Tips for growing and interesting facts about shamrocks
by Jo Ellen Meyers Sharp
The shamrock is one of the defining symbols of St. Patrick's Day, but what we call the shamrock isn't the same as the Emerald Isle's.
In the United States, we use oxalis as a shamrock. In Ireland, the shamrock is a yellow-flowered clover or trefoil (Trifolium dubium). The clover is hard to grow indoors, so American nurseries and florists sell the easy-to-grow Oxalis plants instead.
The shamrock became associated with the patron saint of Ireland after he allegedly plucked one from the ground to demonstrate the Holy Trinity of the Roman Catholic faith: the Father, Son and Holy Ghost. Besides good luck, the shamrock symbolizes rebirth, which is really what spring is all about.
The shamrock most readily available this time of year in the Midwest is Oxalis acetosella, which has green, triangular leaves and white flowers.
This frost-tender bulb has beautiful cousins that provide flowers and colorful foliage from spring until fall in pots or as summer annuals in the ground. However, these ornamental oxalis should not be confused with wood sorrel (O. stricta), an invasive species from Asia and Europe, which is the bane of many gardeners.
The morning sun combined with part shade is best for ornamental oxalis. They prefer well-drained soil and do best when kept evenly moist, but not wet.
Oxalis falls flat when the soil dries out but usually perks up with a good drink. Apply a water soluble, all-purpose fertilizer according to label directions for tender bulbs, potted plants or summer annuals.
Because oxalis is tender throughout the Midwest, I grow mine in pots, which I move to an unheated basement every fall. You can also dig the bulbs, rinse off the soil, dry them and store in mesh bags in a cool, dry place.
I don't water the pots during the winter, which allows the tubers to go dormant. About this time of year, I move the containers upstairs to a bright window, water them and add a little liquid fertilizer. Every few years, I divide the tubers in spring and share them with friends or plant them in another container.
I move the pots outdoors for the season when all danger of frost has passed. At night, oxalis leaves fold and collapse against their stems. When day breaks, the leaves open wide again.
Garden centers carry oxalis already growing in nursery pots or as bare bulbs ready for planting. The widest selection, however, will be found through online and mail-order retailers.
Sometimes known as the Hoosier Gardener, Jo Ellen Meyers Sharp lives in Indianapolis and is part owner and editor of Indiana Living Green magazine. Her work has also appeared in many other publications, including The American Gardener, Garden Gate and Greenhouse Grower. Meyers Sharp also speaks about gardening and sustainable living throughout the Midwest and is a director of the Garden Writers Association.