45 to 60 days — Also known as 'Burpee's Green Ice', the plants develop heavily-savoyed, glossy, dark-green leaves that are exceptionally crisp. Best if grown as a cool season crop, as like many lettuce varieties, it can become bitter in hot weather. However, it is resistant to bolting. Developed as a stabilized cross between 'Grand Rapids' and 'Fordhook,' 'Green Ice' was bred and introduced by W. Atlee Burpee Company
in 1973. It is notable for being the first plant ever patented; its PVP protection expired in 1990. Each packet contains one gram, which is approximately 500 to 600 seeds.