How many plants can I put under a 4 ft shop light with 2, 40 watt bulbs? I am getting mixed advicce. Help
best thing 2 do is work in lumens... 100 watts a plants dont mean nothing as diffrent lights and light heights effect lumen output!! best thing to do is work out how many lumens your light puts out for example. my 600 watt super hps puts out 95,000 lumens at the lamp for each foot the light has to trevel lumens diminish by half so 12 inches under my light there is 47,500 lumens. Then if there is 10 plants then we divide the 47,500 by 10 and the amount of lumens each plant is geting is 4750 lumens each. There is no maximum amount of lumens ( the sun emits 10,000 lumens every square foot of the planet) so 10,000 lumens each plant is what we are aiming for but its unrealistic with indoor lights so the lowest id say for healthy growth is 2,500 lumens each minium and 5,000 max unless you can achieve more.. Hope this helps
P.s beacuse of the low power and low wattage of the long flourescents id say you have enough power for the 2 week seedling stage, I would then upgrade to either High powerd CFLs or HID lighting for best reults..
On my set up I'm using a 4' 2 bulb shop light with T8 6500K bulbs. I have 3 plants and 4 ea 23w 2700K CFL's as well. I plan on adding more but my ladies seem to be ok so far.