Different plants have different light intensity requirements. Again this needs also varies for different growth stages. For instance, the seeding period requires less light intensity but flowering/fruiting requires high Light intensity. However, in general, 1000 to 2000 µmol/m²/s is considered the best light intensity for plants. Or you can go for LED grow lights with a 500 to 1,000-foot-candle range or 15 or more watts per square foot area.