Wheatgrass

White fuzz around the base of the blades

Nine times out of ten it is root hair rather than mould. Root hair is fine and white, sits only on the roots, and vanishes when misted. Mould spreads across the grain and the tray surface, and it smells sour.

Fix: If it is mould, sow thinner next time, water less, and get air moving over the tray with an open window or a small fan. Rinse the grain properly before it goes down.

Grain smells sour before anything has sprouted

Over-soaked. Wheat left sitting in water ferments.

Fix: Soak for 8 to 12 hours, no longer, then drain and rinse twice a day until the roots show. A soured batch will not recover, so start again with fresh grain.

Patchy tray, with some grains sprouting and others sitting on top doing nothing

Poor contact with the medium, or too much light too early. Wheat germinates in the dark, pressed against damp soil.

Fix: Spread the soaked grain in a single even layer, press it down into the medium, and cover the tray for the first three days. Uncover once the shoots are an inch tall.