I use two cool 40 watt bulbs, and that's it.
Of course, this is for seedlings....eventually they go outdoors.

Josh

On a standard seed tray I would try to use 4 total bulbs or two double shop lights with cool white bulbs. more is better when it comes to light!

Agreed with stquack, on a standard width seed tray (10" x 20"), you'll want two sets of shop lights, side by side, for a total of four bulbs. It'll give you that bigger, more noticeable head start you're looking for. It'll also keep the outlying plants from stretching out too much.

My shelves are 18in X 4ft.
I use 3 dual bulb shop lights.
I think using as many different bulbs that are between 5000K and 6000K are better than all bulbs being 1 color.
I think I get better growth from a mix than with only 1 temp. bulb.

twin tube shop lights are great, i have 4 of them running so far with a 5th on standby.

A little reflective material surrounding the grow area such as aluminum foil helps too.

And those lights are cheap on wattage and offer ambient lighting if they are in a living area, u wont need to turn regular lighting on in the evening to save on electricity.

They work great

Happy growing
Jim

{{gwi:1150803}}
I use 4 standard trays under 5 shop lights.(400 watts)

I have banks of three 2 shop lights. I remove the tubes and use spray adhesive to stick aluminum foil onto the reflectors to give them more "punch." I use a combination of grow lights (GE) and the ones that are natural spectrum because they put out more lumens. Those are 6 week old Bhut Jolokias peeking our from underneath. I usually drape a half of a mylar space blanket over the top of the lights to help keep more heat in and reflect stray light back in toward the plants. This technique has served me very well over the years.