Collards tolerate cold weather so they can be started extra early. You can start collard seeds indoors 3/15-8/1 at 72-85° (can use a heating mat). Days to germination: 5-8. Transplant outside , 12” apart. Or, sow collard seeds directly outside anytime 4/15 – 8/15. Sow 3-4 seeds together in a group ½” deep, spaced 12” between groups. Keep seeds evenly moist until germination. Thin to the strongest plant in each group. Protect collard plants from deer, groundhogs, and rabbits which will devour them. Collard plants may be eaten by several different species of caterpillars. If they cause damage, hand remove caterpillars or spray organic BT.
Harvest individual leaves off of mature plants once they are 2 months old. Don’t remove more than 1/3 of the leaves at a time.
Collards are somewhat difficult to save seed from. Collard plants must overwinter in order to bloom and produce seed. Sometimes they will survive the winter with protection. Collard is in the Brassica family so it is insect pollinated and cross-pollinated. Collards will cross with any Brassica oleracea that are flowering at the same time (broccoli, kale, cabbage, brussels sprouts, kohlrabi, cauliflower). Isolation distance: ½ mile. Collards can suffer from inbreeding depression if you don’t save seeds from enough plants. Minimum population size: 10-50 plants. To harvest seed, allow plants to flower and collect seed from mature pods.