Increase (in the number of fans in a clump)
If my memory serves me well, Munson told his daylily helpers that if his clumps were not divided each year then they suffered. I assume that he meant the rate of increase declined as well as both bud counts and rebloom, etc. I also assume that he had an average increase ratio of near 8:1 per year since he grew his daylilies in Florida and that he grew them under near-optimum conditions.
My assumption would be that at clump sizes over 10 fans the fans begin to compete with each other noticeably when analyzed objectively; they probably shade each other a bit and divide fertilizer and water among all the fans, so get about 1/10 each (or less for larger clumps) of what is being provided by the grower.
What do I mean by analyzed objectively?
Have many clumps of cultivar x. Divide them so there are 10 clumps with 10 joined fans each, 10 clumps with 2 joined fans each and say 10 clumps with 5 joined fans each. [It might be possible that reducing the number of clumps to 5 would still provide a good test but I would use 10 or more clumps.] Give all clumps the same measured amount of water and fertilizer at the same times (in other words treat them all identically) for the entire test period. On the same date each year for say three years, count the number of fans in each clump. At the end of three years analyze the results. The test could be done with clumps of single fans but then the distances between fans in each "clump" would have to be measured and be consistent for all clumps.
