How to Grow: Oxalis

Listen to this podcast on how to grow oxalis as a houseplant and outdoors.

Purple Flowers, Oxalia, White FlowersDepending on who you talk to oxalis or the shamrock plant is an invasive weed, a sour tasting groundcover or a cute houseplant. All three are right. In warm climates oxalis can be an attractive groundcover or a weed. In colder climates yellow sorrel is an oxalis that grows as an understory plant in the forest. And then there’s the tender houseplant versions. This is where oxalis becomes more interesting.

Oxalis may be called the shamrock plant, but it’s not related to true shamrocks. True shamrocks are in the Trifolium or clover family.

Oxalis has a number of colorful new varieties on the market. The Proven Winners Charmed Series features ‘Wine’ with purple leaves and white flowers, ‘Molten Lava’ with chartreuse foliage and yellow flowers and ‘Zinfandel’ with wine red leaves and yellow flowers. ‘Iron Cross’ is also a popular green leafed variety with a burgundy cross in the center and pink flowers.

These colorful oxalis make great annuals in a container, rock garden or flower border. You’ll also see lots of them as houseplants in garden centers. But you have to be smart about growing them indoors.

Many try growing oxalis as houseplants and end up tossing them because they look ratty. The key to success with oxalis is to be merciless. Oxalis needs a dormant period in late fall and early winter. Before bringing your oxalis in for winter, cut them back to the soil line, stop watering and store them in a dark, cool room for a few months. Bring them out in late winter and they will grow better with the longer, warmer days. Oxalis also can become insect infested indoors. Cut them back if that occurs and repot them. They will regrow from their tiny bulbs. Oh and oxalis leaves can be poisonous to pets if eaten in large quantities.

Excerpted from the Vermont Garden Journal on Vermont Public Radio.