Q. Is it always important to know the parentage of the daylilies we use for hybridizing?
A. It is always better to know the parentage then to not know the parentage, but knowing the parentage isn't as useful as many people think.
If you are buying a daylily for landscaping, then you should buy it because you like it and it fits into your landscape plans. Knowing the parentage is a nice extra, but there is no reason for not buying a particular daylily just because its parentage isn't known.
If you are hybridizing, then knowing the parentage can give you some idea of the plants potential, but it only gives you an idea. A plants breeding potential is measured by evaluating the progeny produced by the plant, not by its parentage. By making various crosses and evaluating the offspring you can figure out what the plants breeding potential is. Knowing the parentage can, however, give you some clues as to what to expect, but you wont know until you actually make crosses and look at the progenies.
The reason the parentage only gives you a clue is that each parent in a cross only contributes half of its germplasm, but you don't know which half each progeny gets. Each seedling from a particular cross will be different, even if they look similar. Relatively few of a plants genes can be observered in the phenotype. Plants that look similar can be quite different in their breeding potential even though they have the same parentage.
If you are buying daylilies for hybridizing you may want to consider the parentage, but if you are developing a long term hybridizing program where you are developing your own breeding stock, then you should buy those daylilies that have the traits you are interested in, because it is particular traits that you want to bring into your breeding program. For example, if you are hybridizing winter hardy deciduous daylilies for the northern market and you want to incorporate the beauty of the Florida daylilies, then it really makes little difference what specific Florida beauty you use because your goal is to incoporate the desirable genes and then develop your own breeding lines.
On the other hand you can do what I call check book hybridizing. In check book hybridizing you buy the latest and newest one hundred dollar daylilies from the top named hybridiziers, make various crosses between these daylilies in hope of producing your own one hundred dollar daylilies and then next year repeating the whole process over again. No attempt is made to develop your own breeding program. In this type of hybridizing you should consider the parentage carefully because your goal is to maxamize your potential with as little work as possible.
Although knowing the parentage of daylilies you are bringing into your own hybridizing program isn't that critical, knowing the parentage of the breeding lines you produce is important and you should make serious effort to keep track of the parantage of your own seedlings to the extent possible. Knowing the parentage will help you decide which lines to cross to carry along your breeding program. However, this depends to some extent on the breeding scheme you are using and your particular goals. After awhile, however, the parentage can become so complex and cumbersome that it really doesn't give you much useful information.
I have yet to buy a daylily because of its parentage and I've bought many daylilies with limited or no parentage. I do try to keep accurate records of the first generation crosses as these crosses give valuable information to help evaluate a plants breeding potential. After that I often intermate the F1 seedlings within particular crosses, but rarely make any attempt to keep track of which seedling gets crossed to which other seedling. I still know the progenies are F2 seedlings of a particular cross. It rarely makes much difference to me to keep track of all the possible different seedling crosses I can make because most of the seedlings used as parents to carry along a breeding line are eventually discarded. This is a workable compromise that gives me the basic information I need while saving the time involved in keeping tract of long, overly detailed parentages.
As a general rule buy daylilies for hybridizing because they have the traits you want and then keep track of the parentage that gives you as much information you need while minimizing the amount of time needed to keep track of parentage.