Trim These Perennials in September for Healthier Growth & Bigger Blooms Next Spring
1 Peonies Zones 38
Cut foliage to ground level.
Dispose of leaves to prevent fungal disease.
Stems: cut 12 in. 2.55 cm above soil.
2 Hostas Zones 39
Wait until leaves turn mushy after frost.
Cut foliage to 2 in. 5 cm from crown.
3 Daylilies Zones 39
Trim spent foliage to 46 in. 1015 cm.
Remove dead leaves for tidier beds.
4 Bee Balm Zones 49
Cut stems to 4 in. 10 cm.
Dispose of trimmings prevents mildew.
5 Tall Garden Phlox Zones 48
Cut stems to 23 in. 58 cm.
Remove diseased foliage.
6 Bearded Iris Zones 310
Trim to 6 in. 15 cm.
Cut leaves into a fan shape.
7 Lavender Zones 59
Light trim only. Remove faded flower stems.
Leave 23 in. 58 cm green growth.
8 Yarrow Zones 39
Cut stems to 23 in. 58 cm.
Remove flower stalks after bloom.
9 Black-Eyed Susan Zones 39
Option 1: Cut to 34 in. 810 cm.
Option 2: Leave seed heads for birds.
10 Spike Speedwell Zones 38
Cut back to basal foliage low rosette.
Leave 12 in. 2.55 cm.
11 Globe Thistle Zones 38
Cut stems to 23 in. 58 cm.
Remove seed heads to prevent spreading.
When to Cut By USDA Zone
Zones 35: After first frost late SeptOct.
Zones 67: Mid to late fall, before collapse.
Zones 89: Slightly earlier; focus on tidying & disease prevention.
Hi there — I’m Ava, the creator behind Ava Garden Tips 🌿
I’ve always been passionate about plants, flowers, and the simple joy that comes from growing something beautiful. What started as a small balcony garden has turned into a love for helping others create their own green spaces — no matter how big or small.