Marin IJ Articles
August 26, 2017
I have a lovely pink and white ‘Martha Washington’ geranium — actually a pelargonium, botanically speaking — that has been blooming outside my kitchen door for many years. I’ve named her Trudy and she thrives in bright sunlight and blooms practically year-round in my Mill Valley garden.
Both geraniums and pelargoniums are members of the Geraniaceae family and name confusion dates back decades. True geraniums are also commonly known as cranesbills.
One day in May I realized Trudy was looking rather leggy with long bare woody stems supporting flowers and foliage at the stem ends. While the blooms were still lovely, the plant was on its way to becoming an eyesore. Clearly, help was needed!
Pelargoniums are identified as woody-based perennials and many are easily rooted. I took multiple cuttings to insure Trudy’s progeny would live on. After much hacking, I left the root ball with a few woody limbs attached destined for the compost. A week or so went by as this dry lump just sat there. Imagine my surprise when I noticed tiny leaves emerging from the soil and from every lifeless appearing limb! I have since replanted this tough gal in a container filled with fresh potting soil and am amazed to watch her regeneration.
Lesson learned: don’t be afraid to prune pelargoniums. I thought I was doing my job by deadheading spent blooms, but removing the flower stem at its base is really necessary. Pinch back growing tips of young plants to force side growth. Keep pinching back to encourage a full, shapely plant. Don’t be afraid to dramatically prune older, scraggly growth to rescue overgrown specimens.
Late fall is an ideal time to cut back pelargoniums by 1/3 to 1/2 if you live in a relatively frost-free area or will be overwintering your plant in a sheltered location. If you live in an area with frost, where your pelargoniums regularly go dormant during the winter, wait until early spring to do major pruning.
Allow pelargoniums to dry between waterings. Due to years of drought, I was in the habit of emptying half-filled water glasses into the containers around my kitchen door. Regular overwatering encouraged leggy growth. Witnessing the rebirth of Trudy in the bone-dry root ball helped me realize the value of letting the plant drain thoroughly.
While Trudy is rejuvenating in the back garden, I installed a lush hot-pink pelargonium by the kitchen door and suddenly its blooms ceased. Upon close examination, I discovered it is host to tobacco budworms! These caterpillars can be tricky to spot, as their colors and markings can vary considerably. Signs of infestation include buds riddled with holes where the larvae have entered to eat the petals lack of blooms opening, and a trail of dark specks of frass (feces) on the plant. Once the buds are devoured, these hungry larvae begin eating the foliage. The small, light brown budworm moths emerge from overwintering pupae in spring and lay their eggs primarily on pelargoniums, petunias, nicotiana and snapdragons.
Control budworms by handpicking caterpillars and dropping them in a pail of water with a bit of liquid dish soap. Consider spraying with bacillus thuringiensis, or BT, as it commonly known — a naturally occurring bacteria that kills worms and caterpillar-stage insects, but has no effect on birds, earthworms or beneficial insects like honeybees and ladybugs when used as directed. BT comes in liquid form and is available at most garden supply stores. Spinosad products are sometimes recommended for budworm control, but can be more harmful to beneficial insects and should not be used as the first line of defense.
Regular pinching and pruning, as well as monitoring for pest infestations, will keep your pelargoniums shapely and blooming for many, many months.