Day lily flowers bloom for only one day as their name suggests, but when a garden bed full of these bright flowers is in bloom it will remain a strong point of color in the garden during the late spring and early summer months. Yellow day lilies are herbaceous perennials that go dormant in the winter time. These vigorously growing flowers should be divided every three to four years to improve flowering and as a means of propagation.
Cut the foliage back to 6 inches above the ground in mid-summer after the flowers die back. Use a pair of sharp shears to make clean cuts.
Dig straight down using a shovel or garden fork about 3 inches from the edge of the yellow day lily clump. Pull back on the handle lifting the clump from the soil.
Brush the soil away from the day lily root clumps. Pull the rhizomes into sections with each section having three fans where the foliage emerges from the roots.
Replant the divisions at the new planting sites. Dig holes deep enough to bury the root section and 1 inch of foliage under the soil line. Press the soil back around the divisions and soak the area to a depth of 4 to 6 inches.
You can also plant the divisions in pots to give away or keep indoors. Use standard potting soil and bury the root divisions at the same depth as you would outdoors in the soil. Use 6- to 8-inch pots for individual plants.