How to Plant Shamrock Bulbs

The shamrock (Oxalis acetosella), with its slender stems and familiar heart-shaped or rounded leaves, works well as a low ground cover or garden border. The plant is also known as wood sorrel and grows as a perennial in U.S. Department of Agriculture plant hardiness zones 6 through 11. You can grow the bulbs indoors in planters so the plants are in bloom for St. Patrick's Day.

Shamrock bulbs are small and form in clusters. The clusters break apart easily so you can plant the individual bulbs. Choose bulbs that are fully formed, firm and plump. Avoid bulbs that are discolored, mushy or malformed.

Gnats and other insects may gather around rotting flower bulbs. Do not select bulbs from bins where insects are present.

In their native habitat, shamrocks do well in woodland areas that receive partial shade or full sun for part of the day. The amount of blooms produced is in direct correlation to the amount of sunlight the plant receives -- more sunlight means more flowers. Choose a planting site that has rich, moist soil with good drainage. Standing water causes the bulbs to rot.

Increase drainage in the soil by adding organic material such as peat moss, dried leaves or compost.

Hand spade

Garden rake

Dig a hole approximately 1/4 inch deeper than the bulbs. The shamrock bulbs should be just below the soil surface, about an inch deep.

Rake loose soil over the bulbs to cover them.

Water the planting area well so the soil settles around the bulbs.

Keep the soil moist until the bulbs sprout.

Water the shamrock plants as needed, so the soil barely dries between watering.

Shamrock bulbs grow best in groups when grown in containers. Plant five or six bulbs in a 4-inch pot that has drainage holes in the bottom. As with outdoor planting, plant the bulbs about an inch deep in the soil. Water the bulbs and set the pot in a bright window.

For indoor growing, use a soilless potting mixture

Once the plants start growing, water the shamrocks when the soil is almost dry. Feed the plants with a general purpose fertilizer at a rate of about 1 tablespoon per gallon of water, or according to the package directions. Discontinue feeding the plants once the blooms start fading.

Shamrocks can suffer from root rot if the soil remains too moist. Yellowing or wilted leaves can be a sign that the soil is too wet.

Shamrocks need a period of dormancy for healthy indoor growth. When the blooming stops, discontinue watering. Allow the plants to die back. Trim off the dead plant matter and move the pot into a dark, cool area for two to three months. Move the pot back into a bright window once the bulbs start showing signs of growth. Start the watering and feeding cycle again for a new round of blooms.

Propagate the shamrocks by dividing the bulbs at the end of the dormant period. Plant the bulbs in pots as directed previously.