A large heirloom cabbage from 1889 with deep red heads that have good flavor and color. (90 days)
Start seeds 4-6 weeks prior to desired transplanting date. Seedlings need bright artificial light or full sun; a cold frame is ideal. Seed should be covered no deeper than 1/4 inch. Grow Mammoth Red Rock in relatively cool conditions — no more than about 75 degrees Fahrenheit during the day, as cool as 45 degrees at night.
When young plants have developed 2 to 4 true leaves they are ready to transplant in the garden. Set plants out 4 weeks prior to last frost date in the spring or 4-6 weeks before first frost when fall-planting. Space about 24-inches apart. Plants need good rich soil and abundant moisture to produce solid, crisp heads. Some varieties will produce secondary heads when the main head is cut cleanly from the stem just above ground.