Oxalis deppei "Iron Cross" originated in Mexico and South America. The plant grows 12 inches tall from perennial bulbous root stock. The oxalis leaf resembles a clover leaf with three heart-shaped leaflets. The name Iron Cross comes from the dark purple cross pattern in the centre of the leaves. The edible leaves and stalks provide a tangy taste for salads and soups. Dark pink oxalis flowers dress up desserts and summer salads. The warm climate oxalis variety grows in U.S. Department of Agriculture zones 8 through 10.
Plant Iron Cross in a sunny spot. Most oxalis varieties prefer shade, but this one is an exception. Select an area where the soil drains well and has a light, loamy or sandy texture.
Dig holes as deep and slightly wider than the root ball. Space the planting holes 6 to 12 inches apart.
Push soil around the roots and pat down the soil gently with your hands. Apply water to the planting area to settle the roots and reduce transplant shock.
Fertilise the plants once a month using a balanced fertiliser. The University of Oklahoma Department of Botany and Microbiology recommends diluting the fertiliser to half strength.
Water Iron Cross when the top 1 to 2 inches of soil start to feel dry under your fingers. Soak the area to a depth of 4 to 6 inches, then allow the soil to dry out before you water again.
Divide Iron Cross plants in the spring when new growth begins to appear. Dig up a section of a plant, and pull it or cut it into sections, each containing three or more growing shoots.
Replant the divisions a new area in the garden or in pots. Use a mix of 2 parts peat to 1 part loam.
Oxalis "Iron Cross" grows poorly in wet, heavy clay soil and shade.