I pinched my first harvest today, and it was the Lettuce Mesclun I received as a gift along with the rest of my order from Botanical Interests.
I planted the whole package of Lettuce Mesclun on February 17 and started pinching individual leaves about 4 inches long today. Anything smaller is left on the ground so they can grow more. Information on the inside of the seed packet suggested cutting off 2 inches above ground level if I want to harvest whole heads. Whatever is left will grow more from the center.
Seeds can be sown from as early as 6 weeks before last frost of winter till 2 weeks before first frost in fall. In USDA zone 8 or warmer (which is where I am) I can even sow seeds in fall for a winter harvest. Lettuce can survive in temperatures as low as 20F, though 70F is ideal for seed germination. I have mine planted on the north side of our house, and next to peas, for adequate shade that will protect the leaves from harsh sunlight. Summers are brutal here.
For now, these early harvests are so tender and sweet. I will be planting some more of these before it gets too hot.