Sunflower Planting Dates. KS respondents planted sunflower from before May 1 to after July 31, but the majority was planted in June and early July (Table 7). Some of the late planting dates in KS may be due to double cropping following winter wheat harvest. Sunflower was planted earlier in the northern states than in KS. MN respondents planted most of their acreage in the period May 11 to June 10, with over half of total acres planted May 21-30. ND respondents planted most of their acreage in the period May 21-June 10. SD respondents planted most of their acreage in the period May 11-June 10, with the greatest percentage planted in the period June 1-10.