Mary - It varies by cultivar, depending on whether they multiply quickly or slowly. For cultivars that multiply quickly, you might just want to keep four or five fans. For those that multiply more slowly, you might keep 6-8. Personally, I never get rid of the middle parts. I divide the clumps into sections of 3-4 fans and then replant three of the sections together, and I plant other 3-4 fan divisions elsewhere in my yard, or give them away to freinds and neighbors.

Debra

I can't even begin to give a concise answer. First, Some of mine have NEVER needed thinned or anything, rarely increase, and go on and on just fine such as Purple Riot and Kirsten's Corsage. Some need thinned about every 5 years or so. Others perhaps 10 years. Ones that very slowly increase I would keep far more than ones that increase fast.

For the ones that increase quickly, I usually leave about 4. I don't worry about inside the clump or outside the clump plants. I pick large ones because they have the best chance of blooming next year. I also have some huge clumps of ones that increase rapidly but bloom well anyway. I leave well enough alone.

My Primal Scream is very slow to increase, yet it slowed down blooming two years in a row So all I did for it was dig it up, put fresh soil, put every plant back in the ground. The next year it bloomed well and increased by one or two.

Some aren't worth your time. I had Isolde. It needs done every 5 years, but the first 2 years after being split it hardly blooms. Then it has 2 decent years, then slows down and needs split again. This year I dug it up one last time and I'm done with it.

Basically you need to learn how each one does and go accordingly.

Brad

I have only been growing them in hot humid Alabama (where if you stand still too long you will be covered in weeds, vines, small trees etc... I will be dividing four that have bloomed poorly for a couple of years and this is the first time I have needed to divide anything in my garden. I would say it varies from plant to plat and area to area.

ksy

Hi Mary_rockland, I live in S. W. Ontario near London Ontario and we get some wicked heat and droughts here . I pretty much have to concur with all of the posters above. It really is an individual thing with each plant . Lots depends on soil conditions , water , situation ( I.e. shade , part shade or sun) and of course the plant itself . Once you have a plant for about 3 years , I find that that is a good time to keep an eye on it to see if the blooms are diminishing . I am not sure who said First year they sleep , second year they creep , third year they leap . By the fourth or fifth year I find that if a plant is slowing down on blooms , that is usually a good indicator that a plant needs to be split .

I also do not take anything out of the middle of the clump to toss ....but divide it in several sections like Brad suggested and then plant in other spots or give away . I don't find my daylily clumps die out in the middle like my Siberian Iris do.