My Stella d’Oro daylilies need to be divided. I would like to do it this fall. Do I have to remove and discard the center of each plant like I do with my Sedum ‘Autumn Joy’? Also, should I cut back the foliage after the division?
Make sure the daylilies actually need dividing. Many varieties, especially ‘Stella d’Oro’, can go several years before they need dividing. Check if they are crowded or lack flowers or vigor. Sometimes they just need a bit more deep watering (water that reaches 8 to 10 inches into the soil) especially on hot days or a light mulch to help them retain moisture. They also need fertilizer to keep them blooming happily. This is especially true for larger clumps and those planted in light or sandy soils that leach badly. The best way to determine the fertilizer needs of your plants is to do a soil sample through your MSU Extension office. You can call or go to the office and pick up a soil sample kit. Otherwise a general fertilizer low in nitrogen such as 5-10-10 should be applied a few times throughout the spring and summer.
If you’ve now determined they do need dividing, fall is a good time because the roots will grow rapidly before next year’s flowering. Dig around the clump and make sure you dig up all of the roots, especially if you will be moving the plants to another area. Otherwise a small section of root may produce another plant in the original spot. Shake off the soil so you can see the roots. You do not need to discard any part of the clump unless it is diseased or does not look like it is actively growing; the roots should look white. Cut or break the clump into sections of 3 to 5 fans each. If it is a large clump, you may only want to cut it into quarters. A single section or fan will root, but it will take a long time to form a showy plant.
Cut the tops of the plants to about 8 inches and plant the daylilies at the same level they were growing before. Prepare the soil where you will plant the divisions by loosening it about 1 foot deep. Add organic matter if you have sandy soil. Dig the hole larger than the roots and make a mound in the center of the hole. Spread the roots over the mound, cover with soil, firm it in and water well. Space plants approximately 18 inches apart. You can cover with light mulch, but leave space around the base of the plant so the mulch doesn’t smother it.
Also read: Maximizing daylily blooms