By Bev Johnson

Master Gardener

On St. Patrick’s day, everyone wants to claim a bit of Irish. Every store seems to have pots of shamrocks. The only thing is, they aren’t the true Irish clovers. They’re oxalis. Oxalis are found on every continent but Antarctica. Most of those for sale come from South America and the coastal region of South Africa. These wood sorrel, or oxalis can come in a wide range of appearance. 

Leaves can be green to purple, hairy or smooth and even marked with dots or stripes. One or more flowers are borne on stems and can be white, pink, red, purple or even yellow. They make good house plants. At least one of these color combinations should go with your décor.

The South American types have underground bulbs, the South American types have rhizomes. Both should be potted in a clay pot so if yours is in a plastic one, and you plan to keep it, replant in a clay one. To make a nice full pot, put 3-5 plants in a 4-inch pot. These pots work best because they will provide good drainage and allow air to reach the roots. Use a soilless mix as they drain well. You don’t want to rot the bulb or rhizome.

In the greenhouse, the plants are forced to bloom. The temperatures are kept between 55 and 60. As roots start to grow and shoots emerge, the temps are increased to the mid 60’s. The purple shamrock takes a bit of a different route. They are forced at 70 degrees. When they show signs of growth, the temps are dropped to the mid 60’s.

Put your shamrock in bright light and feed it regularly to keep it blooming well. They like cooler temperatures best.

Eventually the leaves will wither, turn yellow and fall off. All is not lost. The plant is just resting. Slow down on watering and eventually stop watering altogether. Now you can dig the bulbs or rhizomes out and repot. Or, if the pot isn’t too crowded, let it rest in a very cool area, 55 to 60. 

Keep watering to a minimum until you see signs of life then increase watering and begin to fertilize again. They like a summer vacation along with your other house plants.

Oxalis are a “dancing” plant. Some of them exhibit nastic movement. This word comes from the Greek word nastos meaning “close pressed.” The plant is moving every day. Both leaves and flowers in some varieties open up during the day and close at night. This is called photonasty. Some species will open when the temperatures are warm and close as the day gets cooler; thermonasty. These movements help the plant conserve water and maximize photosynthesis. Many of them come from harsh environments so this is how they adapt.

Check every new plant that comes into your house for bugs. Look for webs of spider mites, the white cotton of mealy bugs, or any activity on the soil, fugus gnats. 

If one of the plants in a group is infested, all of them probably are. Leave them in the store. These critters are not fussy about housing. They will be happy in your house and on your plants. It is much easier to prevent an infestation then attempting to cure it.

On St. Paddy’s Day, have your Guinness, wear green and get a shamrock even if you’re not Irish. We enjoy the company.