Daylilies can be dug up and cut up with a sharp spade or large garden knife. However, I prefer to wiggle the roots apart with my hands, or with the additional help of a long screw driver or two. You will get divisions with more roots intact, and less cut surface area for disease to enter the tubers.
You can help this process along by soaking the daylilies overnight in a bucket of water to soften soil caught up in the roots.
Then let them have it with a strong spray of water to loosen the remaining soil. Wiggle them apart with your hands, using more sprays of water as needed. Ideally, you could divide a clump without ever breaking any crown or roots.
Photo: using strong spray of water to get dirt off roots prior to dividing. Photo courtesy of Char.
John Rice, of Thoroughbred Daylilies in Paris, KY, told me about his favorite hose nozzle at least 10 years ago. I bought one and it is still going strong, unlike most of the nozzles from the big box stores. It's a Bon-Air Ultimate Hose Nozzle. It looks a bit like the end of a fire hose, and puts out an adjustable spray that you can use for lots of purposes! One of those classic tools for the garden.
Find more information about this particular tool at
Bon-air Ultimate Hose Nozzle