We’ve just finished up the second year of an experiment evaluating several different varieties of brussels sprouts (9 in 2013, 8 in 2014) at the NH Agricultural Experiment Station’s Woodman Farm in Durham, NH. The full report, complete with color photos of all the varieties, is linked HERE. Below, we share the take-home messages.
Variety results, in a nutshell. Of the five cultivars grown in both years, Nautic, Diablo and Jade Cross E yielded well (over 8 oz per stalk). While tall and vigorous, Doric was extremely late to mature, and most sprouts did not reach marketable size. Catskill was also very late, showed considerable variability in growth habit, and yielded poorly in both years.
For those cultivars evaluated in only one year, Gustus, Early Marvel and Octia were promising, with high yields on quality stalks. Nelson and Churchill had high yields but both showed excessive lateral branching and a tendency for bottom sprouts to become oversized. Falstaff and Roodnerf had poor yields, and Falstaff was highly variable with a number of off-type plants.
Topping study. We also studied the effects of topping brussels sprout plants (removing the growing point) during the growing season. Removing the top of the Brussels sprout plant at the right time has been shown to increase the size of the sprouts at the top of the stalk, improving marketable yields. What we showed is that topping can increase yields AND can also make stalks appear fuller and more attractive, for some varieties. You can see photos comparing topped with untapped sprouts in the full report. However, topping too far in advance of harvest can reduce yields and marketability by causing plants to spend energy growing new stalks.
Conclusions about topping. In the past, we have recommended that the timing of topping should be based on the physiological development of the plant, for example, when the largest sprouts are 0.5-1” diameter, rather than on a specific date. Our current thinking is that topping between 30-60 days before harvest, especially once lower sprouts have begun to reach marketable size, will result in the maximum benefit to marketable yields and appearance of Brussels sprouts. If you do not plan to harvest sprouts for at least 60 days, plants should be allowed to continue to grow.
Check out the full report and photos HERE, and please get in touch if you have any questions.