When too much nitrogen is applied, the plant grows at the expense of the flowers, and the foliage becomes weak and falls over. Diploid daylilies have the normal chromosome number in the cells of the plant. Chromosomes contain genetic information which determines the characteristics of the plant. Diploid daylilies may have a more graceful and relaxed form. The flowers tend to have softer colors compared to the tetraploids.
Tetraploid daylilies have double the normal amount of chromosomes.
The plants tend to be husky and have more blooms per flower stem. The flowers are usually larger and more intense in color than the diploids. The most recent addition is the miniature daylily. Daylilies are considered miniature when they have flowers that are three inches or less across. Generally the foliage for these cultivars is 24 inches tall or less, but plant height is not considered as part of the classification.