Depends I on what those lamps really are. I am not familiar with a 48" 20 watt fluorescent lamp. It should have been 32 to 40 watts and 48" long and putting out 2500 to 3000 lumens each. If so, you would probably do okay with the 7500 lumens per 3 square feet or 2500 lumens per square foot. You should probably be fine like that. If the lamps are not really 48", since that will only just barely fit in your closet, and are really 24" then they put out probably half of what we said above and you will be hurting for light but I think you would still get some harvest.

Can you get any daylight to them to supplement? Any more fluorescenet bulbs available? HID's are not essential, just as much light as you can get.

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