Establishing an adequate plant stand is one of the primary challenges in the production of canola (Brassica napus L.), and plant population strongly affects crop morphology. We tested the hypotheses that i) pre-plant application of liquid dairy manure (LDM) improves crop establishment more than a fertilizer with similar nutrients, and ii) plant morphological changes correlated with low-density plant stands enhance crop tolerance of mid-season water stress. In greenhouse studies both LDM and fertilizer treatments enhanced seedling vigour over the untreated control, but in some cases percent seedling emergence was higher with LDM than the fertilizer treatments. Enhanced seedling emergence with LDM was not found in field trials, even at sub-optimal seeding rates. In a high-yielding greenhouse trial, low plant density shifted much of the pod load from main racemes to branch racemes, but this morphological change did not significantly reduce yield loss under water stress.