Experts and BHG readers answer.
Dividing short lived Perennials, daylilies didn't come back.
Both plants should be long-lived with proper division. Coreopsis should be divided every few years to retain their vigor. Daylilies need to be divided every 3-5 years or they will stop blooming. If a few haven't come back, perhaps they are planted to heavy soil or clay soil. Daylilies prefer well-drained conditions.