CO2

I got a book at the library the other day called "The Plant Propagator's Bible." I have always been interested in starting plants in ways other than seeds. Other than the chapter on bulb and rhizome division I won't be using much out of the book right now. The information seems well laid out and researched though so I will put it on my wish list so that when I do decide to try and divide something I will have the reference book.
It did have a few tricks for starting seedlings that I had never thought about. It mentioned that plants need carbon dioxide like animals need oxygen. Simple enough, that is 3rd grade science class. What I hadn't thought of is that in a contained area it is possible for plants to use up all of the carbon dioxide and therefore 'starve' or at the very least, get really hungry. Logically it makes a lot of sense but I had never thought much of it because I figured the fact that doors do not seal tightly was enough to let more in. I have always thought that the reason people think talking to their plants makes them grow better is because humans expel CO2 when they breathe out or talk, thereby exchanging this gas with the excess oxygen that plants provide. Always one to want to improve my garden I have decided to try a trick of theirs. Periodically setting a bowl of bakers yeast, mixed with warm water and a bit of sugar, into the greenhouse with the plants and letting it froth. My plants may currently be getting enough from the air gaps and my breathing on them/ talking to them but there have been studies that have found that plants grow better when they have an excess of CO2. Think oxygen bar, only for plants! So I am off to give my babies a natural high and I will let you all know how it works out.
p.s. this also appeals to my thrifty side. I have 3/4 empty jar of yeast in the fridge that is a little past its prime for bread making. Since how long it takes too long to froth doesn't matter, or whether or not it froths as much as it should, I can happily use it for this application and not worry if my bread is going to turn out a hard lump or that I am wasting something! YAY!