meter, 0-200,000 Measurement Range Lux Meter
$34.99
-
-

Temperature,Humidity and Light Measurement

Indoor cannabis growing requires a room to be set at a certain temperature. The same goes for the humidity in the room. If the temperature is either too cold or too hot then your plants can experience a plethora of problems. Diseases can set in, spider mites can breed or your plant yield can be less than planned for.

Because the intensity of the light you use affects the temperature and humidity, let’s start with how to monitor those factors in conjunction with designing the ideal lighting arrangement.   Here’s a good and inexpensive temperature and humidity monitor:

8%
ThermoPro TP53 Digital Hygrometer Indoor Thermometer for Home, Temperature Humidity Sensor with Comfort Indicator & Max Min Records, Backlight Display Room Thermometer Humidity Meter, LCD
  • Informative Temperature Gauge: Thermometer with humidity monitor displays and stores all time/24 hours Max & Min records; The air comfort indicator helps you get the comfortability of your home at a glance
  • High Accuracy & Fast Refresh Rate: Hydrometer digital is equipped with an advanced temperature sensor and accurate to ±2.0°F(±1.1°C) and ±2–3%RH, which refreshes every 10s to promptly instruct you to adjust humidistat
  • Touch Sensitive Backlight: Temperature humidity monitor features a touch backlight button on the sleek, narrow bezel directly below the clear display, to easily turn on the backlight in dark conditions
  • Multiple Placement Options: Wall thermometer indoor is designed with tabletop stand, hanging mount and strong-magnetic back, which allows you to conveniently attach or place the digital humidity gauge wherever you desire
  • Wide Usages: Home temperature monitor ensures proper temperature and humidity control, benefiting your skin and health; Room temperature monitor can be used in baby room, nursery, cellar, basement, warehouse, greenhouse and etc.

Why Do I Need a Light Meter Too?

To help keep the temperature straight and measure how much light your plants are getting, lots of expert indoor growers use a light meter along with their grow lights.  A light meter helps you determine if you have enough light in your room, if your plants are close enough to your lighting system or if you have enough lighting in some places and not enough in others.

If you suspect your planting area has uneven lighting, with plants on the outside looking less robust than plants in the middle, a light meter can let you know the facts before you buy another grow light or rearrange your space.

Like grow lights there are many light meters available on the market and prices range from cheap to outrageous.

Editor’s Choice for Light Meter

The Digital Light Meter LX821 is great for use in greenhouses, hydroponic growing, indoor grow rooms, and for performing light audits. It is well-rated and has everything you need for your indoor grow.  It’s not the most expensive but it’s also not the cheapest, and that’s a good reason to prefer it.

Professional Digital Light Meter LX821 for Greenhouse, Hydroponics, Gardening, Architecture, Lighting Audits
  • Digital Light Meter for sun light, fluorescent light and grow lights, such as metal halide lamps
  • Great tool for hydroponics and greenhouse use, growers make sure all plants receive the right amount of light
  • Measures in Lux and Footcandle, 4 ranges, up to 200,000 lux or 20,000 FC
  • More precise than most other light meters: Accuracy ±3% Repeatability: ±2%
  • Battery: Standard 9V, included

Here are some of the highlights of this particular light meter:

  • This Digital Light Meter works great for measuring sunlight for outdoor plants. The sun’s rays can change during different times of the day. So if you have delicate plants or flowers growing outdoors this meter will measure the lumens being output by your lighting system. If the measurements are off, then you can bring your plants indoors or cover them. This works well for measuring sunlight coming through a greenhouse with see-through windows or walls. If you are using indoor fluorescent light or other grow lights, such as metal halide lamps this meter works fine with those as well.
  • Hydroponic grow rooms use water systems to grow indoor Cannabis and other delicate plants. They too must use special lighting to help them grow. This light meter works with hydroponic systems. You can use the meter to see if your lighting isn’t too hot to affect the water temperature. If the water temperature changes it can affect plant growth.
  • This meter measures in Lux and Foot-candle. It has 4 ranges, up to 200,000 LUX or 20,000 FC. It is more precise than some other light meters with an accuracy level of plus or minus 3% and repeatability of about 2%.
  • It is battery operated so you don’t have to worry about needing another electrical outlet. It uses a standard 9V battery which comes included in the packaging for convenience.

This is a professional light meter. It is easy to use and it works well in any setting. But to be perfectly clear, any reasonably accurate light meter will work as long as you use it regularly and keep track of where you are recording levels of light.  So whether you are using it for small grow tents or at large nurseries, your plants will benefit from its use.

How to Use a Light Meter

Any light meter is very easy to use. Simply turn it on in your growing room area. Then place it in several areas to get an accurate reading. Your highest reading will always be right under your light systems. Place it around various corners to see if corner plants are getting enough light. The plants directly under the lights should be checked more frequently as they get the most light exposure. Depending on your light set up you may have to either raise your lights away from the plants.

Why is Light Level Important

Cannabis likes the sun but not too much and nor for too long. You need to be accurate with lighting. There are different stages for growing Cannabis and each one needs a certain amount of light. Too much lighting at an early stage can cause unusual growth. Or you may end up with burnt plants. If you have several plants you may need to add in more lighting if the meter determines that you don’t have sufficient light in the grow room area.

For first-time or beginner Cannabis growers, it is important to learn how much light is needed at the various growth stages, starting with seedlings or cuttings. Here is MaryJane Farmer’s article on various lighting schedules or “recipes” for the different stages of plant growth. Advanced users should already know this and will easily be able to determine how much light is needed. A light meter can benefit the user in both cases.

Measurement Range

Different light meters can track and measure different ranges of light output. A professional-grade light meter like our Editor’s Choice has a high upper range of up to 200,000 LUX. Therefore, it can measure intense bright light such as that from using metal halide lights in a grow room. It is also frequently used in measuring lighting in hydroponic systems and with direct sunlight.

Temperature, Humidity and Light = Quality

Our Editor’s Choice digital light meter has a higher accuracy than some others and that is one reason people love to use it for their grow rooms. But for most purposes, as long as you measure regularly and keep a record of your measurements using the same meter, you will soon have the information you need to determine whether your lighting setup is right for your grow space and for your plants.

Cannabis growers know that their plants must be grown correctly otherwise the end product will not turn out right. Just like the temperature setting, the humidity levels and lighting need to be adjusted for an optimal grow process to flow smoothly. Any glitch in the process can affect the product in a negative way. So using tools like a digital light meter is highly recommended for any plant grower.

Last update on 2023-02-20 / Affiliate links / Images from Amazon Product Advertising API

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