It's almost Dec 21: A question about light ?
I'm trying to grow tomatoes in the FL winter. I'm curious about light needs for tomato plants. I have read that they need 14hr min of light. This time of year down here, that's impossible. Does strong direct sunlight on a mature tom plant, compensate for lack of hours they get light?
hardland,
How many hours of light a tomato plant needs depends on the intensity of the light. Four hours of bright sunlight (9,000 Foot Candles - a very sunny day in summer) is enough. If the light is only as bright as a 400-watt MH lamp, you will need about 10 hours.
(Tech stuff - the amount of light needed is based on research showing the Daily Light Integral - the amount of usable (PAR) light plants get x the number of hours per day they receive it.)
Mike
How many hours of light a tomato plant needs depends on the intensity of the light. Four hours of bright sunlight (9,000 Foot Candles - a very sunny day in summer) is enough. If the light is only as bright as a 400-watt MH lamp, you will need about 10 hours.
(Tech stuff - the amount of light needed is based on research showing the Daily Light Integral - the amount of usable (PAR) light plants get x the number of hours per day they receive it.)
Mike
hardland,
If you have the bulbs about 3" from the plants, 16 hours would be better. Of course, it they are closer or you have the area lined with Mylar, 14 hours would probably suffice.
Tech stuff - those bulbs are suppose to deliver about 1550 lumens per bulb. At three inches, you should get about 24,000 lux, more with a great reflector. that translates into about 2300 foot candles (again, more depending on the reflector). To calculate the amount of PAR light (the spectrum plants use) you multiply by .000524. That provides about 1.2 moles of light per hour. Seedlings need about 18 moles per day (22 is optimal). Sixteen hours per day would give you a little over 19 moles per day. Fourteen hours will provide about 17 moles/day.
Mike
If you have the bulbs about 3" from the plants, 16 hours would be better. Of course, it they are closer or you have the area lined with Mylar, 14 hours would probably suffice.
Tech stuff - those bulbs are suppose to deliver about 1550 lumens per bulb. At three inches, you should get about 24,000 lux, more with a great reflector. that translates into about 2300 foot candles (again, more depending on the reflector). To calculate the amount of PAR light (the spectrum plants use) you multiply by .000524. That provides about 1.2 moles of light per hour. Seedlings need about 18 moles per day (22 is optimal). Sixteen hours per day would give you a little over 19 moles per day. Fourteen hours will provide about 17 moles/day.
Mike