greenhouse lighting

[natorgway]

I would like to know what the minimum light requirement I would need to grow some plants during the winter. I am going to try to grow mainly salad crops, lettuce, tomatoes and radishes etc. The area is approx 7ftx7ft and 6ft high, covered in polytunnel anti condensation sheet, and heated by gas heater. I would like to know the difference between the large array of different tubes and bulbs. ie. I have a 500watt halogen floodlight, could that be used and would it supply the correct type of light, although that would be expensive to run it would only be used to extend the daylight/growing hours. Is 12 hours liight sufficent for maintaining healthy plant growth.

The second alternative I am looking at which would be cheaper to run and safer is the use of growlight tubes. Obviously they are a greatly reduced wattage but what length of tube and wattage would be needed to maintain growth for a) just extending the daylight hours timing the lights to come on at 6am until full daylight ( maybe 9am) and on again at 4pm until about 8pm, with some added light in the daytime on dull days., and b) for lights on all day 6am until 8pm in dark rooms.

What are the differences between the types of growlight tubes ..........strip lights, spotlights, halospot, halolux, halogen, halopin, high intensity discharge light bulbs (H.I.D.), full spectrum light bulbs, micrographic light bulbs, sunbed tubes, aquaria light bulbs and plantgrowth light bulbs. warm light, daylight, cool light etc etc.

I am sorry to ask so many questions but there are many different kids of light unit on the market and the varieties are somewhat confusing.

Regards