Answer: The 60 day measure indicates how long it takes for the plant to reach its maximum size for those who plan only to harvest once, but you can begin to harvest leaf lettuce as soon as it is big enough to cut, so yours sounds ready!
If you plan to reharvest, simply trim the largest leaves leaving the plant to continue growing. You may be able to harvest several times, assuming the plants recieve adequate moisture and nutrients. After about 60 days, however, the plant will probably try to set seed. When that happens, the leaves may taste bitter. Some varieties also taste bitter when the weather warms up, so the sooner you begin harvesting the longer you will be able to enjoy your lettuce.
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