Once lettuce has developed a firm head, is he ready to cut?

Once lettuce has developed a firm head, is he ready to cut?.

For early outdoor varieties, whose finished heads usually only remain harvestable for a few days, it is recommended, to start harvesting earlier, in order to extend the harvest time and avoid losses due to bolting. outdoor lettuce, which is not ready for cutting until the end of September, should be built over with cold frames or foil. This makes head formation faster and safer. Instead of cold frames, you can also use foil-covered wooden frames or the foil tents used in the spring.