Optimal Plant Populations for Crown-cut Broccoli in Highly Productive Eastern Sites

For broccoli to be a competitive crop among Eastern Vegetable growers, it needs to fit well in the rotation and be at least as profitable as alternatives. At the historic yield of 450 boxes per acre, the crop is not a strong competitor. Our crop budgets indicate that a yield of 600 boxes per acre would make a substantial difference in profit, and therefore how likely growers would be to plant broccoli. The smaller crown-cut heads (4.5-5.25 inches) currently favored by the marked is likely to have an optimal plant population higher than the historic standard of 15-20,000 plants per acre. We tested two morphologically different varieties, ‘Diplomat’, which has long branches, and BC1691, which has short branches, at populations of 26,000, 39,000 and 52,000 per acre, using production techniques intended to produce the maximum yield. The optimum both for yield and quality was 39,000 plants per acre, with an average yield of 630 boxes for the ‘Diplomat’ and 800 boxes per acre for BC1691. At the lower population, ‘Diplomat’ developed hollow stem and BC1691became oversized quickly. At the high population, the heads in the second cutting and later were too light, making harvest more expensive, more cuttings were required to get the whole crop, the heads were difficult to find in the field, and some plants produced no head at all.   At the optimal population, the net profit to the grower is predicted to be $2000 to $4000 per acre.  The net profit at higher and lower populations was $300 to $1400 less.