Answer: If it is extremely dense, the plants will not grow as well as they would have with a more generous spacing. It is difficult to avoid damaging the plants you want to keep when you thin, but you can certainly harvest and eat the thinnings. You can also harvest the mesclun by shearing it off repeatedly and allowing it to regrow. You may want to use a combination of the two methods. Keep in mind that many of the blends do not tolerate heat, or turn very bitter in the heat, or will bolt and go to seed, so it's probably a good idea to eat and enjoy as much of it as you can before the summer weather hits. For the same reasons, you may want to replant in the fall. Mixing the seed with a bit of sand can help you seed more thinly.
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