Prepared by Anastasia Kubinec, MAFRD Oilseed Crop Specialist
Sunflower planting was spread out in 2014, which means flowering and dry-down will be as well. The chart below gives and indication to the amount of time it will take the crop to reach R8 to R9. This is a guide only. Sunflower development and dry down is based on temperature. If August is all above 25C during the day and doesn’t go below 10C at night, the sunflower crop will develop much faster than this!
From August 5th to 31st, regardless of location, there is typically 275-320 Sunflower GDD accumulated in Manitoba. To get from R5.1 to R9 the crop needs 393 GDD.
|Sunflower Stage||Sunflower GDD (Celcius)|
*Sunflower GDD= (Tmax+Tmin)/2 – 6.7C
Example = ((25+10)/2)-6.7=10.8
For more information, contact NSAC agronomist at (204)750-2555 or MAFRD Oilseed Crop Specialist at (204) 750-2717
Standardized Growth Stages described by Schneiter and Miller. 1981. Description of Sunflower Growth Stages. Crop Science 11: 635-638
Graph Developed by MAFRD Crops Knowledge Centre