how many light/watts per plant at 1m3

You should keep in mind, the less light you have, the taller your plant is going to be. Also, if you only have 3 feet in height make sure you put them into bloom early enough or you will quickly run out of space - especially if you're just using CFL's. A height of 3 feet isn't really enough for an HID (maybe a 250 watt) but I think if you were to use a nice T5 fluorescent that might just do the trick for you - IF you bloom early enough.

well i think i might be able to extend the space from a veggitated bush almost in a 1m3 box to a 2m3 box when in bloom

maybe even 3m3

Don't worry about about making your space wider, just taller. A common beginner mistake is trying to cover too big of an area for the lights they have. Use this as a guide: 400 watts = 4x4 feet max; 600w = 5x5; 1000w = 6x6 - and that's pushing it. For optimum lighting it should really be 400 = 3x3; 600 = 4x4; 1000 = 5x5 - you get the idea ... too big of a space means lost lighting. If you keep your space to the right size you can 'contain' the most light to maximize it for plant growth. (Make sure you have excellent ventilation.)

Since you're only growing one plant you'll need to grow to a decent height to get a decent yield, which obviously means, decent height in your space. Is there a reason you're only growing one? Alternatively you could grow a bunch of smaller plants and reap (at least) the same yield. The sea of green approach offers a quicker turn around time (time to get to harvest) and (in my own opinion) it is easier to maintain healthy plants. I'll attach a couple of pics of my current grow to give you an idea. These were taken a week ago, something like that. Just trying to provide you with some useful information before you get started.

Note about the pics: These were taken on the day I put them into bloom so the males haven't been removed yet. When they are, (and as the plants get bigger) the spacing will work out very nicely, i.e., a 'sea of green' with just females. I know because this isn't the first time I have done this - the first time was in 1974. Notice the compact growth - tight node development, bushy plants ... this is the result of proper lighting in the right sized space, as opposed to those tall stringy plants you see all over this site. (Strain makes a difference too of course, for example, sativas are stringy by nature, but with good lighting and so forth you can at least keep that to a natural minimum rather than growing some skyscraper with 6 leaves. )

ok thanks for the info ive got the space so i'll grow with lights on the side aswell with 2000 watts which is 10X10 aint it

Originally Posted by Carribean Blue

ok thanks for the info ive got the space so i'll grow with lights on the side aswell with 2000 watts which is 10X10 aint it

Unfortunately, no. A space 5x10 would be possible however. Think of it this way ... hope I can explain this ... from the center of each light you are covering an area 2-1/2 feet outwards. (For our purposes we think of it as a square.) This gives a total area of 5x5. When you put the 2 lights side by side (5 feet apart because each extends 2-1/2 feet from the center) that gives a total of 10 feet lengthwise (in the direction from bulb to bulb), but the area from side to side hasn't changed any ... although there are 2 lights, both are still only giving proper lighting for 2-1/2 feet each way width-wise. You'll have to tell me if that makes sense to you. If not maybe I'll make a diagram.

Just a thought ... I am thinking of 2, 1000 watt lights in that explanation, but now that I think about it, you didn't actually say what lights you were using ... did you? That should help anyway, if you can understand it. I found that one hard to explain for some reason.

its ok i understand it thanks

i'v got the space so i try to grow the biggest