I know it’s a “classic” column, but I can still complain, right?
The reason I’ve always heard for why you should talk to your plants wasn’t even mentioned in the column. It seems pretty obvious to me. Carbon Dioxide! Plants breathe it, we exhale it. Sitting in front of a plant talking to it should create an are of slightly increased CO2 (4-5% higher in exhaled breath then usual), which should have a measurable effect on growth. Maybe not to the tune of the 89% taller, but still worth a mention.
I always thought the increased CO2 might be beneficial as well. Mostly I just figure people who talk to their plants probably care about them (and for them) more than say me, who mostly remembers to water her plants…sometimes.
Even if you filled a room with exhaled breaths, and increased the CO2 in the plants environment by 5%, it wouldn’t make a noticeable difference in growth. According to this page, a 5% increase in CO2 would result in about 5% extra growth.
My plant propagation professor always told the story, while explaining plant growth chambers, about how warm, moist carbon dioxide was the reason some thought their plants grew better if on talked to them.
It’s only a 5% increase if you fill the plants environment with enriched air. Breathing directly on a plant will not increase the CO2 levels around the plant significantly.
I don’t think talking to your plant will increase the available CO2 by even 1%.
And even if it did, you’d have to talk 24/7 to keep that increased level up. Talking to your plants for an hour and increasing the C0[sub]2[/sub] level 5% for 1/24 of a day isn’t going to translate into 5% total. Any improvement will be lost in the data noise level.