As sunflower planting approaches each spring, a reminder helps producers recall what they are in for. Planting while there is still a risk of frost, is common in May and sunflowers are pretty hardy when faced with spring frosts. First of all, sunflowers will germinate and emerge evenly and quickly when planted into warm soils. They will continue growth at a minimum of 6.7^oC, external temperature, but anything colder and growth will be halted until temperatures warm up and the plant knows that it is safe to grow again.

Sunflowers tolerate early frosts fairly well (-3.3^oC to -3.8^oC) for short periods until the 2-leaf stage (V2). As the plant progresses, it becomes more susceptible to freezing temperatures and up until V6, they can withstand from -1.6^oC to -2.2^oC for short periods. Remember these points when planting and consider delaying planting if there is a risk of hard frost in the future.

Pre-plant incorporated herbicide applications are very effective in front of sunflower planting. Herbicide choices tend to be limited in sunflowers and planning ahead will give the crop a head start. PPI herbicides often do not control weeds that have already emerged, so a glyphosate application may be necessary, depending on the weed spectrum present.

Final plant populations should be the following:

Confectionery: 14,000 – 16,000 plants per acre

Oilseed:

Birdfood: 22,000 – 24,000 plants per acre

Crush (oil): 22,000 – 23,000 plants per acre

Dehull: 20,000 plants per acre

Planting accuracy is very important in row crops like sunflowers, especially where plant populations are so low. A skip between plants is more area for weeds to inhabit and use what fertilizer they have access to. A double acts as a weed to its nearest neighbour and can get choked out, becoming an unproductive plant. Both scenarios impact yield.

See NSAC’s edition of The Sunflower Production Guide for more growing tips and pest information.

For more information on sunflower planting and tips to achieving high quality seed, register for Hot Topics in Sunflower webinar, hosted by Grainews.