I have had mixed results in trying to grow a fall crop of lettuce. It grew well, but then mysteriously started to disappear.
When my Black Simpson lettuce went to seed, I used some for a fall planting. New lettuce came up and was doing well until it got too cold. I moved the pots indoors to my makeshift family room greenhouse, and the lettuce thrived. Future salad seemed possible.
Then, I noticed a thinning of lettuce in one of the pots. I thought some of the lettuce might have dried out, but the rest was doing well. A week later, half the lettuce in the pot had disappeared. Lettuce continued to disappear until one pot was bare; then the other pot of lettuce also started to disappear. I have discovered that my dog Bosco is helping himself to some daily greens