Question: I love that shamrock-looking plant that is sold around Saint Patrick's Day. Unfortunately they die every year. How can I keep them healthy for more than a year?
Answer: The familiar St. Patrick's Day plant that is sold in grocery stores and florists is Oxalis acetosella, one of the many members of plants in the oxalis family. The true Irish Shamrock plant, (Trifolium dubium), is a type of clover, and is difficult to grow indoors. The oxalis plant is easy to grow and when cared for properly can be a longtime addition to your home.
Oxalis leaves are very distinctive. They can be purple or green and have three rounded- or triangular-shaped leaves at the tip of a delicate stem. Most oxalis exhibit nyctinstic movements, meaning they fold up their leaves at night, hugging their stems, and then reawaken with the rising sun.
When you think of shamrocks you may visualize the cool air and moist environment of Ireland. These are the conditions that your plant requires when actively growing. Bright light and moist soil will encourage strong blooms and lush growth. Oxalis will bloom all winter if placed in a bright sunny window. Fertilize only when it is actively growing.
Temperatures should be between 50 to 65 degrees at night, and no greater than 75 degrees during the day. In the summer, when temperatures are above 75 degrees, your plant will begin to go dormant.
The first sign of dormancy is when the leaves begin to look sick and eventually die. During dormancy, stop watering. Let the leaves die naturally and then remove them. Place the plant in a cool dark place for about three months.
New green shoots will signal that the plant is waking up and needs to be moved back into the light. If your plant begins to get lanky it is telling you that more sunlight is needed. If your plant has not bloomed in a while it may need a rest and should be allowed to go dormant.
To divide your shamrock, wait until the bulbs reach the end of the dormant cycle. Then take them out of the pot, remove the small side bulbs and replace them in a new pot, just below the surface level, in a mix of potting soil and sand.
Keep the surface just moist to the touch until the plants become established.
Next St. Patrick's Day you will be able to spread the luck of the Irish with your gift of a shamrock plant.
Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Exten-sion, 6260 Old Harding Highway, Mays Landing, NJ 08330. Email: