here in Austraila i can grow lettuce all year round and it can tasted sweeter in winter too but if you think it may be a little too cool in your area try using a coldframe and there should be little to no problem.

Here is a link that might be useful: organic gardeing

In 5b you'd most definitely need a cold frame or a tunnel.

In 5b the best way to get early lettuce is to start seeds indoors in late winter and set them out under cloches or in a frame in March. A few varieties like Winter Density will overwinter, but repeated freezes make the leaves a funny texture that is not wonderful. Deer, rabbits, etc think winter lettuce is for them.

I definitely agree with the idea of using low tunnels or cold frames. We have both and I was considering using the tunnel for sure (if not both). We use the cold frame in early spring/late winter to harden off transplants and it can get rather crowded, but I was hoping to get a big enough lettuce crop to just tide over till the early planted lettuce gets started to get the season of fresh salads going a bit earlier.

Plant you lettuce in early March, it will be ready to harvest in early April.

Anything you plant now will be ready in 21-30 days. Last year I transplanted lettuce in November, harvest after Christmas. Direct seeded lettuce on December 30th, harvested in March. This was inside a high tunnel.

Jay

I'm in 5b and I plant in September for overwintering lettuce -- some of it under fleece, and some outside, it all does fine. I've bought lots of winter lettuces -- winter density, rouge d'hiver, etc -- but then the volunteer red sails and black seeded simpson, out in the open under feet of snow, do really well just to show me I didn't need to go though all that fuss. And yes, it's great in March and April (spinach too!)

Jay - your lettuce grows a lot faster than mine! Mine grows really slow once it's cooler and shorter days, which is why I plant in Sept for spring harvest.

i agree with elisa_Z5 spinach and swisschard is a good alternative to lettuce in the winter as i know that the swisschard can be used in salads with very little to no cooking. and it tasted great toooo Mmmmmmmm