Sowing and establishment of brassicas

Sowing Brassicas

  1. Allow the paddock to get a pasture or weed cover of 2000 kgDM/ha.
  2. Spray out with glyphosate at the correct label rate.
  3. Three days later, hard graze to remove vegetation prior to cultivation or drilling.
  4. If cultivating, use conventional farm practices that result in a fine, firm, residual-free seedbed.
  5. In cultivated situations, seed can be broadcast, then harrowed and rolled. (If using Cleancrop™ Brassica System, then apply Telar® post sowing).
  6. Best practice for direct drilling is to use a double spray programme. The initial spray out with glyphosate and usually a broadleaf herbicide occurs about 6 weeks before sowing. A second spray with glyphosate occurs prior to sowing to remove germinating seedling weeds (if using Cleancrop™ Brassica System, include Telar® with second spray), usually includes an insecticide and may require slug bait. Seed is sown at approximately 10 mm depth and then rolled. Seek advice for the appropriate use of chemicals.
  7. Once the crop is sown, it is important to monitor the crop and apply the appropriate herbicides and insecticides to remove any weed or insect problems.
Southland Sales Agronomists Brain Young and Mike Fairbairn and farm owners Quentin and Andrew Miller standing in a crop of Cleancrop™ Hawkestone swedes.

For products within the Cleancrop™ Brassica System range (Cleancrop™ Hawkestone swede, Cleancrop™ Firefly kale, Cleancrop™ bulb turnip, Cleancrop™ Toto turnip, Cleancrop™ leafy turnip and Cleancrop™ rape), follow the latest Cleancrop™ Brassica System Guide for best practice management and the stewardship plan.

Learn more about the Cleancrop™ Brassica System

Cleancrop™ Hawkestone swede.


Swedes should only be used in a first crop situation to prevent dry rot infection. A second crop alternative is kale.

If clubroot is likely to occur, Hawkestone or Clutha Gold are the better alternatives to other swede cultivars. Under high pressure from clubroot, kale should be used.

If there is a high risk of either dry rot or clubroot infection in the second year, it is recommended to sow the paddock in either a pasture or cereal crop.

In environments where brassica crops can be exposed to very cold conditions post-sowing followed by increasing temperatures, swedes should be sown no earlier than 20 November.

Earlier sowing combined with weather conditions can cause ‘vernalisation’, which means the plant believes it has been through winter and subsequently produces a seed head.


Fertiliser requirements should be based on soil testing.

High yielding brassica crops have a large nutrient requirement. The nitrogen (N) requirements can range from 250 to 500kg N/ha. While total crop requirement for phosphorous (P) is quite low, it is vital during establishment and for shallow rooting brassicas. The application of P in a base dressing and down the spout at planting will provide good response particularly on low P soils. Growing brassicas on effluent ground may allow significant reduction in fertiliser inputs but again this should be on the basis of soil testing and knowledge of crop requirements.

The soil pH level should be at least 5.6 and ideally between 5.8 and 6.2 for most brassicas. Crops should have at least 40-60 kg phosphate/ha available at sowing.

Paddocks should have low soil sulphate levels. After grazing, a light application of nitrogen will greatly increase yields of subsequent growth. Use of nitrogen may increase problems of high crop nitrate content; test levels before grazing.