The Shamrock Plant

by Judy Feldstein

 

Shamrock Plants, or Oxalis, appear in flower shops around St. Patrick’s Day. These plants have the nickname Shamrock because of their soft, thin, triangular leaves that are divided into three leaflets just like a lucky clover. Oxalis regnelli, the green leafed version, has small delicate white flowers while Oxalis triangularis, or False Shamrock, has dark purple leaves and pinkish lavender flowers. Shamrocks are bulb plants and die back after they bloom; but don’t throw them out, they just need a little rest before starting to grow again.

 

Care Instructions

 

Light

 

Shamrocks need bright indirect light from an east or west-facing window.

 

Water

 

Keep the soil of a Shamrock barely moist but never soggy; allow the top 2” of soil to dry out before watering. It’s best to water a shamrock from the bottom so that the thin fragile stems of the plant don’t get water logged and the soil stays loose.

 

Fertilizer

 

Feed a Shamrock monthly in the spring and summer when it is actively growing with a basic houseplant food at ½ the recommended strength. Never feed a Shamrock when it is dormant and the bulbs are resting.

 

Temperature

 

Shamrocks like cool temperatures and do best in 60-70 degrees during the day and 55-65 degrees at night.

 

Humidity

 

Basic house hold humidity is fine for this plant.

 

Soil

 

The soil should be loose and sandy rather than rich and organic.

 

Flowers

 

Oxalis regnelli has small delicate white flowers. Oxalis triangularis has delicate little purple flowers.

 

Pests

 

Shamrock plants attract aphids, whiteflies, and spiders mites. Use the “green solution,” a mixture of ½ mild soapy water, ½ alcohol and a few tablespoons of mineral oil to get rid of the spider mites and aphids. Yellow Sticky Insect Cards is the best way to handle the whiteflies.

 

Propagation

 

Shamrocks are propagated by bulb division, or in a Shamrock’s case, bulblet division. The bulbs of this plant are small, white, and puffy.

 

Toxicity

 

Shamrocks have a mild toxicity if eaten in very large quantities.

 

Resting

 

After a Shamrock blooms the leaves turn yellow, droop and eventually fall off. This usually occurs in the late fall and while the plant appears to be dying, it is really going into a resting or dormant phase. After all of the leaves have died, stop watering and move your Shamrock to a cool area with low light. Green Shamrocks need to rest for 2-3 months while Purple Shamrocks need to rest for about one month. After the plant has rested for the appropriate amount of time, move it back to bright indirect light and water as usual. Once new growth appears, fertilize with a basic houseplant food at ½ the recommended strength. Shamrocks may go dormant several times a year.

 

Frequently Asked Questions

 

1. My Shamrock is tall and spindly looking. Can I ever get it to look full again?

 

Move your Shamrock plant to a location that gets more light, but be sure the temperature stays on the cool side.

 

2. I have lots of leaves on my Shamrock plant but I never get any flowers.

 

The soil that your Shamrock is planted in is probably too rich in organic matter and not sandy enough. Rich soil helps with leaf growth but impairs flower growth.

 

3. When is the best time of year to propagate a Shamrock?

 

The best time to propagate a Shamrock is right after its dormant stage when you are about to return it to its normal bright location and start watering again. Separate the bulbs and plant them in slightly sandy soil.

 

4. My Shamrock always gets yellow leaves not just when it’s going dormant. What am I doing wrong?

 

Try allowing the soil of your Shamrock get a little dryer before you water; you are probably keeping the soil too moist.

 

Judy Feldstein can be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it.

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