St. Patrick is believed to have used a three-leaf clover to explain the complexity of the Trinity to nonbelievers in 5th century Ireland. Ever since, the shamrock has been revered by the Irish and held as a symbol of good luck.

The word shamrock is derived from the Celtic word seamróg, which means “little clover.” But it isn’t clear exactly which type of clover St. Patrick used. Perhaps it was the common white or red clover, or even black medic.

We know, however, that it wasn’t the South African native we call shamrock today; it wouldn’t have been growing in Ireland. In fact, it’s not even related to clover.

Still, if you’d like to grow your own luck this St. Patrick’s Day, you should bring home a potted Oxalis regnellii plant.

A member of the wood sorrel family, shamrock varieties are available with green, red or variegated compound leaves made of three triangular leaflets. Although grown as a shade plant outdoors in zones 7-10, shamrocks need bright, direct sunlight when kept as houseplants.

Place them near a south- or west-facing window and away from cold drafts and heat sources, such as radiators.

The plants prefer room temperature to be between 65 and 75 degrees and will languish in temperatures above 80.

They also need relatively high humidity. If the air is dry, run a humidifier nearby, mist the plant twice daily, or place it on a pebble-filled tray to which you’ve added water. As the water evaporates, it will create a humid microclimate around the plant to meet its needs.

Be careful not to overwater. When the soil is mostly – but not completely -- dry, place the plant in a sink and slowly apply water until it runs out the drainage hole in the pot’s bottom, then stop. When the water has drained completely, dump out any that has collected in the saucer and return the plant to its sunny perch.

Apply a 10-10-10 fertilizer formulated for houseplants during spring and summer, according to package directions.

Your shamrock will reward you with lovely five-petaled, white, trumpet-shaped flowers in spring.

If that’s not lucky, I don’t know what is.

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Jessica Damiano writes regular gardening columns for the AP and publishes the award-winning Weekly Dirt Newsletter. You can sign up here for weekly gardening tips and advice.

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