Tuesday, March 12, 2013


Shamrocks are symbols of St. Patrick’s Day as legend has it that St. Patrick picked a hop clover with its three-lobed leaf to illustrate the holy Trinity. Shamrocks are associated with the country of Ireland, friendship, Christianity and good luck. What kind of plant is a shamrock? As Master Gardeners know, a common name can refer to several different plants and there are different plants that are called shamrocks; the defining feature on these plants is lobed leaves.

The official shamrock of Ireland is Trifolium dubium (try-FOL-lee-um   DOO-bee-um), a clover with yellow flowers and lobed leaves. The word Shamrock comes from the old Irish word "seamrog"
which means "summer plant."

Trifolium dubium
Since clover is very difficult to grow indoors, garden centers, florists and grocery stores sell varities of Oxalis, some with green leaves and others with burgundy leaves. They are not native to the United States.

Oxalis triangularis burgundy
The Oxalis acetosella (ox-AL-liss   ass-eh-TOW-sell-ah) plant, a member of the wood sorrel family, is grown from a bulb, has small dark green lobed leaves and grows about 6"high. It grows as a short mound in the pot with shoots sprouting upward and has small, white cup-like flowers with veins.

They prefer bright light but not direct sun and a consistently moist soil, not soggy. Don’t overwater. If the foliage turns yellow, this could be a sign of overwatering.

Oxalis acetosella
This plant needs to go into a dormant state two or three times a year. When the plant loses its vigor, stop watering and pull off the leaves as they turn brown. Put the pot in a cool, dry place for two or three months. To break the dormancy, resume watering and add a house plant fertilizer (10-10-10). The plant should start to revive and thrive for a few more months.

Another variety, Oxalis regnellii (ox-AL-liss   reg-NEE-lee-eye), is also sold as a shamrock. This plant is similar to the O. acetosella but has white star-like flowers. Care for this plant is the same.

Oxalis regnellii

Learn more about shamrocks
USDA Plant Database-  Oxalis
USDA Plant Database - Trifolium dubium
University of Arkansas-Shamrocks
University of Arkansas Plant of the Week- Shamrock
University of Vermont Extension – Shamrocks for St. Patrick’s Day
Philadelphia County Master Gardeners Shamrocks and Fake Four-Leaf Clovers

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