Oxalis, often recognized by its clover-like foliage, is a genus of flowering plants grown from small bulbs or tubers. Also called wood sorrel or shamrock plant, Oxalis is popular for both indoor containers and garden beds due to its delicate appearance and vibrant colors, including shades of green, purple, and burgundy. Successful planting of these underground structures is necessary to ensure Oxalis thrives and produces its signature clusters of leaves and flowers. Understanding the correct environment and planting technique helps transition these bulbs from dormancy to full, healthy growth.
Preparing the Planting Environment
The optimal time to plant Oxalis outdoors is in the spring, after the danger of the last hard frost has passed. If growing Oxalis as a houseplant, the bulbs can be planted any time of the year in an indoor container environment. Selecting the right location is important, as Oxalis prefers bright, indirect light to partial shade, translating to about four to six hours of sunlight daily. Shield them from intense, direct afternoon sun, which can easily scorch the delicate leaves and cause the plant to wilt.
The soil must be well-draining to prevent the small bulbs (technically corms or rhizomes) from rotting, a common issue with this plant. For container planting, use a standard, porous potting mix amended with materials like perlite or sand to increase aeration and drainage. When planting directly into a garden bed, ensure the native soil is loosened and enriched with compost. Oxalis tolerates a slightly acidic to neutral soil pH, typically ranging between 6.0 and 7.0.
Determining Planting Depth and Spacing
The most common recommendation for planting depth is 1 to 2 inches (2.5 to 5 centimeters) below the soil surface. Planting too deeply delays or prevents the emergence of sprouts, as young shoots use up stored energy before reaching the light. Conversely, planting too shallowly can cause the bulbs to dry out or become unstable as the plant grows.
The orientation of the Oxalis bulb, which often resembles a small, segmented pinecone, is important for successful sprouting. The narrow or pointed end, where the growth tip is located, should face upward in the soil. While the plant may still grow if planted sideways or upside down, the process will be slower and less efficient as the sprout must redirect its growth.
Adequate spacing between the bulbs is necessary to allow for the plant’s natural tendency to spread and form dense clusters. A typical spacing of 3 to 5 inches (8 to 12 centimeters) apart provides enough room for individual plants to develop fully and ensures good air circulation. For a fuller, more immediate display in containers or small areas, plant them closer together in groups of three to five bulbs.
Initial Care and Encouraging Growth
Immediately after placing the bulbs in the soil, water thoroughly yet gently to settle the surrounding soil particles and initiate growth. The goal is to moisten the soil without causing saturation or allowing the bulbs to sit in standing water. Overwatering is the most frequent cause of bulb rot in Oxalis, so allow the top inch of soil to dry out slightly before the next watering.
Optimal temperatures are necessary for the emergence of new growth, with most varieties preferring a range between 60°F and 75°F (15°C to 24°C). Under the right conditions, expect to see the first delicate shoots and foliage emerge within two to four weeks of planting. Avoid fertilization during this initial sprouting phase to prevent burning the fragile new roots.
Once the plant has established foliage and begins active growth, apply a light feeding with a diluted, balanced liquid fertilizer, such as a 10-10-10 formula, monthly throughout the growing season. Oxalis often enters a period of natural dormancy, usually triggered by extreme heat, lack of water, or cold. If the foliage unexpectedly dies back, simply withhold water and fertilizer; the bulbs will rest underground, ready to sprout again when favorable conditions return.