Q: When I am told to pinch back an herb, exactly what does this mean? How many inches of stem should I take as I pinch? Do I pinch off all the tips, or just one or two?
A: When you pinch back herbs, you are orchestrating two fundamental forces of plant life: the need to reproduce and the need to stay alive long enough to reproduce.
Herbs, like other plants, want nothing more than to reproduce. Most herbs want to make flowers and seeds, so they channel their energy toward stems that will grow fast and bloom quickly. With annual herbs such as basil and marjoram, bud production begins within weeks after plants are set out in the garden. Perennial herbs prepare to bloom in spring soon after days become long and warm.
Whether annual or perennial, herbs’ fast-growing tips send chemical signals down the stem telling secondary buds not to grow. In nature, sprinting to maturity is smart. What we see is a lean, upright plant with few lateral branches. It is totally intent on blooming.
Not what we had in mind! We decide that a bushier plant would be better, plus we want fresh herbs to use for making dinner. We pinch off a few growing tips, taking enough to flavor up the dish we want to make, and in the process we remove the chemical factories that have been inhibiting the growth of the little leaf buds farther down the stems. Within days, new stems pop out just below where we pinched, each one determined to produce flowers as quickly as it can.
It seems like the plant expected this to happen, which is probably true. Deer and other animals often browse on growing tips, and tender stem tips are a favorite site for aphids and other insects. Whether the growing tips are removed by deer, grasshoppers or gardeners, herbs respond to decapitation by growing into bigger, stronger plants that produce many more flowers and seeds than they would had they been left intact. For plants, our pinching is more a blessing than a tragedy.
There is no precise measurement for how long a pinched off stem tip should be. If the plant is badly in need of bulking up, I might take a few longish tips, say 4 inches long, as well as some smaller 2-inch tips. When pinching, following the plants’ natural shapes is always a wise strategy as opposed to giving them flat-tops. If a plant is holding blossoms, be sure to pinch off every last one. This will eliminate possible hormonal confusion as to where the plant stands on its reproductive mission.
Pinching is a kind thing to do to plants. Most basils are vastly improved by pinching early and often, and the same goes for scented geraniums. Thyme, mints and oreganos can be pinched more casually, by gathering stem tips as you need them in the kitchen. With rosemary and other slow-growing semi-woody herbs, pinch out stems here and there to sculpt plants.
If you plan to dry herbs, save your pinching and do it in waves, so you harvest handfuls of thyme, marjoram, oregano, or whatever in one fell swoop. This makes the drying process easy to manage, whether you dry the herbs in bunches hung in a warm, airy room, lay them out on screens or dry them in a slow oven. Depending on your climate, these herbs may produce two or more good cuttings in the course of a season. Herbs handled this way are not as pretty as those tended by hand, in pinches, but they are very productive.
Often times you literally can pinch herbs with your fingers, but this time of year I slip a small pair of scissors into my back pocket whenever I visit my herbs. Snipping off stem tips makes clean cuts, which are less traumatic to stems than twisting and pulling.
Barbara Pleasant is a contributing editor to The Herb Companion and author of several books about gardening, including The Whole Herb (see Bookshelf).