Probably not much. I planted some in just a few inches of rocky, glass-laden soil last year on the neglected side of my yard, and it did fine until it got hot. If you want to be safe, maybe 4-6 inches of depth, especially if you're using some compost in the planter. I'm thinking you might want to hang a grow light in the windowsill (I use the cheap florescent tube lights), but can't say for sure, not having seen the window.

Happy gardening :-)

In my new cold frames this year, I tried growing lettuce in one of those under-bed storage boxes, the opaque kind (without the cover, obviously). It has about 4 to five inches of soil in it, and the lettuces are doing well. I do cut mine at the baby stage.

I work with a woman who sells lettuces at the market, and she starts her trays in the greenhouse, and sometimes they kind of get away from us (i.e. we don't always get the seedlings planted out!). The lettuce did so well in those flats that we decided to sell mixes and grow those in the greenhouse, in regular flats.

Can't help you about the amount of sun, but I would give it a try. Days are getting longer...

:)
Dee

IME, lettuce doesn't require a lot of light. When I was a kid, dad sowed lettuce seed in our tobacco beds because it grew faster than the tobacco. We always covered the beds with a cotton canvas so the plants were always grown "in the shade" until it was time to harden them off for transplant.

I grew mine (Black Seeded Simpson) under a bedsheet last year. It helps keep it from bolting and also from getting tougher. Can't say if it was an aberration or not, but one stalk survived until January - that was after several very hard freezes and at least one snowfall.

Mike

Lisa, I have grown potted lettuces for years in 14-inch or so plastic bulb pans in potting soil. The soil depth is about 6 inches. The pots are easy to handle. I put them out on the patio, which is partly sunny and keep them moist, uncovered. I always have a lot of nice mesclan and mixed lettuces in early summer for stir-fry and salads. When the plants are up a few inches, I transfer the pans to a sunnier spot and thin them out for quite a long time before they bolt, at which time they join stuff in the compost bin. They never are planted in my vegetable garden.
Sunny

If you put them in a pan doesn't it need to also have drainage? I have several never used foil roaster pans that i am thinking would work for a small amount but would i need to use 2, one with holes in the bottom inside one without?

Amprice, there's a type of pot called a "bulb pan." It's for forcing tulips, etc., I guess. It has a hole in the bottom. I don't ever use the foil pans because I think they are not as easy to move around as the rigid plastic bulb pot.
Sunny

Under bed storage bins have worked for me in the past. Inside you woudl need drainage as long as you dont overwater them. If they are outside then you would want a few holes becasue you cant control how much it rains.