I have been growing daylilies for nearly forty years. My first encounter with the genus was with the clone of H. fulva known as 'Europa'. My grandmother had this old-fashioned ditch lily growing here on the farm. There is no daylily more vigorous than 'Europa', so perhaps I will always be biased to what a daylily should be in regards to vigor and hardiness.
My first cultivars came from Gilbert H. Wild and Sons of Sarcoxie, Missouri. Throughout my childhood and into my teens, most of the daylilies we grew in my family came from the Wild's catalog. Most were Wild's introductions, though some were cultivars bred by other breeds that the Wild family sold through their catalogs. Over the years, I have heard disparaging remarks about the Wild cultivars from some daylily hybridizers. Usually the line of reasoning being that the Wild cultivars are somehow less than other breeder's cultivars because they weren't pedigreed or because they were mass produced and sold in large numbers, etc. My experience would indicate that they are not generally inferior. Some in fact are extremely good daylilies and are generally very strong cultivars that survive well, are vigorous and have surprisingly modern forms, many of which we would now call "unusual form".
Other cultivars from the Wild's catalog that we ordered and grew were from such breeders as Hall, Fay, Flory, Spaulding, Stout, etc. So my early experiences with daylilies were of older, very hardy, strong daylilies that displayed a lot of vigor and survivability. I only ever had one major problem daylily cultivar from the Wild catalog. It was a plant called 'Edged In Gold' and it died the year after it was planted - a foreshadowing of things to come in later decades.
In my twenties, I began to order daylilies from other sources. These included many Munson cultivars as well as other newer daylily cultivars from the late 80's and early 90's. Most of those daylily cultivars were strong growers, but a few showed problems I had never seen that were a surprise to me at the time. These problems seem to be amplified in many daylilies now.
As I entered my thirties around the year 2000, I again went through a phase where I bought a good number of daylilies. My focus at the time was on pink and lavender colored cultivars. While a few of these were good, strong plants, a great number were of surprisingly bad coloring, poor growth and/or poor performance. I have very few of those still growing in my garden as of this writing.
Around 2004-2005, my aunt had built a new house and started buying some of the newer piecrust type tetraploids. A few of these were nice plants, but the majority left a lot to be desired. This was our first introduction to really bad daylilies that displayed multiple problems within each cultivar.
In 2010, I began to actively and intentionally breed daylilies and added a large number of cultivars through to this year (2012), in order to bring in diverse, new genetics. In total, we have now grown over five hundred cultivars in the course of nearly four decades. We still have over three hundred cultivars, though that number is being thinned constantly. It is my goal to cull those numbers down considerably. I expect to choose perhaps 30 cultivars or fewer to be my major foundation breeders for strain development. My recent accessions have been to allow me to find a small number of excellent breeders to use with the small number of excellent breeders I still have around from the last thirty + years of semi-obsessed daylily collecting.