Can I divide and replant flowers in the summer?
Question:
I have several overgrown garden beds where the plants need to be divided and replanted elsewhere. Included are: iris, daylily, lily, evening primrose, hosta, daisies, and some form of mint. I would like to tackle this now, but the recommendations are to wait until late summer/early fall or next spring. What is your advice?
Answer:
While we do generally recommend spring or fall division for many perennials in order to minimize stress and water loss to the plant, if your circumstances prevent you from doing so and summer is your only option, summer it is! Choose a cooler, overcast day to do the work, use sharp, clean tools to make the divisions, and make sure the new planting space is prepared and that all of the newly divided plants are properly watered. They will take longer to bounce back and establish than they otherwise might have, but it’s very unlikely you will cause any lasting harm to nice, healthy plants.
For reference, please check out this page from the UNH Cooperative Extension on dividing perennials in summer.