Plant care guide
Purple Shamrock Dormancy: Dying Back, Resting and Regrowth
Updated
What should you know about dormancy for a Purple shamrock?
A purple shamrock whose leaves yellow, flop and die back after months of growth is usually going dormant, not dying. It grows from fleshy underground rhizomes that rest for a while, often after heat or dryness in summer or as nights lengthen in autumn, then send up new leaves.
What to do first
Stop watering once the leaves start dying back, remove the dead foliage, and keep the pot cool, dark and fairly dry for about a month. Return it to bright light and water lightly when new shoots appear.
It is alarming to watch a full pot of purple shamrock (Oxalis triangularis) yellow and collapse in a week or two. In most cases the plant is resting, not dying. Don’t throw the pot out.
NC State Extension describes purple shamrock as a rhizomatous perennial. Its rhizomes carry scale leaves that store water and nutrients, a bit like an elongated bulb. The plant may go dormant for a while in autumn, or if it gets too hot or too dry. The leaves die, but the rhizomes stay alive in the pot.
Resting or rotting?
| Sign | Dormancy | Root or rhizome rot |
|---|---|---|
| Timing | After months of growth; often summer heat or autumn | Any time, often after frequent watering |
| Leaves | Yellow, then brown and dry | Yellow and limp while the mix is wet |
| Mix | Normal moisture, or dry | Stays wet between waterings |
| Rhizomes | Firm and plump | Soft, dark, mushy |
Iowa State University Extension says that as plants enter dormancy, the leaves often turn yellow and die. It can be triggered by high temperatures in late summer or by shorter days and cooler nights in autumn. Penn State Extension describes the same yellowing in late autumn as the start of dormancy.
Penn State also warns that overwatering can lead to root rot. If the mix has been staying wet and the plant collapsed quickly, dig gently with a finger and feel a few rhizomes. Firm means resting. Soft and dark means rot: discard the bad ones and replant the firm ones in fresh, well-drained mix.
How to rest a purple shamrock
- Stop watering when the leaves start to die back. University of Wisconsin–Madison Extension says to let the leaves dry out and turn brown. NC State says to cut back on watering and wait for new growth.
- Remove the dead leaves once they have dried.
- Move the pot somewhere cool and dark. Wisconsin, Iowa State and Clemson Cooperative Extension all advise a cool, dark spot. Iowa State says to keep it relatively dry until new growth begins.
- Stop fertilizing. Penn State says to stop both watering and fertilizing during dormancy.
How long does it last?
Wisconsin says most shamrocks rest for 2–3 months, but purple-leaf types only need about a month. Iowa State gives 1–3 months for Oxalis in general. Penn State says one to several months.
So check your purple shamrock after about four weeks. If you see pale shoots at the surface, it is ready to wake up.
Waking it up
- Return it to bright light. Iowa State and Clemson suggest bright, indirect light. Wisconsin suggests a bright, sunny window.
- Water lightly at first. Iowa State says to water lightly once growth emerges, then keep the mix slightly moist but well drained.
- Repot now if needed. Wisconsin suggests fertilizing or repotting before returning the pot to the window. Set the rhizomes just under the surface of a well-drained soilless mix.
- Feed once leaves are growing. Clemson suggests a houseplant fertilizer once or twice a month while the plant is actively growing or flowering.
Don’t overpot. Iowa State, Clemson and Penn State all note that shamrocks seem to do best slightly pot-bound.
Dividing while it rests
Dormancy is the easiest time to make more plants. Wisconsin says oxalis are easy to propagate when dormant by dividing the many small bulbs, and potting them in small groups. NC State adds that you can divide the rhizome or break off the scale leaves, which will produce new plants.
Can you stop it going dormant?
Not entirely, and you don’t need to. Cool conditions help keep plants in leaf longer. Wisconsin suggests days no warmer than 24 °C (75 °F) and nights 8–14 °C (15–25 °F) cooler. Iowa State suggests nights around 16 °C (60 °F) and days around 21 °C (70 °F). NC State and Iowa State both name heat as a trigger, so a pot in a hot summer window may shut down early.
Pets
The ASPCA lists Oxalis as toxic to dogs, cats and horses because of soluble calcium oxalates. Signs include drooling and tremors, and kidney failure is rare. NC State notes that serious effects usually need large quantities. Keep the pot, and any rhizomes you divide, away from pets.
For other toxic houseplants and their signs, see our pet toxicity guide.
Related guides
Other purple shamrock problems we cover: leggy growth, drooping.
References
- NC State Extension Gardener Plant Toolbox: Oxalis triangularis
- University of Wisconsin–Madison Extension: Shamrocks, Oxalis spp.
- Iowa State University Extension: Growing Shamrocks Indoors
- Penn State Extension: The Botany Behind the Shamrock
- Clemson Cooperative Extension: Shamrocks and St. Patrick’s Day
- ASPCA: Shamrock Plant
How this guide was put together: NC State Extension, University of Wisconsin–Madison Extension, Iowa State University Extension, Penn State Extension, Clemson Cooperative Extension and ASPCA guidance.