Other way 'round.

0.5 gram dried,
Per watt of HPS light in the flower chamber,
Per month of time (30 days) the plant spends in the flower chamber

This equates to 1 gram per watt per 60 days.

That's the precise measurement for grow skill.

The constant is 0.5.
Say you are running a 7 week strain (49 days) under 2-600HPS.
0.5 x 1200= 600 per 30 days corrected 8/14 by stinky... I'm dense
600/30= x/49
Solve for x to find your target harvest weight.
x=980 and that is how many grams per harvest a good grower should be able to get with that strain and setup. That's about a pound.

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