Every year I get asked about late planted cotton that is still active blooming come September. Will these blooms make a boll that is harvestable? Last year I was able to participate in a multi-county study collecting data on late cotton blooms. The data was presented in a poster at a Beltwide this past January. You can look at it here:
Here are a few graphs pulled from the poster:
In Summary: the environmental conditions experienced during 2020 allowed blooms to mature through the third week of September. 2020 appeared to be a normal year and one year of data supports the hypothesis that positions which bloom between September 5 and 15 are likely to mature. Every year the weather is a little bit different so it may vary across conditions and locations. We are repeating the study this year to see if it remains the same.