The response of broccoli (Brassica oleracea L., ‘Arcadia’) yield to application rates of mussel sediment (MS) from post-harvest washing as source of nitrogen (N) was evaluated in a 2 yr (2011–2012) study in Bouctouche, NB, Canada. Treatments in 2011 included a control (no amendment or fertilizer), three rates of MS (28 000, 42 000, and 56 000 L·ha⁻¹ equivalent to 14.7, 22.0, and 29.4 kg N·ha⁻¹) and an inorganic N fertilizer (135 kg N·ha⁻¹). In 2012, all plots were split, with just half of each plot receiving a repeat treatment application. Fertilizer and MS increased total fresh yields by 115% and 29%, respectively, compared with the control, with no significant differences between MS application rates. Total dry matter yield followed the same order as total fresh yield, but only at P < 0.10 in either years. Marketable yield was not affected by treatments in 2011 or by their residual effect in 2012, while it was greater in fertilizer compared with other treatments after 2 yr repeated application. The greatest head compactness and the lowest yellow-eye were measured in fertilizer treatment in both years, while no differences among MS treatments and the control were observed. The effect of treatments on total dry biomass and its partitioning in the broccoli plant was significant (P < 0.05) in both years. Yield and biomass data revealed that 42 000 L MS·ha⁻¹ application rate plus supplemental N sources can be recommended under the soil and climate conditions of the Canadian Maritimes. The concentration of salts in MS is an application rate limiting factor.