This reminds me of taking soil samples for testing. It is recommended to take 10 1/2 cup samples from various locations in the test area, even a small planting bed. By mixing the samples up thoroughly the differences through-out the bed will be “averaged out” and the final 1 cup sample from that mix will be generally representative of the “average” conditions of the whole bed.
It might be possible, with a fair amount of effort and cost, to generate a soil map of a test bed by performing a large number of soil tests. The more the soil differences are known the more they can be taken into account when testing, allowing for increased accuracy.
Additionally, the soil uniformity of a test bed could be increased. One could thoroughly rototill the soil, test the soil, and add amendments as needed to meet particular deficiencies in particular areas. If this process is repeated for several years one could that imagine soil uniformity could be greatly increased.
Of course factors other than soil variations can also present different growing conditions to daylilies planted right next to each other. For example, I have two daylilies planted in the same bed, 3 feet apart, in afternoon shade. However, I noticed that for most of the summer one of them by pure chance happened to be in an exact spot that received much more dappled afternoon sunlight than the other. One might be able to mitigate this by placing the test bed in full sun or ensuring somehow that shade, when it occurs in the test bed, is homogeneous. One can imagine still other factors, such as actions of wild insects and moles, randomly affecting one plant more than another.
