Seed winter canola so that plants develop 6 to 8 leaves and an adequate root system (1.25 cm (0.5 in.) diameter) before winter. Adequate fall growth will improve winter survival and reduce risk of frost heaving. Winter canola needs a minimum of 600 Growing Degree Days prior to a hard frost (average daily temperature below -2°C). Generally, a seeding date of September 1 is appropriate for all areas south of Muskoka. Seed winter canola as early as August 20 in northern and eastern regions, or as late as September 10 in southern Ontario. Delays beyond these dates greatly increase the risk of winterkill. Winter canola is not recommended in regions north of Muskoka.
Some varieties of winter canola may bolt in the fall if they are seeded too early and will not survive winter if they are in reproductive growth stages. However, some varieties have a vernalization requirement and do not bolt in fall. Even if a variety does not bolt in the fall, seeding very early and having very large plants ahead of winter may increase the risk of injury or winterkill because as more leaves are produced the plant’s growing point (crown) becomes raised above the soil surface where it is less protected. Speak to the seed dealer about planting dates before seeding.
Dry weather following planting can be an issue when seeding in August or early September, resulting in delayed emergence. Prepare the seedbed with a minimum of tillage to conserve moisture and pack following planting to ensure good seed to soil contact.
When winter canola is planted after cereals, chaff and straw must be spread uniformly during cereal harvest to reduce large clumps of residue, which negatively affect canola establishment. Tillage coulters and disc openers must cut cleanly through residue to ensure good seed placement and seed to soil contact. Where seedlings emerge through thick residue, they may set their crown (growing point) above the residue which increases the risk of winterkill. Residue on the soil surface harbors slugs which are a significant cause of stand loss. Attempts to grow winter canola in high residue environments often results in extreme stand loss caused by slug feeding at the time of emergence.