In article ,
NT wrote:

If adding more CO2 helped growth, use of gas & paraffin heaters would
presumably be more widespread in greenhouses.

I saw a summary of some research on this a while back. It's very
complicated, as you might expect, but far more plants suffer from
raised levels than benefit from them. As you say, in the UK, light
is the main limit - but there a zillion other factors, and each
species has different requirements.


Regards,
Nick Maclaren.