Pruning Lavender and Rosemary
Lavender fields seem like a slice of heaven to me. Half globes of purple flowers in a regular array seem to stretch to the blue horizon. They also seem to repel mosquitoes which adds to their allure. While the sight and scent of this lavender vision certainly meet my heavenly requirements, there are other things about lavender that fall a little short of the celestial sphere. I discovered this when I spent 20 years dealing with the same garden. The first few years of my relationship with lavender were wonderful; it was only as the lavender began to age that things got rough. Instead of celestial hemispheres, my plants were turning into woody, scraggly monsters.
I used to think lavender was the perfect plant. Stick it in the ground and forget it. Boy, was I wrong…lavender needs to be pruned! At a minimum, it needs heavy pruning once a year, but a light prune when you deadhead or harvest your blossoms is a healthy addition. Heavy pruning can be done in spring or in fall depending on how cold your winters are. If winter is not very harsh, prune in the fall. Any time after August but no later than six weeks before the first frost gives the cuts time to heal.
You can use a wide variety of tools, from hand clippers to loppers, even hedge trimmers if you have a good number of lavenders to prune. The goal is to remove dead stems and flowers and excess growth, creating that lovely dome shape. One thing to remember is not to cut all the way back to the woody stems of your plant, because it will not regrow. For a hard prune, leave 1 to 3 inches above the bare woody stem. On a woody plant sometimes you get lucky, and there is new growth near the base of the plant. If that is the case, just go for it. Prune all the woody stems clear back to the new growth.
Most of the time when a lavender has gone woody, it is time to renew. Dig it out and replace it with a new plant. Unlike heaven, lavenders are not forever. A commercial lavender farm plans on replacing their plants after 6 to 10 years. The productive life span depends, of course, on the climate, soil and care that the plants receive.
It seems as if I have ignored rosemary completely, but everything I have said about pruning lavender is true of rosemary as well. Both are from the mint family and originated in a Mediterranean climate, which means they grow well in poor, well-drained soil. They are also drought resistant and tolerate heat well. They have similar growth patterns and develop an interior woody structure which can make them less attractive as they age. Lavender is grown for aromatic blooms, while rosemary is a culinary herb. Grown for its needle like leaves, rosemary is used in cooking, either fresh or dried. Both are great plants for the foothills of California.
The great thing about both lavender and rosemary is they are easily propagated from soft cuttings. Cut a 4- to 5-inch piece of new growth, dip it in growth hormone and plant four or five of them in a mixture of potting mix and vermiculite. Place your pots in a tray so you can bottom water them in a sunny window and they should root in less than six weeks. Transplant the individual plants into their own pots and, voila, you will have a ready supply of plants to use when it is time to renew your original lavenders or rosemary.
These are easy plants, well adapted to our foothill climate. Whether pruned or propagated, they are forgiving plants that help you to develop your gardening skills.
Jim Bliss is a University of California Cooperative Extension Master Gardener of Tuolumne County.
