SUMMER HARVEST. Copenhagen Market cabbage seeds are a Danish heirloom introduced by H. Hartman & Co. in 1909. This early variety forms round, solid heads 15-20cm (6-8″) in diameter, making it the largest early round-head cabbage for summer harvest. This summer harvest variety has good keeping ability, excellent uniformity, and rich flavour. This variety is outstanding for coleslaw. It’s a popular market variety that has the added benefit of shipping very well. Protect your cabbage row from the caterpillar of the cabbage moth by draping lightweight row cover over the plants.