(Image from: https://hudsonvalleyseed.com/products/parris-island-cos-lettuce?_pos=1&_psq=parris&_ss=e&_v=1.0&variant=31280958734381)
Growing Instructions for Parris Island Cos Lettuce:
Sow indoors beginning 8-10 weeks before last frost, or direct sow beginning about 4 weeks before last frost. Continue sowing until about 2 weeks before first fall frost. Lettuce likes steady (but not excessive) moisture; keep irrigated for best-tasting leaves.
(from Hudson Valley Seed Company website)