As farmers are signing contracts to grow Canola in Kentucky, there are some general observations from previous research and from current farms on what appears to result in the best odds for successful Canola yields. 

Planting date

To avoid problems such as fall bolting or insufficient vegetative growth, the ideal planting window for western Kentucky is September 15 to September 25. Planting during this period provides a balance between adequate growth and minimizing the risk of premature stem development before winter.

For successful overwintering, canola requires a minimum of 8 weeks of growth between planting and the first frost. This allows the plants to develop a strong root system and adequate leaf area before entering dormancy.

Seedbed Preparation

Canola performs best in medium-textured, well-drained soils with a pH between 6.0 and 7.0. Successful germination and establishment depend heavily on a properly prepared seedbed, ideally one that is free of large clods and excessive crop residue. Fields with heavy residue or large clods can lead to poor seed-to-soil contact, irregular seed depth, and the development of "necks" in seedlings, all of which hinder germination. In Western Kentucky, most growers use tillage to prepare their seedbeds before planting canola. In most cases, a single shallow tillage pass, sufficient to break up crop residues (especially corn), incorporate pre-plant fertilizer, and apply residual herbicides, is adequate for preparing the field.

Some farmers have been successful by burning off corn residue and not tilling. They have achieved excellent germination, ideal stand counts, and successful crop establishment. If you choose to burn crop residues as part of seedbed preparation, exercise caution, as fire-related damages are typically not covered by insurance and may pose serious liability risks. If canola follows corn, but tillage and/or burning the crop residue is not an option, using aggressive row cleaners could provide residue-free environment for canola to establish successful stand. 

Moisture is essential for germination, but the timing of rainfall after planting is especially important. If heavy rain is expected shortly after seeding, it may be wise to delay planting. Excessive rainfall can lead to soil crusting or burying the seed too deeply. Rainfall can cause seeds to be pushed deeper into the soil, and when seed depth exceeds one inch, the risk of poor or failed germination increases significantly and warrants a total replant or replanted patchiness. A well-prepared seedbed that absorbs rain evenly can reduce this risk, forming a firm, moist surface that promotes rapid emergence. 

Seeding rate

As a rule of thumb, aim for 4–7 plants per foot of row in 15-inch row spacing, or 3–4 plants per foot in 7.5-inch row spacing. Canola hybrids vary in seed size, typically ranging from 60,000 to 90,000 seeds per pound. 

Assuming an average seed size of 80,000 seeds per pound, a seeding rate of 3.2 pounds per acre is required to meet the target plant population. In Western Kentucky, farmers have used rates ranging from 2.9 to 3.5 lb/ac, resulting in pre-winter stand counts between 120,000 and 174,000 plants per acre.

The lowest stand count and highest seeding rate were observed in a no-till field in Henderson, where poor establishment was attributed to residual herbicide washout, competition from volunteer soybean, and the possible effects of Hurricane Hélène.

In general, whether using a wheat drill or a modified soybean planter with a 90-cell plate, setting the seeding rate at 3.2 lb/ac is a reliable standard for achieving a competitive stand. If the seedbed is well-prepared and severe post-planting rainfall is not expected, the rate can be safely reduced to 2.9 lb/ac without sacrificing stand quality. Literatures suggest that a harvest population of 4-12 plants per square foot is optimum for good growth and that significant yield differences do not occur if the harvest population does not drop below one per square foot (never recommended though). 

Seeding Depth and row spacing

The optimal seeding depth for most conditions is around 0.75 inches (3/4 inch), which provides a good balance between moisture access and rapid emergence. Planting deeper than 1 inch can delay emergence and could result in uneven stands. 

In dry soils, it may be necessary to increase seeding depth slightly, up to 1 inch, to ensure adequate moisture contact. However, planting deeper than 1 inch is generally not recommended, as canola’s small seeds lack the energy reserves needed to emerge from greater depths.

Under favorable conditions, such as a firm, moist seedbed, canola can be planted as shallow as 0.5 inches (1/2 inch). Seed placement is vulnerable to post-planting rainfall, as raindrops and surface water can push them deeper into the soil, increasing the risk of poor emergence.

Achieving consistent seeding depth requires optimal down pressure and controlling planting speed. A planting speed of no more than 5.5 miles per hour is recommended to maintain uniform depth and minimize seed bounce. In Kentucky, growers typically seed canola at depths ranging from 0.5 to 1.25 inches, with the deepest placements (1.25 inches) observed in no-till systems, where uneven soil often necessitates slightly deeper seeding.

Canola can be planted in a wide range of row spacings, from 7.5 inches to 30 inches. Similar to soybean, canola has some ability to compensate for missing plants by branching out and filling gaps left by failed neighbors. However, excessive plant loss or overly wide row spacing can lead to reduced canopy closure and increased weed pressure, especially during early growth stages.

Row spacings of 7.5 inches and 15 inches have consistently resulted in good stand establishment and rapid ground cover in spring, helping to suppress weeds and conserve soil moisture. In a side-by-side comparison in Ballard County, Collin Coooper tested the effect of autonomous planter and row spacing on canola yield. Canola planted in 30-inch rows failed to adequately cover the soil surface during the flower stage, making it a less favorable option for crop establishment and overall productivity. In his field, a 30-inch row plot (0.90 acres) produced an average of 50bushels per acre. In comparison, a 15-inch row plot (0.82 acres) produced 62- bu/ac and a 10-inch row plot (0.85 acres) produced 61 bu/ac. These results indicate that 15-inch row spacing was best for canola production in this Kentucky trial.

Winter survival

A meta-analysis of meteorological variables influencing winter canola survival classified Kentucky as part of a region with medium to high survival potential (Secchi et al., 2021). As illustrated in Figure 3, winters in Western Kentucky are generally not severe enough to cause significant winterkill, especially when moderately winter-hardy hybrids are used.

With the release of semi-tolerant hybrids, winter survival in Kentucky now depends more on management practices than on extreme weather conditions. Canola should reach rosette stage (at least 6 true leaves and 8-10” inches tall) before the onset of winter frost. Planting too early or too late, or misapplication of nitrogen (N) fertilizer, can result in excessive or insufficient fall growth. Both excessive and insufficient growth will increase vulnerability to frost damage. To minimize winterkill risk, it is essential to adhere to optimal planting windows and base N fertilizer applications on soil test recommendations. Strategic nutrient management and proper timing will help ensure plants enter winter in the ideal growth stage for survival. 

Weed Management

Seedbed preparation is also a critical window for effective weed management, particularly through the application of residual herbicides such as Trifluralin or Command. These products have demonstrated consistent effectiveness in controlling henbit and other broadleaf weeds during the critical early growth stages of canola. At times, timely post-emergent weed control is essential as well. Studies have shown that canola emergence to 4 leaf stage is the critical window for weed control and often results in the best ROI. 

If canola follows soybean rotation, controlling volunteer soybean is just as important as managing other early-season weeds. Observations in Henderson, Kentucky, have shown that warmer-than-average temperatures in November can extend the growth period of volunteer soybean, making it a strong competitor with young canola plants and significantly reducing stand quality. Soybeans will die after a hard freeze, but their competition before that can cause reduced Canola stands.

Table 1. List of canola herbicide-tolerant systems. 

Fertility management

Finally, nitrogen (N) management is key to achieving balanced growth. Canola is a nitrogen-intensive crop, and N management is a key factor to consider for successful production. In AGR-1, N recommendations include no more than 30 lb N/acre in the fall and up to 120 lb N/acre in February and March for canola following corn, soybeans, small grains or fallow land. 

Early planted canola requires only a small portion of its total N in the fall since it has sufficient time for growth before winter. Applying excessive N in the fall can lead to excessive vegetative growth, reducing winter survivability. On the other hand, later-planted canola should receive a higher fall N application, up to 40% (45 lb N/acre) of the total N requirement, to promote rapid growth and ensure plants reach the rosette stage before winter dormancy. 

Diammonium phosphate sources, such as DAP (18-46-0), commonly sold in Kentucky) and MAP (11-52-0, sold in Kentucky to a lesser extent), provide N without causing damage to small seeds and seedlings. N supplied through MAP and DAP should be considered a part of the total N rate. It is worth mentioning that growers have used up to 46 lb N/acre for canola following corn with negligible effect on canola winter survival. 

If manure or chicken litter or other manure source is being applied, get a nutrient analysis of the manure before application. Account for that nitrogen when considering N applications to Canola. 

Resources:

Secchi, M. A., Bastos, L. M., Stamm, M. J., Wright, Y., Foster, C., Messina, C. D., & Ciampitti, I. A. (2021). Winter survival response of canola to meteorological variables and adaptative areas for current canola germplasm in the United States. Agricultural and Forest Meteorology, 297.  https://doi.org/10.1016/j.agrformet.2020.108267