A tall growing, non heading member of the cabbage family, tree collards were introduced to California, probably during the latter half of the eighteenth century. They are nutritious and a 100 square foot bed can provide four times more protein and eight times more calcium than the milk produced from a fodder crop grown in the same area. In addition, tree collards contain no oxalic acid; therefore, they may be eaten raw without iron being tied up. Perennial Purple Tree Collard leaves are rich in calcium (226 mg per cup, cooked), vitamins B1, B2, B9, and C (which may be leached by cooking, however), as well as beta-carotene (pro-vitamin A). They are high in soluble fiber and contain multiple nutrients with potent anti-cancer properties: diindolylmethane, sulforaphane and selenium. They gained national fame when Eric Toiensmeier cited them as one of the only decent tasting perennial brassicas he had ever tried in his book Perennial Vegetables. Tree Collards can be used raw or cooked in recipes that call for kale, collards or cabbage, and are especially good in soup. They take longer to cook than spinach but can be substituted in some recipes. Finely shredded raw leaves may be added to salads, sandwiches and tacos. Steamed: saute onion and garlic in large pot. Add shredded tree collards leaves and a small amount of water. Cover pot, stir after about five minutes and continue steaming until tender. Tree Collards can thrive for four to five years (and possibly 20 years), it is probably better to rotate them after three years, since they remove so much calcium from the soil. You may wish to consider taking cuttings, plant a new bed, and get it established, before removing the old bed. Tree Collards will grow well in most temperate climates, although there may be approximately 75% die back if temperature drops to 20 degrees F and stays there for any length of time. In this kind of environment, take cuttings one month before the first hard frost ( or use prunings), flat them and keep them in a greenhouse to overwinter; one month after the last hard frost in the spring, transplant the cuttings. Tree Collards do not normally flower or make seed, and when they do, the seed does not breed true. Instead propagation is by cuttings. During the first year of growth, tree collards may grow 3 to 4 feet tall before winter comes. The following year, they may reach 6 to 9 feet tall. Tree Collards should be pruned 2 to 3 weeks before the hottest summer heat about the end of July. This will give the plant enough time to regrow for the winter harvest to begin in November. The goal is for the plant to produce fewer medium to large leaves rather than a lot of smaller leaves. For ease of harvesting prune the plants just above a node, to 2 feet high the first year, 2.5 feet high the second year, and 3 feet high the third year, this gives the best yields over time. Prune out thin, weak, woody, bent or twisted stems. Leave the 3 to 4 healthiest and strongest stems that are "evenly radial" leaders (more or less evenly spaced around the stem). Remove the others. Leave any leaves on the remaining plant stems, but remove any small branches. Be sure the pruned stems are tied securely to their stakes with string in a figure-eight loop. Loosen the soil 3 to 4 inches deep between the tree collards and around the edges of the bed, to aerate the soil and let water in more easily. Water well (approximately 6 min./100 sq. ft.). Cover the bed immediately with shade netting, to protect the pruned plants from excess heat, if necessary, until the new leaf sprouts are about 3 inches long. Water them at midday to help them regrow and keep them cool until the mini-climate is re-established. One to two months later, prune off any small branches growing below 2 to 2.5 feet. Prune off smaller stems above this level if a lot of small stems shoot out after pruning, but be sure to leave 3 to 4 strong, evenly radial stems.
We have enjoyed our plant leaves year round but they are best in the winter months. You may eat all of the leaves or remove the stem its up to your taste. I leave stems in when cooking.