Shamrocks shine for St. Patrick’s Day
Clover plants (Trifolium spp.) may have been the first “shamrock” connected with St. Patrick, the patron saint of Ireland. When teaching Christianity to the Irish, St. Patrick illustrated the Holy Trinity using the clover’s three-leaf structure. To recognize St. Patrick’s association with clover, the oxalis (Oxalis triangularis), commonly known as false shamrock, has become a popular houseplant to purchase at the beginning of March, just in time to celebrate St Patrick’s Day on Sunday, March 17.
A member of the wood sorrel family (Oxalidae), oxalis is an easy-to-grow indoor or outdoor plant with over 500 species that are native to Africa and South America. Two native wood sorrels can be found in Butler County: the violet wood sorrel (O. violacea) and the common yellow wood sorrel (O. stricta). Look for the violet wood sorrel in wooded areas. Common yellow wood sorrel often is found in disturbed areas and can be an aggressive weed in landscapes.
Growing from tubers, varieties of oxalis produce clover-shaped leaves in shades of purple, burgundy, pink, green and silvery gray color. Oxalis leaves open in bright light and close in dusk or low light, a response known as nyctinastic. Its delicate, five-petalled flowers bloom in pink and white. When mature, the plant reaches a height and width of 6 to 12 inches. Oxalis plants contain oxalic acid, which gives the leaves a sour taste. While animals would have to consume a large amount of oxalic acid to become ill, it is best to keep pets away from oxalis plants.
Purchase shamrock plants that are evenly shaped with healthy leaves, flowers, and buds. Because they are sold indoors where lighting may be inadequate, their leaves may be closed when on display. Once the plant is placed in bright light or sunshine, the leaves will open. After purchasing your shamrock plant, remove the decorative wrapping from the plant’s container and place the plant on a saucer or dish in bright, filtered light. Water to keep the soil moist; overwatering can cause the roots and tubers to rot. Fertilize with a half-strength house plant fertilizer every few weeks while the plant is blooming.
When warmer weather arrives, you can place oxalis outdoors in part sun and shade. Oxalis can also be planted directly into the garden in a location with moist and humus-rich soil. Some oxalis species prefer full sun, while others prefer shade or part shade. Refer to the plant information tag prior to transplanting into the garden. Use oxalis in containers as fillers and in rock or shade gardens where they add a hint of whimsy to the design.
Oxalis plants kept in containers can be brought indoors for the winter; however, do not transplant from the garden into the home, which may result in transferring pests indoors. Oxalis go dormant in the winter months. During the fall, once the leaves die back, place the plant in a cool, dark location, water less frequently, and wait for new leaves to emerge in the spring.
Try your luck with a shamrock plant this year and add it to your garden or container for a bit of Irish lore. To learn more about shamrocks, oxalis and four-leaf clovers, visit Penn State Extension extension.psu.edu/the-botany-behind-the-shamrock or extension.psu.edu/shamrocks-as-houseplants.
If you have questions about house plants, call the Master Gardener Garden Hotline at 724-287-4761, ext. 7, or email the Master Gardeners at butlermg@psu.edu.
Lisa Marie Bernardo and Mary Alice Koeneke are Penn State Extension Butler County Master Gardeners
