OK, Got the light... Now what

18 years ago

Howdy all,

Bought an ebay special 400W 110V HPS grow light with MH conversion bulb. ($120 shipped) I have a few basil plants and tomato seedlings that I started under flourescent bulbs. I fired up the MH conversion bulb (the 'growth' bulb yes?). Holy crap! Is it ever bright! Need to add some foil to further direct the light. It has a little hum to the ballast. I assume this is normal. How high above the plants should I go? About what square footage can I expect to illuminate effectively? Any thought on what photoperiod would be reasonable?

The basil is regular old basil and purple basil. The tomato is Ukrainian Cossak (an early, small determinant tomato). How do I know when to switch to HPS? Thanks for the help all! Off to IKEA this weekend to buy more GORM shelved (an imminently modular shelf that is cheap!)

Doc van Phil

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Comment (1)

watergal
18 years ago
I would start with the light several feet away from the seedlings and gradually lower it, maybe 6 inches every few days, so you don't sunburn the leaves.

Yes, MH is the growth bulb and a slight ballast hum is to be expected. General guideline is really good light for a 4x4 foot area, supplemental light for a 6x6 or even 8x8 foot area. Obviously the light is much brighter in the middle.

I would try 16 hours on, 8 hours off per day. Buy a timer - it will save you much aggravation for only a few $$$.

Can't help with the switch to HPS as I've never used one. I believe they are supposed to encourage bud formation, so I would guess you switch when the plants are the appropriate size for blooming.
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