Too much wattage?

Watch the plants. they'll scream, "Too much light mf'ers!" ... in not so many words.. none at all. The distance that develops between growth nodes is an easy visible thing you can use to adjust your light's power. Too tight = needs less. Too stretchy = needs more. Find that goldielocks zone. Once you find it, a klux measurment is all you need to repat it in future. hours of operation and umol/s of PAR is what matters. This amounts to DLI (daily light integral). You baby them only as long as they shy away from intense light, otherwise ramp it up the moment they can handle it. 18h with highly efficient lights will only need 22-25w/sq ft and 150% of that over 12 hours. The amount of umol/s of PAR is 1:1 inversely proportional to hours of light as you can see. Once mature, you want to give the same DLI in vege as you will in bloom. Eliminates a lot of the guesswork if you understand DLI. The wiki has decent info on it. Less efficient lighting will need 10-20% more than the above. Based on the blurple spectrum, i'd wager you need to go 20-25% more and then observe and react as explained above. With tiny plants, you can give a lot less watts if you can cover a very small area while they aren't too tall. This will save you money. If you don'thave a proper dimmer for the LED, then you kinda justget stuck giving full power and you adjust intensity on the plans with hanging distance... It's better that hanging distance is guided by coverage needs, but you do what you have to do. it'snot a big deal wehn speaking of a 300w context, so no worries.