lighting question

[helpmegrowbro]

hi I have a room that is 2.1 metres wide and same length a 400 watt metal Halulite light and a 400 watt hps light will be big enuf to grow a plant?

[Luke Skywalker]

Hi there helpmegrowbro.

 

I would suggest to fully illuminate such an area you would be looking at 3 or 4 600w HPS lights. A single 400w is okay for anything between 0.5 to 1m2 of canopy. 600's cover around 1 to 1.5 m2 of horizontal space. Look at building an enclosure or using a wardrobe sized area for your average 400w room. I would suggest having a look through a few grow diaries and other threads with active grows to see what kind of space you're looking at. To start out a 400w kit is a good way to go, but a 600w lamp will cover and produce significantly more. Remember that the growing area wants to be enclosed, light tight and well ventilated.

 

Good luck!

[jimbojones5678]

Yeah Luke's on the money...I'd be throwing 4 x 600w in an area that size

 

400w = 1m x 1m

600w = 1.2m x 1.2m

1000w = 1.5 x 1.5m

 

Jimbo

[BaronS]

gonna throw an idea in here for people to consider. You see, the idea of 'watts per square (meter or foot)' doesn't seem right to me and we should be looking more to 'lumens per square'.

 

Not only does the 'lumens per watt' vary between lamp types but also by manufacturer. Also, the 'useful lumens', which relate to temperature (deg K), need to be considered.

 

I agree with both Luke and Jimbo's assesment of MH/HPS wattage, based on reading various recommendations which make me suggest 'minimally 20 but better 40-60 Watts per square foot'. I just don't like the assumption that Watts is a useful figure to work with.

[Luke Skywalker]

Watts per square foot is only a guide, obviously. Ultimately lumens aren't a very good measure either. The best one is PAR watts but not many manufacturers will give you these figures. The difference in luminosity from one brand to another does not necessarily relate to the increase in plant usable energy.