I'm certainly no expert in beardless culture, either, but, mine are grown in sandy loam soil (amended pretty heavily at planting time with "peat soil',and "river muck") , mulched with "pine straw" (which helps bring the ph in line, although I still need to add quite a bit of sulfer). I do twice-yearly soil tests for ph, but don't check for nutrients or trace minerals. The pine needles (I think) add quite a bit of organic matter, and trace minerals , as they break down (all stalks and foliage are removed from the plants at the end of the season, and disposed of), and the "new, organic soil" being created "helps" to keep them at the correct depth, and also ties up a lot of nitrogen, while "breaking down"...so I fertilize , quite heavily, twice a year (home made mix of "about" 15-8-4). With "irrigation"..."water out of the hose", vs. 'water that came down the creek", you're more apt to be "nutrient shy", as well as getting the "buffer" ph out of whack, so you need to stay on top of your soil tests, and amendments......with lots of rain, or irrigation, you'll get more "nutrient leaching", so, again, more frequent feeding and amending for ph will probably be needed, as well as seeing if the trace minerals,,,iron, especially ...are sufficient. As to division....mine are starting to show the need for some ! They have been in place 8 years, with the only "division" being the "stealing" of some for sharing!...But, when I do that, I try to "replant" a small chunk to the "inside" (the "bare spot"!), but that is only "delaying the issue "
! Since our soil is so "naturally sandy> and doesn't hold water well, when I "built" the bed, the JI's area was excavated to about 2 feet deep, and a layer of rubber roof membrane was laid out, then the trench was refilled with the "peat, sand, river muck" mix....that gives a barrier to stop the moisture from "leaching down"...the mulch helps keep it from "moving up", so maintain the soil moisture ids much easier.