How to Plant Shamrocks in Zone 6

White flowering shamrock plants are an attractive border.

Shamrock plants grown outdoors can make interesting and attractive ground cover or borders for flower beds, but they do have a tendency to spread. They may become invasive if not contained. Many perennial shamrock cultivars require frost-free regions to grow well, making it frustrating for gardeners in USDA hardiness zone 6 to successfully incorporate the plant into their landscape designs. Fortunately, there are two varieties, Oxalis acetosella (Irish shamrock) and Oxalis Triangularis (purple shamrock), that are hardy and will easily survive growing in colder zones.

Things You'll Need

• Shamrock rhizome
• Organic material, dried leaves, grass clipping
• Shovel
• Hand trowel
• Water
• Shears
• Mulch

Instructions

1. Prepare the planting area when the threat of freezing has past and the soil is workable. Select a planting area that receives full or partial sun, though more sun will produce more flowers and lush foliage. Grow shamrocks in loamy, well-draining soil. Amend the planting area with 2 to 4 inches of organic material that is worked into the soil with a shovel to a depth of 6 to 8 inches.

2. Use a hand trowel to dig a shallow hole that is slightly larger than the shamrock rhizome and about 2 inches deep.

3. Place the shamrock rhizome in the bottom of the dug hole; it does not matter what side of the shamrock rhizome is up. Cover the rhizome with soil and pat the soil down with your hand. The rhizome should now be planted about 1 inch deep.

4. Water the planted shamrock rhizome so the soil is moist, not soggy. Continue to regularly water the plant to maintain a moist soil, never overwatering, which could cause the rhizome to rot. In two to four weeks you will see shamrock foliage emerge. Flowering will occur in late spring through early summer, but the attractive shamrock foliage continues throughout the growing season.

5. Use shears to cut the dead and dying foliage from the shamrock plant at the end of the season when the foliage has turned yellow and brown. It is important to allow the foliage to naturally die before trimming it off the plant. The foliage gives food to the rhizome for the following year's growth.

6. Place 3 to 5 inches of organic mulch, like dried leaves and grass clippings, over the trimmed shamrock plants to protect them from hard freezing. Shamrocks need two to three months of dormancy during the winter. Purple and Irish shamrock plants are hardy in USDA zone 6, but adding a layer of mulch over the dormant plants ensures that the plants will not be harmed should an unexpected hard freeze occur.

References

• EasytoGrowBulbs.com: Oxalis Growing Instructions
• Canadian Gardening; Shamrocks; Anne Marie Van Nest
• The Garden Geeks: Plant Guide-Oxalis Acetosella Var. Purpurascens