It's my own belief that scape/stalk strength isn't solely determined by genetics. Growing conditions are outside factors that affect how they grow. Temperature, moisture, rate of growth, wind all come into play. So some years I've noticed plants do really well, but in other years they perform miserably. My observations aren't with daylilies as much as with other plants, but I'd expect to see the same from any plant. Give food and conditions for rapid growth along with seesaw temperatures with some wind and I'd expect some scapes would be crawling on the ground like snakes.
