Sprouting broccoli is a traditional English crop for fresh market and home gardeners. Sprouting broccoli produces many small shoots, rather than a single head. Many varieties require a cold treatment, or vernalization, before making sprouts. In England, sprouting broccoli is planted in late summer, and plants grow very slowly during the fall and winter. The next spring, they produce prolific amounts of small purple or white florets on long bright green leafy stems. The shoots are harvested from March to May, when other fresh local vegetables are in short supply and high demand. Unlike broccoli rabe or rapini, the shoots are mild-flavored, even sweeter than summer broccoli.
From 2007-2010, we grew several varieties of winter sprouting broccoli in unheated high tunnels in Durham, NH. Inside the tunnels, plants were covered with an additional layer of heavyweight (1.25 oz per square yard) spunbonded polyester rowcover during the coldest part of the winter (late Nov-early Mar). After establishment, the plants were not watered, fertilized, or otherwise managed during the winter. Winter temperatures were below 0F for several days; in 2009 the crop survived a low temperature of -18F. Access the full report for more details.