Correct temperatures seem to be as important as strong light for indoor tomato growing. After seedlings germinate, it's generally recommended to grow the plants on at no warmer than 60-65 degrees. The minimum lighting you need is a shoplight or other fixture with two four-foot fluorescent tubes, and preferably more light intensity than that.

If the seedlings are so weak-stemmed that they've fallen over, I suggest starting over again with better growing conditions. When are you expecting to set out plants?

The problem with the regular white bulb is that they produce a wide spectrum of light; most of which is useless for plants. So, even 18 hours of light is insufficient. How about using grow lights with specialized spectrum? If your grow area is big enough, you can use HPS and MH bulbs in combination. HPS bulbs can provide red spectrum of light during the plantâÂÂs vegetative phase and the blue spectrum of MH bulbs can be used in flowering stage. Of course, using these light results in more heat generation. For a smaller grow area, LEDs lights can provide even more specific spectrum and that with much lesser amount of heat. Yes, the initial cost is high; but the benefits will roll-up in successive cycles.

Your plants are not getting enough light. White lights are useless for plants. They give off no light a plant can use. Use T8 daylight bulbs They give a wide spectrum of light. You can use specialized bulbs but the plants do not grow any better under them and they are more expensive.

It is important that your fixture have reflectors so the light is trained downward instead of all over the room. The distance from the lights to the plants is important too. The lights should be no more than an inch away from the plants but not close enough that they touch the bulbs