Name: shamrock, sorrel, oxalis, Oxalis species.
Height: 15cm tall and up to 20cm in spread.
Foliage: soft, three-lobed leaves; most are green, but some are purple or have coloured central markings.
Climate: temperate to cool temperate.
Soil: well-drained to gravelly loam.
Position: sunny open spot; tolerates light shade but flowers best in full sun.
Flowering: small five-petalled flowers in a variety of colours and combinations, some striped and others with coloured “eyes”.
Feeding: use long-term controlled-release and liquid fertilisers.
Watering: keep moist but not wet; withhold water when bulbs are dormant.
Oxalis, sorrels or shamrocks are ground-hugging plants that grow from bulbs. They usually grow to no more than about 15cm high, although some of the weedy species can be taller. Their leaves are three-lobed, like clover. Although they are mainly green, some types have white, red or brown markings on each lobe, and others are fully coloured, like the purple leaf shamrock pictured. Each leaf is carried on a slender stem arising from the bulb.
Flowers have five petals and range in colour from white through to pinks, mauves and crimson, orange and yellow. They are produced in clusters atop slender stalks. Shamrock bulbs are small and brown, with some also producing a deep, fleshy root.
The more invasive and therefore weedy types of oxalis produce masses of bulbils (tiny bulbs) around the main bulb, which tend to fall off when you try to dig the plants out, spreading through the soil. That’s why it’s so difficult to control oxalis.
The invasive tendencies of soursob (Oxalis pes-caprae), creeping oxalis (O. corniculata) and pink sorrel (O. corymbosa) have seen oxalis in general classified as a weed, but there are many non-invasive species and varieties that make attractive garden or potted plants.
If you do have any of the three weedy oxalis in your garden, try to eradicate them wherever possible. Soursob, pink sorrel or creeping oxalis in garden beds can be dug out or easily treated with a non-selective herbicide, boiling water or a salt solution to kill them. Creeping oxalis in a lawn is a little more complicated. You can try to dig it out, finding the main crown of each plant, but most likely you will need to use a selective broadleaf lawn weeder product.
Many of the ornamental varieties of shamrock thrive in rock or alpine landscapes, where they can be confined, and their flowers fully appreciated.
It’s unlikely you will be able to buy shamrock bulbs, but plants of the best forms will be available from specialist rare plant nurseries. Do check plant labels before buying to ensure you’re not buying one with weed potential!
In warm areas, shamrock will remain in leaf all year round, but in cooler climates where there is a marked winter season, plants may go into dormancy in late autumn. The leaves will yellow and fall off, but don’t discard the plants—the bulbs are still alive! Stop watering until you see the first sign of leaves in early spring, then resume watering again.
Shamrock likes a moist but well-drained soil—the bulbs may rot if they are too wet. Test the soil or potting mix with your finger. If it feels dry, then water. Usually a weekly water from spring to autumn is sufficient.
Don’t water your shamrock plant in the garden or in pots over winter if it loses its leaves and becomes dormant. Move pots to a sheltered spot out of the weather.
Apply a long-term controlled-release fertiliser for flowering plants at the start of spring each year, to plants in the garden as well as those in pots. Supplement this with a water-soluble or liquid fertiliser once a month over the main growing season: spring to early autumn.
Shamrock is reasonably disease and pest free. The only trouble you may encounter is bulbs rotting if the soil is too wet.
Peony: a cool-climate flowering plant with full rose-like blooms from white to deep crimson.
Cyclamen: a tuberous flowering plant with white to cerise flowers on tall stems above grey-green heart-shaped leaves.
Liriope: a grass-like plant with purple flowers, often grown as a border; an excellent foil to delicate shamrock flowers.
Check out our huge range of plants now and get your garden growing!
Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.
When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.