Cultivation principles in vegetable brassica production
Crop rotation is important to avoid soilborn diseases such as clubroot, xanthomonas, and verticillium.
While not always practicable, rotations of at least 4-5 years between brassicas are advisable to minimize build-up of these diseases. Growers should try and utilize as much of the residual nutrient resource by ensuring a fast turn-around into the next crop, adjusting fertilizer practices accordingly.
Most common practice is to raise seedlings in plugs in the nursery. These are planted out after 3-5 weeks. Direct seeding, while it can help minimize bolting in fast growing climates, usually creates variation in the maturity of the crop, increasing the number of cuts required.
When planting out transplants it is important to minimize transplant shock. Thus, soils should be well prepared and warm, with adequate moisture or irrigation available. Soil temperatures must be greater than 10°C (50°F) – ideally around 15°C (59°F). Transplanting, when daytime temperatures reach 30°C (86°F) and above, should be avoided.
Spacing varies according to brassica type, the speed of growth and harvest method . If the aim is to produce smaller heads, particularly in fast growing conditions, then a denser spacing is used. Wider spacing produces larger heads.
