Harvest and Handling
Depending on the variety, it often takes 50-70 days from transplanting till harvest. Mature heads should be compact, uniform in color (no yellowing or flowering), and tight. Cut the center head with 3-4 inches of stem. Side shoots will develop if plants are watered and fertilized. These shoots are harvested as bunching heads over several weeks. For a continuous supply of the main crowns, seed and/or transplant every 2 to 3 weeks from early spring until mid-July
Broccoli heads ready for harvest should be compact, tight, and uniform in color.
Depending on the variety, it often takes 90-120 days from planting till harvest. Begin harvesting early sprouts for the fresh market as soon as the lower ones on the stalk are appropriately sized (1-1.5 inches). This will allow the upper sprouts to continue enlarging for later harvest. For uniform sprout size and maturity on the stalk, plants are topped (growing point pinched out) when the lower sprouts are beginning to size (mid-August). Whole stalks can be harvested and marketed using this technique. Plants are very frost tolerant and can be left standing in the field till early December
Brussels sprout stalks.
Depending on the variety, it often takes 80-100 days from planting till harvest. Heads are commonly hand harvested when they are hard. Cut at the base, trim off the outer wrapper leaves, and pack in cardboard boxes or bulk bins. Fields may be harvested three or four times as maturity time may vary.
Cabbage heads ready to harvest.
Depending on the variety, it often takes 70-90 days from planting till harvest. A bright white color is critical at harvest for a premium cauliflower curd. When exposed to sunlight, the curd yellows so heads must be shaded (known as blanching). Cultivars with large, upright leaves (called self-blanching types) do not generally need tying. However, most growers tie up the leaves to protect the curd during the last 7-14 days prior to harvest. This is done by breaking leaves over the curd or tying the leaves together with elastic bands. The use of different colored elastics is used to indicate which heads are ready to harvest next. Heads should be at least 6 inches in diameter, fully developed, compact, and several of the leaves are left on to protect the head.
Greens (Collards, Kale, Mustards)
Depending on the variety, it often takes 50-70 days from planting till harvest. Leaves are commonly hand harvested. Cut off the whole plant at the base or individually remove older leaves which allows the plant to continue to grow. Leaves are washed, tied, and packed in cardboard boxes. Fields may be harvested three or four times as maturity time may vary and quality deteriorates with age.
Depending on the variety, it often takes 40-60 days from planting till harvest. Harvest by hand when the swollen stem is 2-3 inches in diameter. Pull up the plants, wash, cut off the root and tie several plants (with leaves) to form a bunch. Fields are often harvested three or four times as maturity varies.
Postharvest Handling and Storage
The optimal storage conditions for all brassicas are cold (32-35°F) and moist (+95% relative humidity). Length of storage varies greatly. Under good conditions, cabbage can be stored for more than 6 months, broccoli, Brussels sprouts, and cauliflower for 2-4 weeks, kohlrabi for 1-2 weeks, and the greens for 2-3 weeks. The brassicas are quite sensitive to ethylene gas so do not store with fruit. Ethylene causes leaf or curd color changes, leaf abscission, head yellowing, and increases bitterness.
For more detail on storage and handling of the different brassicas, refer to the specific produce fact sheets available through the UC Davis Postharvest Technology website: http://postharvest.ucdavis.edu. These fact sheets are comprehensive guides to maintaining postharvest quality of the specific crop of interest.