CO2 levels

by Jerry Morse
(Vicksburg, MS USA)

Is there a gauge I can use to check the CO2 levels in the room where I am growing plants? Is there a magic number that relates to CO2 levels?

Answer: Jerry- the device you are referring to is known as a CO2 monitor. After a little checking, most of the monitors I saw cost around $500 and up, although a couple were cheaper. These include both hand held monitors as well as "wall mounted" monitors that also control your CO2 equipment.

Personally, I wouldn't spend any money on CO2 unless all other factors in your garden have been made ideal first. My page on plant growth and CO2 describes in detail how to calculate the desired CO2 levels and manage your system with just timers....otherwise you will have to purchase a CO2 monitor at least.

Natural CO2 in the atmosphere is around 400 ppm. When the level in your garden drops below 250 ppm, photosynthesis (plant growth) stops. Simply running an exhaust fan and supplying fresh air is enough to prevent this, but some people have noticed an increase in plant growth with an increase in CO2 levels.

If you are able to prevent your garden area from being constantly exhausted (usually by adding air conditioning), you may be able to benefit from added CO2. I rarely see people aim for a CO2 level less than 1000 ppm. 1000-1200 ppm is the target level I see used most often. Much less often I read about a few people using 1500-2000 ppm.

As I said before, you are not likely to notice the extra growth unless you are starting with a healthy, problem free garden to begin with (or unless you have a lot of gardening experience). Be sure to read that page on CO2 I linked to above, and Happy Growing!