garden q&a: in winter, bring oxalis bulbs inside
Q: I planted oxalis bulbs this spring. They were beautiful, but now they have been killed by cold weather. A friend says that I can overwinter them because they are bulbs. Is this true? If so, how can I do it?
A: Oxalis, also called shamrocks, are delightful plants that shouldn't be relegated to St. Patrick's Day celebrations. Though the green-leaved varieties are a common sight at grocery stores and flower shops in early March, there are many other varieties of this diverse genus that make wonderful garden specimens. Yes, there are weedy species of Oxalis (you'd readily recognize the tiny yellow flowers of some of the weedy types probably growing in your lawn), but the ornamental varieties are real show-stoppers.
One of my favorites is Oxalis regnellii “Triangularis.” It has inch-wide, three-lobed leaves in a deep, rich purple with brighter purple centers. The flowers are light pink. Another cultivar, “Silverado,” has silvery foliage with a deep green edge and white flowers, and “Iron Cross” has four-lobed green leaves that sport a dark red center. There are hundreds of others selections, each more beautiful than the next.
Because most Oxalis varieties are not hardy here in Western Pennsylvania, it is necessary to overwinter them in one of two ways. The first is to care for them as a house plant. Dig the plants up, pot them in a container and grow them on the windowsill. You'll have to cut back on the watering as the plants will have to shift into a dormant period. All the leaves will die off, and it will be a bare pot of soil for several weeks. This rest period is necessary for the plants to return a few weeks later.
The other option, the one I prefer, is to dig up the bulbs (there will be lots and lots of them) and spread them on a screen in the garage. Don't be surprised when you dig them up, though, as some varieties have bulbs that look like little sticks instead of bulbs. Let them dry for two days and then pack them into a cardboard box of slightly damp peat moss. Before packing them away, you can break the bulbs apart to separate them but this isn't a necessary step. You may find they separate themselves as you dig them out.
Come spring, the bulbs can be replanted in late April. Be sure to position them with the tiny growing point pointing up and site them in a well-drained area where they'll receive a half to full day of sun.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.
Send your gardening or landscaping questions to firstname.lastname@example.org or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.