When fall arrives, the garden abounds with tasks and to-dos to accomplish before winter. One important thing to add to your list is cutting back your perennials, which protects them from pests and diseases during winter. But keep in mind that not all plants should be pruned in fall, as pruning at the wrong time can prevent your plants from blooming next season. To help you get this gardening task right, we spoke to experts who shared which plants you should always prune in fall.
Phlox
Phlox (Phlox paniculata) is a beautiful flower, but when summer is over you’ll want to do some work on the leftover foliage. “Summer blooming garden phlox is susceptible to mildew, and even the mildew-resistant varieties may be affected if there is a lot of wet weather,” says landscape designer and author Jan Johnsen. If your phlox has powdery mildew, you should cut back and destroy all foliage and stems in the fall. If there isn’t a mildew problem, cut back the stems in late autumn.
- Zones: 3 to 8
- Size: 24 to 48 inches tall x 24 to 36 inches wide
- Care requirements: Full to partial sun; moist soil
Hostas
Members of the hosta (Hosta spp.) family are beloved for their fantastic ornamental leaves. The vibrant foliage makes the plant a great addition to the garden even when it’s not blooming. But as lovely as hosta foliage is, it just doesn’t stand up well to autumn weather. “Cut back your hostas in late fall,” says Johnsen. “Hosta leaves turn yellow and after the first frost, the leaves tend to become soft and mushy.” Cutting off the dead leaves prevents disease, insects, and slugs from hiding in the foliage during winter.
- Zones: 3 to 9
- Size: 1 to 2 feet tall x 2 to 3 feet wide
- Care requirements: Shade; moist, rich soil
Chives
Chives (Allium schoenoprasum) produce purple spherical blossoms that bring a delightful cheer to the spring garden and attract pollinators. Cut your chive plants back during the growing season to encourage a fresh round of growth and to give them a healthy start next spring.
- Zones: 3 to 9
- Size: 12 to 18 inches tall x 12 to 18 inches wide
- Care requirements: Full sun; rich, well-drained soil
Daylily
Daylily (Hemerocallis) is one of the first perennials to begin shooting up buds in spring, filling the landscape with attractive foliage and impressive blossoms. Daylilies look much better if you remove all the spent leaves when the growing season is over—doing so also clears the way for fresh buds to arrive next year. “During summer, daylily leaves support the beautiful flowers, but in the fall, the leaves start to look ratty,” says Johnsen. “These dying leaves may harbor harmful slugs and more.” For this reason, and to promote tidiness, give daylilies an autumn trim.
- Zones: 3 to 9
- Size: 24 to 48 inches tall x 24 to 36 inches wide
- Care requirements: Full to partial sun; well-drained soil
Yarrow
Charming as yarrow’s (Achillea millefolium) blossoms and unique leaves can be, they become crumpled and brown once winter weather arrives. To prevent this, trim back your yarrow plants in the fall so that your garden doesn’t look weedy—just take some care not to trim them all the way to ground level.
- Zones: 3 to 9
- Size: 2 to 3 feet tall x 8 to 12 inches wide
- Care requirements: Full sun; well-drained soil
Bee Balm
To attract pollinators and create a stunning flower display in your garden, you can’t miss with bee balm (Monarda didyma). Hummingbirds in particular think it is fantastic. However, when the days grow short, and the first frosts take down bee balm’s foliage, cut back all of the spent plant material to prevent it from becoming a breeding ground for powdery mildew.
- Zones: 3 to 9
- Size: 36 inches tall x 8 inches wide
- Care requirements: Full sun; well-drained soil
Chrysanthemum
Mums (Chrysanthemum), with all their beautiful colors, are always a garden favorite come fall. But once the flowers are spent, cut back this plant to encourage growth next season. When pruning, leave about 1 to 2 inches of stem to help protect the roots from the cold.
- Zones: 5 to 9 when grown as a perennials
- Size: 2 feet tall x 2 feet wide
- Care requirements: Full sun; well-drained soil
Iris
The large blossom of an iris (Irish spp.) is a sight to behold in the garden. Leave the leaves for as long as possible to help the plant produce late-season energy, but once the foliage is limp and brown, cut back everything except for a little bit at ground level.
- Zones: 3 to 9
- Size: Varies; 12 to 36 inches tall x 24 inches wide
- Care requirements: Full sun; well-drained soil
Delphinium
Delphinium (Delphinium spp.) plants are great for adding vertical height to your garden, but make sure to cut them back in the fall. Do so by removing most of the foliage after the first major frost, but leave a few inches near ground level for insulation.
- Zones: 3 to 7
- Size: 4 to 6 feet tall x about 18 inches wide
- Care requirements: Full sun; rich, moist soil
Goldenrod
Goldenrod (Solidago) can spread aggressively and is considered a weed by some, but other gardeners appreciate its delicate golden blossoms. That said, goldenrod loses its beauty once it has been hit by frost, so plan on trimming the plant back in fall—it will happily pop back up next year.
- Zones: 2 to 8
- Size: 2 to 3 feet tall x 8 to 12 inches wide
- Care requirements: Full sun; well-drained soil
Blanket Flowers
Reminiscent of large, vibrant daisies, blanket flower (Gaillardia aristata) adds a lovely warmth to the garden landscape. When the season ends, trim this plant right to the ground. But note that you can also leave blanket flower intact if you enjoy the look of the dried flower stems.
- Zones: 3 to 10
- Size: 24 inches tall x 24 inches wide
- Care requirements: Full sun; well-drained soil
Balloon Flowers
Balloon flower (Platycodon grandiflorus) boasts bright, concave bell-like blossoms that fill the garden with color and whimsy. You can cut them back to ground level in fall when they’re done blooming.
- Zones: 3 to 9
- Size: About 24 inches tall x 24 inches wide
- Care requirements: Full sun; well-drained soil