THERE is nothing like the threat of a killing frost to get a gardener hopping. Although my potted plants were brought indoors long ago, I had neglected — at least until I heard tonight’s forecast — to lift my cherished lemon verbena, parsley, petunias and geraniums (like ‘Apple Blossom Rosebud’, above), from their vulnerable positions in the open garden. Read on, if you’re not too squeamish, and I’ll show you my surgical procedure that permits the successful overwintering of these tender herbs and annuals.
If there is one thing plants can’t stand, it’s to have someone meddle with their roots. But when you need to pot an herb like parsley that has been growing in the open garden, or a petunia that has prospered for months in a 12-inch hanging basket, root-manipulation is unavoidable. The goal is to get these monstrous growers into pots that are small enough to fit in a window, or on a shelf beneath fluorescent lights. And to do this, roots must be trimmed off, and usually rather severely.
After digging up or “lifting” a plant, I cut away one half- to two-thirds of its root system — enough of the roots, in fact, to enable potting into a 4- or 5-inch pot. Then I remove most of the top growth to accommodate the reduction of roots.
Parsley (above), requires additional cutting, because it grows not from a stem, but from a crown. I cut rooted sections of the crown with a sharp knife, which always results in a number of new, house-sized plants. Even after this traumatic surgery, recovery for parsley is quick. Under good light and cool temperatures, new growth emerges in about one week (below).
With zonal geraniums (above), it is my policy to reduce the foliage to three pieces of three inch growth. Even with good light and cool temperatures (60 degrees is better than 70), these plants suffer such a shock from the root-cutting ordeal that they rarely bloom again before May. If you want geraniums to bloom in winter, the best plan is to grow new plants from stem cuttings taken in May or June.
Petunias (above) are cut back to within three inches of their lives (I trim the roots, too, in order to fit the plant in a 5-inch pot). In my fluorescent light garden, new growth resumes with lightning speed (below). I feed petunias regularly with a high-phosphorous formula (1/4 teaspoonful to a gallon of room-temperature water), and they bloom from December on.
You can propagate petunias from stem cuttings, too. Just follow these simple directions.
Lemon Verbena can be overwintered exactly like a geranium, except it demands extra humidity after potting. A clear plastic bag set over the plant for two weeks helps it to adjust to house life.
WARNING! Once you have lifted, cut, and potted a number of non-hardy plants, you will feel like a professional horticulturist. You will also feel like a hero, because you’ve saved your cherished garden herb or beloved flowering annual from the fatal fingers of frost.
If you have any questions about overwintering your plants, please post them in the comments section below. I’m all ears!
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