|'Optima' is a butterhead lettuce generally ready to harvest 55 days after sowing. This is one of the darkest-green Boston types currently available. It is a large-framed lettuce with thick, dark green leaves which tolerate heat well. Resistant to bolting and tip burn. Start from seed 4 to 6 weeks before average last frost date. Sow seeds 1/4 inch deep in wide rows and thin to 8 to 12 inches apart. Thinned seedlings can be replanted. Keep soil moist but not soggy. Protect from rabbits and slugs. Extend the harvest season by planting successive crops. Summer heat causes lettuce to bolt. Pick outer leaves as they grow or harvest all at once. Harvesting when weather or day temperature is cooler will result in crisper leaves. Do not harvest lettuces until you are ready to use it.