Row Width
Ontario winter canola is commonly grown on 38 cm (15 in.) spacings. Row widths of 19 cm (7.5 in.) are also appropriate and are commonly used for Ontario spring canola. Research has not been conducted on row widths in Ontario winter canola. In the Pacific Northwest and Kansas, it is recommended to grow winter canola on narrow row spacings up to a maximum of 38 or 51 cm (15 or 20 in.). Research in these regions shows that yield losses are minimal on 71 and 76 cm (28 and 30 in.) row widths but faster row closure on narrow rows may reduce weed competition.
In spring canola grown on 76 cm (30 in.) rows there may be yield losses of up to 10%. Wide row canola stands may be more variable because the plants will produce many branches and have a longer flowering period. The seed in pods on the first branches may mature long before seed in pods on the last branches. This can make it difficult to time fungicide applications and harvest. Canola plants grown on wide rows may also have very thick stalks which can introduce challenges at harvest.
Seeding Equipment
The goal is to seed winter canola at a rate of 55 to 85 seeds/m2 (222,000 to 343,000 seeds/ac). Air drills, air seeders and row unit planters are commonly used to seed winter canola. Box drills can be used but are less common because of the difficulty in accurately seeding at low seeding rates with small seed. Row unit planters equipped with canola plates achieve more precise rate control and singulation resulting in more uniform stands and are used to plant winter canola at low seedings rates. More precise seeding equipment such as a planter, can reduce seed costs but seed savings alone may not justify costs associated with a new planter or potential changes to fertilizer application methods. Ontario producers using corn planters are planting on 76 cm (30 in.) rows or running the planter through the field twice to achieve 38 cm (15 in.) row spacings. Producers frequently report that sensors cannot read canola seed moving through seed tubes on planters, so monitors do not show how much seed is being planted. Low seeding rates work well in winter canola since winter survival is better at low populations, but because of the risk of stand loss to early season insect pests in spring canola, higher seeding rates are recommended for the spring crop.
Achieving the target canola seeding rates can be a challenge with some older conventional style drills. Calibrate seeding equipment before heading to the field. Ensure that each of the drill’s seed cup openings is set the same. Slow-speed sprockets and/or seed bulking agents can be used with conventional drills to fine tune seeding rates. Bulking of seed with pelletized elemental sulphur, monoammonium phosphate (MAP), MicroEssentials Sulphur + Zinc (MESZ), or corn cob grits are options for improving seeding rate accuracy. Consult the fertilizer section of this resource to understand safe rates of these seed-placed fertilizers. Do not use other fertilizers, or high rates of these starter fertilizers, with canola seed due to risk of reduced seed germination and emergence from salt toxicity.
Broadcast seeding of canola should only be done where there is no option of using a seed drill or other more precise seeding equipment. Broadcasting can be effective when adequate moisture is sustained throughout the germination and emergence period. Some spring canola producers broadcast canola seed with fertilizer onto a prepared seedbed. However, broadcast seeding is not recommended for winter canola because emergence may be slow and small plants may not survive the winter. Additionally, plants emerging in very moist soils tend to be shallow rooted which may result in heaving or poor winter survival. Good seedbed preparation ahead of broadcasting followed by harrowing or packing helps to keep seed depth constant and ensure good seed-to-soil contact. Broadcast stands can be inconsistent in dry years. The advantages of broadcast seeding are time savings and low cost. The major disadvantage of broadcast seeding is uneven planting depth and seeding uniformity. Higher seeding rates (10%–15% increase) are often required for broadcasting compared to drilling.
Seeding Depth
Rapid and uniform emergence is desired. Sowing depth has a major effect on seedling vigour. Seed 1.25–2.5 cm (0.5–1 in.) deep if there is adequate moisture, and deeper if necessary to plant 0.6 cm (0.25 in.) into moisture. Do not plant deeper than 4 cm (1.5 in.). Emergence of seed planted at 4 cm can be decreased by 50%–60% compared to planting at optimum depth. Seeding into moisture will support uniform emergence and growth that will help with timing of weed control, pesticides, and harvest. Dry conditions at seeding or in the following week can increase seedling mortality significantly.
Seeding Rate
Canola is considered a “plastic” plant in that it adjusts to its surrounding environment and can compensate for wide variations in population with very little effect on final yield. The optimum plant stand is 55 to 85 healthy plants/m2 (5 to 8 plants/ft2), however, a stand of 55 plants/m2 has the same yield potential as a stand of 215/m2 (20 plants/ft2). In a higher density stand, the canola plants will produce fewer branches. Higher density stands may be more uniform in terms of pod formation and maturation, where lower density stands with more branching may have a longer flowering period and take longer to mature. Dense populations may have thinner stalks and increased lodging but are more competitive with weeds and may be preferred in spring canola where high flea beetle damage is expected. When moisture is limited, low density stands may not be able produce adequate yields.
Seed winter canola at 55 to 85 seeds/m2 (222,000 to 343,000 seeds/ac). Seeding rates in Ontario winter canola range from under 2.2 kg/ha to 4.5 kg/ha (2.0 lb/ac to 4.0 lb/ac). Winter canola is seeded at lower rates than spring canola to limit plant-to-plant competition ahead of winter. Winter canola that is seeded too thick will result in an increased risk of winterkill because become tall and spindly rather than stout and robust (Figure 1 and 2). Competition also results in plants with crowns (growing points) raised above the soil surface where they are less protected from winter conditions. Heavy competition from weeds or volunteer cereals in the fall can have the same effect.
Figure 1. Plant-to-plant competitions results in spindly plants and raised crowns, increasing risk of winterkill.
Figure 2. Plants that are spaced out by 2.5 cm (1 in.) or more grow to be more robust with plant crowns snug to the soil surface, reducing risk of winterkill.
Canola seed size can vary greatly between varieties. Seed size has not been found to influence rate of emergence or yield. Calculate the target seeding rate in kg/ha (or lb/acre), using the 1,000 seed weight in grams found on the seed tag. Include the percent germination on the seed tag, and the expected emergence in the given field in the seeding rate calculation.
Seeding Rate Example
The seeding rate can be determined by knowing the 1,000 seed weight in grams, found on the seed tag, and using the following formula:
Metric
Seeding rate (kg/ha)
= (desired plant population/m² x 1,000 seed weight in grams ÷ seedling survival rate) ÷ 100
Imperial
Seeding rate (lb/acre)
= (desired plant population/ft² x 1,000 seed weight in grams ÷ seedling survival rate) ÷ 10.4
Seedling survival (final stand)
= % germination (on seed tag) x % expected emergence
Sample Calculation
Using seed size of 5 g/1,000 seeds, 90% germination guarantee on No.1 seed and 75% expected emergence
Seedling survival
=0.9 x 0.75
=0.675
Seeding Rate (kg/ha)
= 75 plants/m² x 5 g ÷ 0.675 ÷ 100
= 5.6 kg/ha
Seeding Rate (lb/acre)
= 7 plants/ft2 x 5 g ÷ 0.675 ÷ 10.4
= 5.0 lb/acre