How to Prune Rosemary: After Bloom, Never Into Bare Wood

Prune rosemary after it flowers, take no more than about 20 percent of the growth at a time, and never cut into thick woody stems that have no needles. Penn State says to prune after flowering, and Wisconsin says not to remove more than 20 percent at once. Arizona explains the limit on old wood: thicker stems without needles do not initiate new shoots behind the cut. This guide sits under our rosemary shrub care guide.

When to prune

The Arizona advice is written for low and mid-elevation deserts. Penn State and Arizona agree on the common thread: wait until the flowers are done rather than cut before bloom.

How much to remove

Wisconsin says not to remove more than 20 percent of the growth at a time. NC State goes further for a plant that has finished flowering: it says severe pruning once the bloom has passed is an option to encourage dense foliage, and it lists heavy pruning among the things rosemary tolerates. Wisconsin’s figure is a per-pruning limit and NC State’s is a post-bloom option. The sources do not reconcile them, so on an established plant with plenty of needles the 20 percent limit is the more conservative reading.

The woody-stem limit

Arizona’s rule is the one that catches people. Thicker stems of older rosemary shrubs without needles should not be cut, because they do not initiate new shoots behind the cut. Make cuts where the stem still carries needles.

1. Wait until the flowers fade. Penn State says prune after flowering.
2. Cut where there are still needles. Arizona says bare thick stems do not sprout behind the cut.
3. Stay near 20 percent. Wisconsin’s limit for one pruning.
4. Use sharp pruners, and loppers for thicker stems. Arizona’s tool advice.

Shaping young and upright plants

Wisconsin says small plants can be shaped by frequent tip pinching, and that older plants can be pruned lightly to the size you want. UMD Extension also says to pinch seedlings and young plants to direct growth. For upright rosemary, Arizona says to prune selectively rather than shear.

Pruning as harvest

UC IPM says to trim sprigs of up to 4 inches from the longest growing branch tips. UC IPM treats this as the regular trimming that encourages new growth, so harvesting and pruning are the same job.

Keeping it to size

Penn State gives rosemary’s size as 2 to 6 feet tall and wide, and UMD Extension gives 36 to 72 inches tall. NC State says rosemary tolerates drought, partial shade, salt, heavy pruning and most soil types except clay. For a plant that is outgrowing its spot, the choice is between the Wisconsin 20 percent trim, repeated over time, and the NC State post-bloom cut.

Mistakes to avoid

For hardiness zones, containers and winter protection, see our rosemary shrub care guide.