40-60 Days to Termination. Brassica napus, Brassica rapa, and Raphanus sativus. 3 Brassica Classic Trio Cover Crop Seeds. Non-GMO, annual, open-pollinated, winter-killing. This cover crop mix of radish, canola rapeseed, and turnip is ideal for those wanting to reduce soil compaction, improve drainage, and suppress weeds. It is ideally sown in the late summer or fall seasons to winter kill. Although, it may still be planted in the spring to prepare for summer-sown crops. This mix is also forage and grazing-friendly but should be paired with additional feed or roughage for a complete diet. ~7,395 seeds/oz.