You'll want a minimum 20 or so umol/s per sq ft. reputable lights have reputable spec sheets. divie umol/s produced by sq footage of coverage and it'll tell you if you are hitting ~20-22 DLI, which is about as low as you can go. If underpowered like that, better to go wtih autoflowers, since you can run your light longer and sqeeze out a proportionally larger DLI.