Irish Shamrocks

Happy St. Patrick's Day.  I like to tell people that St. Patrick's Day is my favorite holiday - it's fun, it's colorful, and it is no work.  And, those cute little Irish shamrocks are the plant of the holiday.  What's not to like about it?

A few weeks before March 17, we start to see Irish Shamrocks show up in the stores.  These are not actually white clover, which the "shamrocks" seen growing wild in Ireland are likely to be.  White clover doesn't grow well indoors so most of the shamrocks we can buy for St. Patty's Day are Oxalis acetosella.  They have clover shaped leaves in beautiful green, red, or burgundy and are topped with white or yellow flowers.  With proper light, temperature and water, this plant will bloom all winter.

Shamrocks prefer cool temperatures, bright light, and they are very drought tolerant.  Temperatures should be around 65 degrees at night and no warmer than 75 degrees in the daytime.  Temperatures above 75 degrees may induce dormancy in the plant, evidenced by yellowing and dropping leaves.  They prefer a bright, sunny window with a southern or western exposure.  Oxalis should be watered only when the soil is barely moist throughout and the top one inch is dry to touch.  Fertilizing should be with a balanced 10-10-10 or 20-20-20 ferilizer once a month, only when the plant is actively growing.

Oxalis acetosella

Irish shamrocks fold their leaves at night and on dreary, overcast days.  This doesn't mean there is anything wrong with the plant.  If the shamrock becomes tall and leggy, it is an indication it isn't getting enough sun or needs cooler temperatures.  If the plant wilts, it needs water.  If the leaves start to yellow, it might be getting too much water.  If it stops blooming, it probably needs a period of dormancy to rejuvenate itself.

Irish shamrocks need a dormancy period of two to three months each year.  Since it doesn't like warm temperatures, spring is a good time to allow it to go dormant.  Simply stop watering and fertilizing and allow the leaves to die back.  Place the shamrock, pot and all, in a cool, dark place over the summer months.  In late summer, take it out, begin watering, and once foliage appears, place it in a bright, sunny window.

Oxalis are virtually pest free, a bonus in any houseplant.  It is susceptible to root rot if overwatered, but otherwise is pretty carefree.  Provided the right care, an oxalis will live for many years.