Perhaps it’s the luck of the Irish – after all, how many cultures get a religious holiday to celebrate with parades, dancing and lots of green beer (at least in America)? Heck, the Irish even get their own plant – the shamrock (Oxalis triangularis) – to help celebrate! And what a great plant it is…though it’s not from anywhere near Ireland! You’ve actually got to head far south – to South America, in fact – to find its native home.


The shamrock’s clover-like leaves and perky, white flowers make it the perfect plant for St. Patty’s Day!

Photo Credit: Gerald Klingaman

Oxalis regnellii mijke

The purple-leafed shamrock never caught on for St. Patrick’s Day, but it’s used inside as a great houseplant and outside in some beautiful flowering beds.

Photo Credit: Gerald Klingaman

So how in the world did a South American beauty find its way into this most festive of holidays, St. Patrick’s Day? Well, the plant’s lush, green, trifoliate leaves made it a shoo-in for the job. History can’t tell us whether the shamrock St. Patrick used to illustrate the concept of the Trinity was the aptly named Irish clover (Trifolium repens) or the native wood sorrel (Oxalis acetosella). Either way, neither plant had the marketing potential of Oxalis triangularis. That’s where the greenhouse industry came into the picture, when it introduced this showy shamrock into commerce in the 1930s to help the Irish (and Irish wannabes) celebrate St. Patty’s Day.

This shamrock is a tender pot-plant, growing from an underground rhizome that looks a bit like a zipper. The three-lobed, triangular, green leaves reach out on slender stems about 6 inches long. Dainty, white flowers bloom in greatest abundance in springtime, but they do appear sporadically throughout the growing season. The inch-long, five-petaled trumpets bloom in a loose terminal cluster that tends to flop about.

The shamrock is easy to grow as a houseplant. Just give it bright, indirect light and allow the soil to dry slightly before rewatering. Fertilize your plant with a typical houseplant fertilizer during the summer months and, if possible, give it a summer holiday on a shaded patio outside.

Its foliage typically dies down late in fall, which is a good time to let it dry down. But begin watering it again in January or February to force the plant into growth for the big occasion. (And be sure to watch for spider mites – the plant’s most troublesome foe.)

If you’re looking for a shamrock of a slightly different color, try Oxalis triangularis ssp. papilionacea or cultivar Charmed® Wine. This purple-leafed shamrock has the wrong-colored foliage for St. Patrick’s Day, but it’s just as lovely and often used outside as a summertime bedding plant or as part of mixed-bulb plantings. Similar in size and form to its green shamrock cousin, this wee beauty has light-purple flowers to go with its eggplant-colored foliage.

Let this festive and proud little plant prove that it doesn’t matter if you’re Irish on St. Patty’s Day. Pick up a shamrock and help spread the Irish cheer all year long! Slàinte!