May the Luck of the Irish be with You…..Lucky Shamrocks!

Irish folklore tells that in the 5th century Saint Patrick used the shamrock to explain the Trinity to the Druids. The word shamrock is derived from the Celtic word, “trefoil”, three-leafed, or “little clover”. Trifolium repens is the small white clover that is found in lawns and is used as a green manure cover crop. The Irish consider this to be the true shamrock, and is not the same shamrocks sold in nurseries for Saint Patrick’s Day.

Nowadays, the shamrocks sold for St. Patrick’s Day are members of the Oxalidaceae family. Oxalis are bulbous fibrous- rooted perennials which readily multiply, the genus has over 500 varieties and are native to South Africa and South America. Oxalis plants have photonastic movement which means they respond to light, so on a cloudy day and at night their leaves fold down. Their delicate clover-like leaves range in color from soft green, dark green, purple or a variegated mixture of these colors. Flowers come in a variety of colors: white, cream, yellow, pink, purple or red. The most common Oxalis Shamrocks sold for St. Patrick’s Day are:

Oxalis regnelli (Lucky Shamrock):
Exposure: Indirect sun, light shade
Hardiness: Zones 6-10, anywhere indoors
Height: 6″-8″
Foliage Color: Green
Flower Color: White

Oxalis triangularis (Purple Shamrock):
Exposure: Indirect sun, light shade
Hardiness: Zones 6-10, anywhere indoors
Height: 7″-10″
Foliage Color: Purple
Flower Color: White to light pink

Oxalis deppei (Iron Cross Shamrock):
Exposure: Indirect sun, light shade
Hardiness: Zones 8-10, anywhere indoors
Height: 10″-12″
Foliage Color: Soft Green with purple cross-shaped markings
Flower Color: Rosy pink flowers

Outdoor Care: Oxalis regnelli and Oxalis triangularis are hardy in zones 6-10. There are hardier varieties that can be grown outdoors as a ground cover. These plants are invasive and considered a weed in some areas. Many people grow them as houseplants to maintain control. Pots can be set outdoors in the summer then brought indoors in the fall before frost. Plant shamrocks in 2 parts peat moss to 1 part loam to 1 part sand and grow in bright indirect sunlight. While growing fertilize weekly with a balanced fertilizer. Shamrocks require a dormant period, so let them rest when they start dying back. Restrict all watering and fertilizing. Let the leaves die back naturally and remove them only after they have all turned brown. Let the plant stay dormant for 3 to 4 weeks, then start watering and fertilizing again.

Indoor care: Keep plant in a well-lit location (east or west window) away from hot and cold drafts at temperatures of 60-70F during the day and 55-65F at night. They should be kept barely moist at all times and not allowed to stand in water as that will cause root rot. Fertilize every 2 -4 weeks with a houseplant fertilizer. After bloom, if the plant dies back, allow it to go dormant for 1-3 months. The corms should be kept cool and dry. After dormancy, repot and or divide the corms (optional). When signs of new growth emerge, begin to water, fertilize and move to a sunny spot. For most indoor-grown shamrocks this dormant period occurs 2 to 3 times a year.