Houseplant Help: Shamrock Plant (Oxalis spp.)

As St. Patrick's Day arrives, many celebrate by wearing green, raising a Guinness, or keeping an eye out for Irish four-leaf clover plants, also known as shamrock. Clover works well as a ground cover, but if you are thinking of a houseplant, purple shamrock plants are the better choice.

The purple shamrock plant (‌Oxalis‌ ‌triangularis‌), also called false shamrock, is the perfect stand-in for Irish clover since its dark purple leaves are composed of three to four triangular leaflets. Given this resemblance, it is no surprise that these shamrock plants appear in garden stores around St. Patrick's Day in early March. ‌Oxalis‌ houseplants are also extremely easy to care for.

‌Oxalis,‌ also known as false shamrock, is a cheery plant with triangle-shaped leaflets that look like butterflies. Purple shamrock is a gorgeous plant with dark purple — almost black! — foliage. If you really want green shamrock, ‌Oxalis‌ ‌tetraphylla‌ is a variety native to Mexico with emerald green leaves with a dark core.

‌Oxalis‌ leaflets look like butterflies ready to fly away and even flutter in the breeze. And they have more cool tricks. When the sun disappears, they fold up and close, only to open again with the coming of morning. This is a flowering plant, offering small flowers in a variety of colors, usually white, pink, or purple.

One thing I've learned from living with houseplants for decades is that low-maintenance plants are just as beautiful as prima donna plants! That's one reason ‌Oxalis‌ appeals to me. It looks exotic and sophisticated with its dark foliage but requires very little effort to keep it that way.

You can plant them outdoors in USDA hardiness zones 8 to 11 for easy-care landscaping, but it's even easier to bring them indoors as houseplants. I spend far more time admiring mine than actually doing anything to help it. Take the time to find it the right location and understand its few needs and you'll have a show-stopping plant for March holidays and beyond. The plant only needs some sun exposure, well-draining soil, and water every few weeks to thrive.

Plant placement is perhaps the most important aspect of low-maintenance houseplant care. Don't do what I did and assume that less sun is better for dark-leaf houseplants! These delicate-looking leaves can take direct sun indoors and need at least bright, indirect light. Rotate the pot now and then so that other leaves can share the wealth.

It will come as no surprise that shamrock plants require well-draining soil. The truth is that almost all of my houseplants, from pothos to corn plants to ‌Oxalis‌, need soil that lets excess water pass through readily. ‌Oxalis‌ likes some humidity but will not tolerate wet feet. That doesn't mean you have to go very far out of your way; regular potting soil will do just fine.

If the house is warm enough for you, it's likely just fine for your shamrock. ‌Oxalis‌ plants do best with temperatures between 60 and 75°F during the day, just like humans. What about nights, when household temperatures normally drop? That's fine with shamrock plants since they are fine with nighttime temperatures down to 50°F. But don't position the pot near the air conditioner or heater vent. Moderate humidity works well for purple shamrock plants.

I don't use fertilizer for my shamrock. I just add a little organic compost to the soil from time to time to increase the nutrients. On the other hand, liquid fertilizer for houseplants is fine too. Dilute it a bit more than the instructions suggest to avoid root burn.

You'll probably need to repot your shamrock houseplant every few years. Repot when it begins to seem tight in its container. Tip the root ball out of the pot and trim off any damaged or dead roots.

Pick a pot one size larger than the one the plant is currently occupying, making sure that it has appropriate drain holes. Add some potting soil to the container and settle the root ball into it so that it sits at the same level as it did in the previous pot.

The easiest way to propagate purple shamrock is by division. Wait until the plant is mature and seems to be outgrowing its container. Act during the growing season. Tip the plant out of the pot, being careful not to damage the roots. Divide the root ball into two pieces.

To safeguard the roots, the best way to do this is by hand. If the roots are extremely tangled, use garden scissors. Pot up each section of the root ball in its own container and water well.