Purple Shamrock

Purple Shamrock is formally known as oxalis triangularis. It is endemic to Brazil. Historically it was grown as a house plant in the United States but has moved into the yard and adapted in Texas. It works best in zones 8a–11, preferably in light shade. THIS IS A TRUE DROUGHT RESISTANT PLANT! GREAT NEWS FOR TEXAS.

The purple shamrock (or sometimes referred to as a black shamrock) and as pictured below does very well in full sun! It is pictured in April, May and June here. You are able to watch the gold lantana expand and eventually cover the shamrock as the summer progresses.

Black Shamrock is of the same family. Velvet Oxalis regnellii or Black Shamrock is the darkest of the Purple Shamrocks. Velvet shamrock runs a close second.

Oakleaf Hydrangea, Purple Shamrock and Oxalis

Purple Shamrock (Oxalis triangularis) is a striking ornamental plant admired for its deep purple, butterfly-shaped leaves and delicate pink or white flowers. It’s popular both as a houseplant and in outdoor gardens in mild climates — including parts of Texas.

Quick Profile: Purple Shamrock (Oxalis triangularis)

Common Names: Purple Shamrock, False Shamrock, Love Plant
Botanical Name: Oxalis triangularis
Foliage: Triangular, deep purple leaves that open during the day and close at night (nyctinasty)
Flowers: Pale pink or white, blooming intermittently
Height/Spread: 6–12 inches tall, spreads 12–18 inches

Recognition & Awards

While not as highly decorated as larger landscape plants, Oxalis triangularis is widely admired and recognized for its decorative foliage and ease of care, especially in containers and shade gardens. Notable mentions:

Royal Horticultural Society – Award of Garden Merit (AGM)

Awarded for:
- Exceptional ornamental appeal
- Indoor/outdoor versatility
- Long bloom time
- Low maintenance
The RHS specifically awarded the Oxalis triangularis subsp. papilionacea cultivar.

Performance in Texas

Ideal for East and Central Texas gardens in shady spots or as a container plant
Prefers morning sun and afternoon shade outdoors; full sun may scorch leaves in summer
Grows well indoors near a bright window
Goes dormant in extreme heat or cold but regrows from bulbs

Care Tips

Soil: Well-drained, rich soil
Watering: Keep soil lightly moist; allow topsoil to dry between waterings
Light: Bright, indirect light indoors; partial shade outdoors
Dormancy: Leaves may die back in summer or winter — allow plant to rest, then resume watering after a few weeks

Purple Shamrock Lantana and Red Yucca

I stopped using yellow lantana many years ago. For the most part it acts as a perennial in Texas, but that allows its root structure to become so established that it grows too large August onward becoming unwieldy for my eye. It’s a good and easy perennial, to be sure. Perhaps I just became bored with it. But if you are just starting out and want a quick, easy impact, go for it! Clearly, the lantana is on its way to taking over the purple shamrock — and perhaps that is good. It will allow the purple shamrock to go dormant.

Purple Shamrock – Oxalis regnellii atropurpurea. In Texas purple shamrock blooms on St. Patrick’s day. This gives you a good idea of when it is at its peak in Texas! As you can see in the June image above, purple shamrock has stopped blooming but it’s leaves have become more profuse! Purple shamrock is grown for its leaves and not its blooms, though the blooms are very sweet.

Plant with Osmocote

The only fertilizer I use with perennials and annuals. I always put a scoop of Osmocote, mix in some water retention crystals with perennials.

Purple Shamrock as an Accent

Purple shamrock mixed with Holly Fern.

More Purple Shamrock!

Purple shamrock with miniature pink crape myrtle makes a lovely combination.

Purple Shamrock with Dwarf Pink Crape Myrtle

Miniature Pink Crape Myrtle: More Here

Centennial, a dwarf crape myrtle is a perfect contrast for purple shamrock.

Yew and Purple Shamrock a Classic Combination

Relatively little care is required during the growing season. Water strongly the first two years while they become established. Once the shamrock goes dormant, you will observe leaf drop, trim the vegetation down. In Texas you cannot always stop watering Purple Shamrock because of its proximity to other plants. However, ideally, during the dormancy period let it wilt and lose leaves.

Purple shamrock, spreading yew and Japanese Maple.

Propagation Purple Shamrock

Purple Shamrock grows from tiny bulbs the size of your thumbnail. Propagation is by bulb division. Purple Shamrock (like all bulbs) experiences a dormancy period on a regular basis. At the end of the dormancy period, the bulbs can be unearthed, side bulbs can be cut and replanted.

Above Purple Shamrock nestles amongst the rocks.

During the day you will see the Purple Shamrock leaves stand up and pay attention and wilt in the evening. The leaves of the Purple Shamrock respond to light levels, opening in high ambient light (in the day) and closing at low light levels (at night). This movement is powered by changes in turgor pressure in cells at the base of the leaf. It is an example of photonasty. See cool video below of this process.

Purple Shamrock with Holly Fern in Perennial Shade Garden Setting.

Silver Shamrock – Lavender Shamrock – Mahogany Shamrock

Purple is not the only color! Try these sweet shamrocks as well.

Silver Shamrock

Lavender Shamrock

Mahogany Shamrock

Purple Shamrock and Pets: Known to be poisonous to cats and dogs.

Read more about poisonous plants here …

This is one reason to consider Purple Heart rather than Purple Shamrock. See Purple Heart below.

Shade Garden Perennial Purple Shamrock with Holly Ferns.

Purple Shamrock and Purple Japanese Maple with Hostas

A perfect situation for purple shamrock is morning sun! But that’s a perfect situation for most plants in Texas. Dappled shade works. However, with lots of water it will survive in full sun. LOTS OF WATER. Fundamentally, this is a bulb about the size of your thumbnail. Consequently, it will go semi-dormant in Texas several times a year. They are just ‘resting’.

Purple Shamrock in Perennial Bed - May Images

Purple shamrock lining a bed of hostas and hydrangeas.

Purple shamrock tucked in with annuals is a great idea in the first years while the shamrock is becoming established. You will be watering and fertilizing your annuals and the shamrock will benefit as well. In a few years the purple shamrock will become stronger and more established and you will require fewer annuals.

Purple Shamrock mixed with annuals while they become established.

Purple Shamrock Summary: I love this precious little plant. Every year in the fall I dig it up, separate it, and tuck it around the garden near the border in the shade.That’s coral bells Palace Purple Heuchera beside the purple shamrock. I have never had long term luck with coral bells. I treat them like an annual but perhaps someone else might do better. THey are very popular at the plant stores.

Purple Heart Perennial

Purple Heart is another perennial that works better in full sun. Purple Heart is a more compact and reliably broader leafed version of Purple Wandering Jew.

Purple Heart is slightly more elevated than Purple Shamrock.

Purple Heart for the Perennial Shade Garden

Purple Heart (Tradescantia pallida ‘Purpurea’) with the same format — covering awards, Texas performance, care, and design uses.

Quick Profile: Purple Heart

Common Names: Purple Heart, Purple Queen, Wandering Jew (older name, now avoided)
Botanical Name: Tradescantia pallida ‘Purpurea’
Foliage: Bold, deep purple lance-shaped leaves
Flowers: Small pink blooms, especially in summer
Height/Spread: 12–18 inches tall, can spread 2+ feet

Recognition & Awards

Texas Superstar® Plant

Awarded by: Texas A&M AgriLife Extension
Why It Earned This Title:
- Heat and drought tolerant
- Thrives in Texas’ full sun or part shade
- Fast-growing and colorful groundcover
- Excellent container or border plant
Tested Statewide: Proven to perform in trials across all Texas regions

Royal Horticultural Society – Award of Garden Merit (AGM)

Tradescantia pallida also recognized in UK for:
- Long-season interest
- Resilience and low maintenance
- Indoor/outdoor use versatility

Performance in Texas

Thrives in USDA Zones 8–11 (North Texas southward; freezes back in Zone 7 but often returns)
Excellent in full sun (gets deeper purple) or part shade
Can be used as a groundcover, hanging basket plant, or in mixed containers

Purple Persian Shield

Purple Persian Shield makes a strong statement. Here you see it combines with traditional Purple Wandering Jew.

Persian Shield (Strobilanthes dyerianus)
Persian Shield is a striking tropical foliage plant valued for its iridescent purple leaves with silvery highlights and deep green veining. Though it occasionally produces tubular violet-blue flowers, it is primarily grown for its vibrant foliage.

Botanical Name: Strobilanthes dyerianus
Common Names: Persian Shield, Royal Purple Plant
Foliage: Broad, lance-shaped leaves with a metallic sheen
Size: Typically grows 2–3 feet tall and wide in containers; may reach up to 4 feet in ideal outdoor conditions

Awards and Recognition
Persian Shield has earned the Royal Horticultural Society’s Award of Garden Merit for outstanding garden performance. It is also frequently featured in botanical gardens, public displays, and university trial gardens for its dramatic impact and reliable performance in shaded landscapes.

Performance in Texas
Persian Shield performs best in East and Central Texas as a shade-tolerant annual or tender perennial. In Zone 9 and warmer (such as Houston or coastal Texas), it may survive mild winters with protection. It prefers partial to full shade and is especially effective in containers or shaded borders. Morning sun is acceptable, but the plant should be shielded from the intense afternoon heat.

Care Guidelines

Soil: Prefers rich, well-draining soil with consistent moisture
Light: Grows best in partial shade; too much sun can scorch the foliage
Watering: Keep evenly moist but not soggy; avoid letting the soil dry out completely
Fertilization: Use a balanced fertilizer monthly during the growing season for best color
Maintenance: Pinch back regularly to encourage bushy growth; prune leggy stems
Winter Care: In cooler zones, bring indoors before frost and grow as a houseplant in bright, indirect light

Landscape and Design Use
Persian Shield is a bold accent in shaded landscapes and container combinations. It pairs well with other shade-loving foliage plants like coleus, caladiums, and ferns. It provides dramatic contrast and texture in tropical-themed or woodland gardens.

See more on this Perfect Perennial Shade Garden Here.