# Greenhouse Growing: cloudy days



## leafminer (Feb 18, 2010)

Does anyone know how many lumens of ambient light the plants receive on a cloudy day? From what I can find after 30 minutes of research (not a lot) it is between 1500 - 2500 L/ft.sq. but if anyone knows better then please correct this.

Now this isn't enough to flower properly but it ocurred to me that I have a spare unused lamp, the monstrous MV lamp. It's unused because it is too inefficient producing only 10K lumens at 450W power. 

However, the GH is also too COLD at this time of year slowing growth down - on cloudy days there's little to no GH effect. So I thought, oho, if I rig up my MV lamp it will warm the place up on cloudy days and also provide me with an extra 2K lumens/ft.sq, together with the ambient - say 2K - that's much better for flowering than before.

What do you think?

PS, mods, could there be a sub-forum for greenhouse growers? I never know where to post, and it's very different from indoor or outdoor.


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