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Shamrocks for Year-Round Luck

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Shamrocks for Year-Round Luck

Everyone knows that you don’t have to be Irish to wear green on St. Patrick’s Day, nor do you need a green thumb to grow shamrocks inside or outdoors.  As a matter of fact why not try both this year.  With the popularity of container gardening exploding, the hunt for suitable pot plants is intense.  Oxalis (commonly sold as shamrock plants) coordinate beautifully in mixed containers and summer window boxes.  They can’t be beat for their stunning foliage and ease of care.

Oxalis is native to South Africa and the Americas.  They are tender perennials with clover-like leaves that grow from modified stem tissue called tubers.  Most produce mounds of attractive, shamrock-shaped leaflets, four to 12 inches tall, with a profusion of 1- to 2-inch blooms. The dainty flowers are borne in small clusters on slender stalks held slightly above the compound leaves.  The flowers are typically shades of pink and lavender/purple to yellow and white.  It is the remarkably distinctive and attractive foliage of many cultivars that makes oxalis such a good container plant.

Because they are native to warm and often hot climates, oxalis are not reliably hardy here in the Midwest and must be treated as either an annual or over-wintered indoors.  Oxalis thrive in part shade, preferring well-drained soil that is kept evenly moist, but not wet.  These plants will wilt if the soil is allowed to dry out, especially during the hottest part of a summer’s afternoon, so it’s best to protect them from exposure to strong sunlight.  Regular fertilization of these plants during the growing season will ensure the best possible performance. One rather charming trait of oxalis is that the leaves are capable of movement, folding down at sunset, when drought-stressed, or in heavy rain.

The leaves of oxalis can be bright green, steel blue, deep purple, and maroon, or even interesting combinations of these colors.  A few newer introductions sport light chartreuse leaves, as well as green leaves that are splashed with silver. Some popular varieties with attractive foliage available this time of year at florist shops and grocery stores are:

Oxalis tetraphylla ‘Iron Cross’ – green leaves with dark burgundy markings and pinkish-red blooms

Oxalis triangularis ‘Charmed Wine’ – violet-purple foliage and pinkish-white blooms

Oxalis triangularis ‘Charmed Jade’ – green leaves with silver sheen and blush-pink blooms

Oxalis vulcanicola ‘Zinfandel’ – purplish-black foliage and yellow blooms, grows in sun or partial shade.

If you want to save oxalis year to year, be sure to dig the plant from the container before the first frost. One method of storage is to remove all the foliage, brush the soil from the tubers, wrap when dry in newspaper and overwinter in a cool, dry place.  Or, if in a pot, move the tuber-filled container to a place cool enough to keep the plants dormant, but warm enough so they don’t freeze.  An insulated but unheated garage or porch works well.  Water very sparingly – just enough to keep the tubers from desiccating.  Oxalis also can be a houseplant; however, indoors it can go dormant two or three times a year for several months at a time.  When it starts to go dormant, the foliage will die back.  Reduce watering and stop fertilizing the plants at this time.   When you see new growth, begin the water-fertilizer regimen again.  Indoors, place oxalis in a bright window, but out of direct sun.

Special note:  Oxalis can be poisonous to pets.  The leaves taste extremely sour due to their high oxalic acid content, but some pets eat them anyway.  If you notice a pet grazing on your shamrock plant, immediately move it to where your animals cannot reach it.

Give in to the impulse to buy a shamrock plant this year.  Enjoy the bit of Irish spring it brings indoors and the summer long beauty it adds to your outdoor container combinations as well.

Jan Gowen, Kemper Horticulture Assistant

| Categories: Spring | Tags: Oxalis, container plants, Shamrock | View Count: (6780) | Return
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