.You need 180W led to cover 4 plants. Leds have received much bad press especially concerning their effectiveness in the flowering stage but the fact is, they are the way forward and can outperform all other lighting. Poor results reflect current ignorance of required specs. Most of the lights on the market,.for instance, have way too low a ratio of red light (essential for flowering) to blue; 3W, 5W etc. bulbs are being promoted when single watts are more efficient; the interdependency .of different wavelengths is ignored; and so on. Do your own research into 'light and plant growth' .before buying. I vegged 4 widows under led then moved 2 under sodium for flowering and added a 90W red led (cheap from China) to the 2 remaining. The buds on the led plants are, by far, superior in terms of size, profusion and quality. I'll post yields after harvest in a couple of weeks. Go for led, the advantages are massive.....and good luck!