Daylilies should be divided at least every few years in order to keep them blooming well. After a while the roots become overgrown and hinder the plant’s ability to produce as many flowers. They should be divided in the late summer or fall, after they have finished blooming for the season.
The typical method of dividing daylilies is to dig up the whole plant, cut it into two to four sections with a spade or knife, and replant those groupings individually. It’s a simple way to take one large plant and turn it into two or four plants. Some people are happy with that.
Daylilies can be divided into even more sections pretty easily. It takes a little more time than just cutting the group into a few pieces, but the result is many more plants! If you have a backyard nursery, or you just like the idea of having even more daylilies, you should try this out.
Instead of just cutting the large clump into a few pieces, you want to take the whole thing and shake the soil out of the roots. If it’s too large to shake, split it into a couple of sections first. Separate each fan, or individual plant by carefully pulling them away from the grouping one at a time. Try to untangle the roots a little to separate the entire fan, roots and all. Some clumps may be rootbound and seem really stuck together, but they are very resilient. Tearing or cutting some of the roots while separating them won’t hurt.
Cutting the tops and roots down to 4 or 5 inches in length before replanting makes the divisions more manageable. Pruning the roots will also ensure that they aren’t bunched up when planted, and will actually stimulate root growth.
After dividing the daylilies, it is a good idea to allow them to sit out and air dry for a few days before replanting them. Without this drying period, the wound on each fan where it was separated from the rest will be a good environment for disease, insects or rotting. Professional growers will leave the cuttings out in the sun for a few days to allow the wound to callous over and dry out. Some even throw them in a huge bin and leave them there for the whole winter, in a cool building such as a barn.
Daylilies will grow best if planted in the ground, and 6-8 inches of space between the cuttings will do. Not only will this save a lot of room, but when the plants start to fill in they will block a lot of the sun, making it harder for weeds to grow.