I Killed 3 Before Anyone Told Me - Stop Cutting Back These 9 Perennials in Fall, by Urban farming on YouTube. 21 min 57 s.
- Video length
- 21 min 57 s
- Time to do it
- 20 minutes
- Difficulty
- Easy
- Steps
- 9
What you need
Steps
Make a list of your perennials before you tidy up. Mark the ones you plan to leave standing: purple coneflower, black-eyed Susan, Joe-Pye weed, garden mums, coral bells, agastache, ornamental grasses, hellebores and lavender.
Leave the stems and seed heads on purple coneflower, black-eyed Susan and Joe-Pye weed through winter. The hollow stems shelter native bees, and birds eat the seeds.
Do not cut garden mums to the ground after they flower. Leave the stems and any basal leaves to protect the crown, then cut back in spring once new growth appears.
Keep the evergreen leaves on coral bells and hellebores. Remove only damaged or diseased leaves, and clear fallen leaves that smother the crown.
Leave ornamental grasses and agastache standing. Cut grasses back in late winter or early spring before new shoots appear, and cut agastache once you see fresh growth at the base.
Prune lavender in spring, not fall. Wait until new growth shows, then trim lightly into the green stems and never into the bare woody base.
Stop frost heave by leaving stubble and adding a light mulch around crowns, not over them. This keeps soil temperature steady through freeze and thaw swings.
In fall, do cut back peonies, bee balm, garden phlox, hostas and bearded iris. Bag and bin any diseased leaves instead of adding them to compost.
Make a spring cleanup plan. Check each plant for new basal growth, then cut old stems to about 2 to 4 inches above the crown.
Tips and common mistakes
Never cut lavender into old bare wood, because it rarely regrows from there.
Leave stems 8 to 12 inches tall on bee-friendly perennials so pollinators have somewhere to nest.
Pull mulch back from direct contact with crowns to avoid winter rot.
Do not compost diseased foliage from phlox or bee balm, since spores can survive.
Questions
Why can cutting back perennials in fall kill them?
Removing stems and leaves exposes the crown to frost heave, freeze and thaw swings, and rot. The plant loses its winter protection and may not survive to spring.
When is it safe to cut back perennials in spring?
Wait until you see new green growth at the base, usually in early to mid spring. Then cut the old stems to a few inches above the crown.
Which perennials should I cut back in fall?
Peonies, bee balm, garden phlox, hostas and bearded iris can be cut in fall. Bin any diseased leaves rather than composting them.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
