How to Prune Rosemary

Among garden plants, rosemary is an all-around powerhouse. Packed with antioxidants, it’s an essential herb for flavoring meats, vegetables, bread and even cocktails. It’s perennial, hearty and drought-resistant. Its flowers attract bees and hummingbirds, and its pleasant aroma repels mosquitoes. What’s not to love about this pretty, aromatic herbal plant?

If you keep rosemary in your garden or as a potted plant on the patio, it may grow so well that you occasionally need to prune it. Here’s what you need to know about pruning rosemary to keep this hard-working plant healthy.

When to Prune Rosemary

Rosemary does well in USDA Plant Hardiness Zones 7 to 10, and may survive winters in Zones 5 and 6 if adequately protected.

Determining when to prune your rosemary depends on the annual weather patterns where you live. You can safely prune anytime from spring to late summer. Just make sure the risk of late spring frost has passed and that you prune at least four to six weeks before the risk of fall/winter frost.

If the plant is indoors you’ll obviously have fewer worries about frost. But spring or summer is still the best time to snip.

How to Prune Rosemary

The good news about rosemary is that it doesn’t actually need to be pruned to thrive. Pretty Purple Door home gardening and landscape design blogger Amy Fedele says there are two main reasons gardeners prune rosemary. “One is to create a bushier plant and the other is to reduce its size,” she says.

Fedele offers the following tips on how to prune your rosemary plants:

• Start with a sharp, clean pair of pruning shears or garden scissors. Sterilize your pruning shears by wiping the blades with rubbing alcohol or bleach, then rinse the shears and dry them off with a clean cloth. “You should do this when pruning any plants,” she says, “but especially herbs or edibles.”
• Remove any dead or faded flowers.
• Prune off any broken or diseased branches whenever you see them.
• “To create a bushier rosemary plant,” says Fedele, “simply cut off one to two inches of the branches along the outside of the plant. This will force the branch to split and it will fill out the plant.”
• When pruning to reduce the size of your rosemary, Fedele says you can cut the entire plant back by one-third any time during the growing season. To significantly reduce the plant’s size, she says it’s better to cut it back over a series of prunings, ideally spaced every three months.

Propagation & Winterization

Fedele adds it’s easy to propagate your rosemary. “Take some of the tips you pruned and strip off the needles from the bottom half of the cutting,” she says. “Dip them in rooting powder and plant them in the ground.”

If you are in a freeze zone, try to winterize your rosemary. One option is to bury it under a layer or mulch loosely or compost. The other is to cover it with a frost blanket or surround it with rock or cinder block walls, which will absorb and give off heat. If you potted rosemary outdoors, bring the plants into a bright room of the house, such as an enclosed porch or sun room.

Fun rosemary fact: Did you know that rosemary flowers are edible? Fedele suggests tossing a few fresh blooms onto a salad. “The flower has an even more intense taste than the leaves, and is said to improve memory!” she says.