6 Plants You Should Never Cut Back in March

A cluster of lilac flowers in bloom surrounded by green leaves — Credit:
Roksana Bashyrova / Getty Images

Pruning is essential for any thriving garden. It promotes healthier growth, maintains shape and aesthetics, and prevents the spread of diseases. But this doesn't mean you can take out your pruning shears and make a cut whenever you wish. Pruning at the wrong time has serious consequences, especially when you prune too early. Once March arrives, certain plants have already set their blooms for the upcoming flowering season, meaning pruning too early can remove those buds. And cutting back other plants can remove essential food sources for local wildlife while it's still cold outside. Ahead, a horticulturist explains which plants you should never cut back in spring, and the reasons why.

Damon Abdi, assistant professor of landscape horticulture at Louisiana State University

01 of 06

Azalea

Azaleas (Rhododendron spp.) are a popular spring-flowering perennial that dazzles in landscapes with their showy blooms in a variety of colors. If you have one of these stunners in your garden, don't reach for your pruning shears just yet. "If you prune Azaleas too early, you will remove the flower buds before they emerge," says Damon Abdi, professor of landscape horticulture at Louisiana State University. "Wait until after flowering ends to do major pruning, allowing the summer season to set new buds for the following year."

02 of 06

Bigleaf Hydrangea

Big-leaf hydrangeas (Hydrangea macrophylla) are known for their large flower heads, which emerge in late spring or early summer in shades of blue or pink, depending on the soil pH and nutrient availability. While they're one of the most popular landscape plants, gardeners need to be cautious when pruning hydrangeas, as different varieties bloom on either old or new wood. "Big leaf hydrangeas bloom on old wood, meaning that premature pruning will remove the flower buds before they have a chance to show off," Abdi explains.

03 of 06

Oakleaf Hydrangea

Similar to bigleaf hydrangeas, oakleaf hydrangeas (Hydrangea quercifolia) also bloom on old wood, meaning cutting this plant back too early will remove the floral display that's still to come, notes Abdi. Once its beautiful flowers emerge, it rewards gardeners with foliage as beautiful as its blooms, hence its namesake.

04 of 06

Ornamental Grasses

Prairie Dropseed Grass — Photographer, Basak Gurbuz Derman / GETTY IMAGES

In colder climates, it's ideal to wait to prune ornamental grasses. "Ornamental grasses provide feature foliage to the landscape, also lending a habitat to wildlife during colder temperatures," says Abdi. "In warmer climates, such as the Gulf Coast, ornamental grasses may be cut back in March to support new growth (and after the major threats of cold weather have passed). In colder climates, delaying cutting back until early to mid-April can act as insurance for the necessary insulation that wildlife may enjoy."

05 of 06

Lilac

Lilacs are a popular choice in colder climates, where they are among the first shrubs to bloom in spring, yielding clusters of fragrant flowers in shades of white, purple, pink, or pale blue. "These spring-blooming specimens will suffer if cut back prematurely, reducing the flower power that can be enjoyed as spring gets underway," Abdi warns.

06 of 06

Viburnum

Sometimes confused with hydrangeas for their impressive flower heads, viburnum (Viburnum spp.) is another spring-flowering shrub that you should never cut back in March. "Viburnums should not be pruned before they bloom for similar reasons as hydrangeas—flowers are formed on old wood," says Abdi. "Therefore, it is best to prune viburnum after spring flowers wind down."