I'm no expert but we made a daylily bed 2 years ago and planted them approx. 2 feet apart and it looked a little sparse but filled in a lot the first year. This year, the 2nd year, the original plants are twice and a few three times their original size so I'm glad we allowed 2 feet. I planted Balsam (annual) all around and in the middle I have a Yucca plant and 4 Echinacea. I've posted pics below to show the dramatic change in plant sizes in just 2 seasons:
16 Jun 2014
25 July 2014
14 July 2015
18 July 2015
Best of luck with your garden. We love ours.
16 Jun 2014
25 July 2014
14 July 2015
18 July 2015
