Answer: In my experience, lettuce is better as a cool season crop because it turns bitter and bolts or goes to seed once the weather turns hot for the summer. (You can replant later for a fall harvest, though.) In summer we have enjoyed tender new leaves of Swiss chard as a fresh green on sandwiches and the like instead of lettuce. If you really want to try summer lettuce, "Oak Leaf" grown in partial shade might be something to try, but unfortunately I think you will disappointed. When you look at what is available, select varieties described as "bolt resistant" or "heat tolerant" to experiment and see what works best for you.
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