Q. How do I know if a mature stand of daylilies needs division? When and how do I do this?
A. You can consider dividing your daylilies if they appear too densely crowded, if their flower production is less than normal or if they haven’t been divided in 10 years. By digging the clumps in late August to early September, you give the new divisions a chance to settle their roots before frost arrives. Water the plants well a day or so before you dig and choose a cool, cloudy day if possible.
An established clump will have an extensive, fibrous root system. Using a sharp spade, dig the clump, shake off excess dirt and lay the plant on its side. With the spade or an electric hedge trimmer, make clean cuts through the foliage and roots, either halving or quartering the clump. Trim off any broken roots and foliage and replant each section in your garden. Provide even moisture for these plants right up to frost. Daylilies prefer full sun but will tolerate partially shaded conditions.