Lettuce is another really easy seed to save as the plants are self pollinators and can have as little as 2' of isolation. Plant your lettuce seed and let them bolt. at gthis point rogue out (get rid of) any plants showing traits you don't like-fast to bolt, slow growing heads, bad color etc., and keep only those you want. You should be left with at least 6 heads for genetic diversity. I know I just said they are self pollination but there is always a little bit of genetic drift.
When the plants bolt they are a few weeks from making seed heads. watch for flowering and than watch for the seeds to develop. They are ready to harvest when the fuzz turns white and fluffy and the seeds are brown (or black or white-what ever the color was that you started with). Collect the seeds in a paper bag (lunch bag size is large enough) with the fuzz. lkater clean the fluff off and store. I store these seeds in the freezer as I have had bugs get into them in the past and they don't mind it being cold.
What are you growing this year? I've got 12 varieties going, mixed leaf and head types. First batch went in two weeks ago, and is just starting to germinate. Hopefully, I'll get the second batch in this week (if it stops raining), and the last batch two weeks after that.
I am figuring that because lettuce is a self pollinator, like beans, there really are no true hybrids out there and that the seeds should come back true. I may be wrong but hey, I have the seed, the time and the room to try it.
One other point about lettuce that makes it easy to save seed. Different varieites bloom at different times, and, in some cases, the flowers remain fertile for as little as an hour. Thus, if variety A blooms in, say, 45 days, and variety B blooms in 46 days, there is little liklihood of them crossing.
I have friends who grow lettuces in rows as little as 3" apart, and they say they've never had crosses. I think 3" is crowding the plants (would be okay for a cut & come again patch, but not for seed saving), but find the concept of purity at that distance credible.
Certainly. A foot is plenty, really, for lettuces.
You know, you almost have to work at it to get lettuces to cross at all. They are so self-sufficient in terms of self-pollinating, when they blossom, period of fertility (which is never very long), etc. etc. The true lone-wolfs of the garden.