I’ve had the same pot of Myke oxalis growing on my windowsill for almost a decade now, and over the years it’s become one of my favourite houseplants. Undemanding, with ornamental foliage and an almost continuous flowering habit, members of the Oxalis genus are always on store shelves for St. Patrick’s Day, but many make great indoor plants all year long.
The genus consists of about 850 species and contains everything from rampaging weeds to finicky rock garden plants, but the types that make the best houseplants are bulbous tender perennials native from Mexico to South America. Although not hardy enough to remain outside in cold weather, oxalis can be used as annuals in flower-beds or large mixed containers, then overwintered indoors. Hardy (to Zone 6), non-weedy wood sorrels (Oxalis articulata forma crassipes) from Japan have recently been introduced, bearing non-stop white or pink flowers.
Often marketed as shamrocks or Lucky Charm plants, Oxalis spp. are unrelated to the genuine Irish shamrock—a strain of white clover (Trifolium repens).
- Place oxalis in a bright, sunny window, and keep soil moist but not waterlogged.
- Specimens may go dormant for several weeks in the depths of winter; suspend watering until light levels increase.
- While plants are in active growth, feed with a liquid fertilizer for flowering plants (such as 15-30-15) at half strength.
- Remove spent stalks and leaves with a gentle tug. Note: Oxalis does not require deadheading.
Group several varieties of oxalis with an assortment of other diminutive houseplants:
- Variegated spikemoss (Selaginella kraussiana ‘Variegata’), hardy to 6°C
- Persian violet (Exacum affine), hardy to 10°C
- ‘White troll' browallia (Browallia speciosa ‘White Troll’), hardy to 10°C
Plants, from top: Wine oxalis, 'Copper Tones' oxalis. Photos courtesy of Proven Winners.