Birthday
HydrangeasThis article was prepared with the support of UFL flower delivery. Oxalis triangularis, also called purple shamrock, false shamrock or butterfly plant, comes from South America. Its three-part leaves in deep purple or green look like butterfly wings, and delicate white or pale pink flowers rise above them. The plant is easy-going, but it has one feature worth knowing about in advance: a dormant period.
Why it is a "day and night" plant
In the morning the leaves open, and in the evening or on dull days they fold up like the wings of a sleeping butterfly. This is called nyctinasty: the movement is caused by changes in water pressure in cells at the base of the leaflets. The flowers close at night too, which is why oxalis is sometimes called a living clock.
Interestingly, the shamrock, Ireland's symbol, is usually linked with clover, although pots of oxalis are often sold for St Patrick's Day as well.
Caring for the butterfly plant
Light and temperature
Oxalis needs bright, indirect light: an east- or west-facing window, or a south window with shade from the midday sun. In shade the stems stretch and the leaves become small and pale. It is comfortable at 20–25 °C in summer and 12–18 °C in winter.
Watering and humidity
Water when the top 1–2 cm of compost is dry. The small bulbs rot easily, so empty the saucer. Misting in hot weather helps but is not essential.
Feeding
From April to September feed every 2–3 weeks with a houseplant fertiliser at half strength. Do not feed during dormancy.
Repotting and compost
Repot young plants every spring and mature ones every 2–3 years. Use a light houseplant compost with sand or perlite and a drainage layer. A wide, shallow pot works best. Plant the bulbs about 1 cm deep, 8–10 per pot.
Dormancy: wilting leaves are normal
Once a year, often in winter or after a long flowering period, oxalis drops its leaves. It is resting, not dying. Stop watering, move the pot somewhere cool and dark for 1–2 months, and when new shoots appear bring it back into the light and resume watering.
Propagation
The easiest way is to divide the bulbs when repotting in spring. You can also root a single leaf with its stalk in water. Oxalis grows quickly and forms a lush clump within 1–1.5 months.
Pests and safety
Aphids, spider mites, whitefly or scale occasionally appear and can be treated with an insecticide. The leaves contain oxalic acid and oxalates: small amounts are edible, but they are harmful for people with kidney problems, and the plant is toxic to cats and dogs.
FAQ
Why doesn't my oxalis fold its leaves?
If it sits under bright artificial light around the clock, its rhythm is disrupted. Give it a natural day and night cycle.
Why are the leaves green, not purple?
There are green-leaved forms, and purple varieties fade when they lack light.
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Author: Maria Svitlovir
Graduated from Taras Shevchenko National University of Kyiv, Institute of Biology and Medicine (2001). BSc in Biology, MSc in Horticulture. Writes about plants, works at a garden centre selecting and repotting plants, and contributes to plant reference guides.
