The Oxalis tetraphylla ‘Iron Cross’ is a popular bulbous perennial prized for its unique and decorative foliage. It is often called the “Good Luck Plant” due to its distinctive four-leaf clover shape, which is rare in the Oxalis genus. Each bright green leaflet features a deep purple or maroon blotch at its base, creating a striking cross pattern in the center. Beyond the foliage, the plant produces sprays of trumpet-shaped, bright pink flowers from early summer until the first frost.
Preparing the Planting Environment
The ‘Iron Cross’ Oxalis requires bright, indirect light to maintain its vibrant leaf color and compact growth habit during its active growth period. Placing the plant in an east or west-facing window indoors provides sufficient light. Outdoor planting requires dappled shade or morning sun, as intense afternoon sunlight can scorch the delicate leaves.
A loose, well-draining potting mix is necessary to prevent rot, such as a standard mix amended with perlite or coarse sand to improve aeration and drainage. Whether planting in a container or in the garden, the soil must never become waterlogged. The small bulbs should be planted just beneath the soil surface, typically one to three centimeters deep, with the pointed end facing upward.
Essential Daily and Weekly Maintenance
Routine care during the spring and summer growing season focuses on careful hydration and nutrient delivery. The most common mistake is overwatering, so use a “soak and dry” method. Allow the top inch of the soil to dry out completely before watering thoroughly, ensuring that any excess water drains away.
A regular fertilization regimen supports the plant’s vigorous growth and continuous flowering. During the active growth period, feed the Oxalis once a month using a balanced, water-soluble liquid fertilizer. Dilute the fertilizer to half the strength recommended on the label to prevent the buildup of salts and potential root burn. Fertilizing should cease entirely as the weather cools in late summer or early fall when the plant naturally begins to slow down.
The ‘Iron Cross’ prefers average household temperatures between 60 and 75 degrees Fahrenheit and must be protected from frost. While it tolerates normal room humidity, its leaves will fold up at night in a process called nyctinasty. Removing spent flowers, known as deadheading, encourages the plant to put energy toward producing new blooms and foliage.
Managing the Annual Dormancy Cycle
The ‘Iron Cross’ Oxalis is a tuberous plant that requires a period of dormancy for its long-term health. This resting phase typically begins in late summer or fall, indicated by the leaves starting to yellow, wilt, and die back. This response signals that the plant is preparing to store energy in its bulbs for the next growing cycle.
When the foliage begins to decline, stop watering and fertilizing completely to induce dormancy. The foliage can be trimmed back to the soil level once it has fully browned. The pot should then be moved to a cool, dark, and dry place, such as a basement or garage, where temperatures remain above freezing.
The plant should remain in this dormant state for two to three months. To reawaken the Oxalis, move the pot back into a bright location and resume watering sparingly at first. As soon as new growth is visible, increase watering to the normal level and resume the monthly feeding schedule.