The best time to cut back daylilies is in mid-summer or early fall after the foliage has turned brown. The foliage should be cut back to 2 to 3 inches above the ground.
When cutting back daylilies, the larger clumps can be divided to propagate new plants. The established clump should be dug up and divided, leaving the roots intact as much as possible. The new division crown should be placed in the ground at a depth of 1 inch. The roots are then draped over surrounding soil and covered with dirt. The new plants need to be watered often to keep the soil moist to a depth of 8 to 10 inches.