dont worry the 4x 4ft t5s wiill do the jod these lights in cool blue are good for veg i was using 8 x 5ft 58 watt t5s for the last 2 years with exellent results hear are some picks.keep them about 6 inches from the plants and they will do 8 plants for 4 weeks veg any more and you would need to add some more lights .hope this helps be safe the postman.PS these plants were trained for to go under a scrog so the are lst