Mustard

Excellent for weed seed control and cleaning up some harmful soil fungi. Contains high levels of potent glucosinolates (GSLs), the biotoxic compounds that make mustard spicy and act as natural fumigants. Mulching breaks the plant cell walls, releasing GSLs into the soil when the plant material is incorporated. Very fast growing and prefers moist soil. Dig or plough in after 4-6 weeks and prior to flowering. Sow from September through to April. Lightly cover seed with soil.

North Island: You can sow slightly later (April–early May) due to milder winters.
South Island: Aim for March–April to allow enough establishment before cold sets in.