Lady Slipper: Unique Sculptural Succulent

Lady slipper is a unique upright plant with charming orange slipper-shaped flowers. It’s a chameleon that takes on different colors and forms depending on its microclimate. Here’s everything you need to know about planting and caring for this low-maintenance Sonoran Desert native.

Lady slipper (Euphorbia lomelii) is one of the most attractive and unique succulents you can grow in your southwest garden. It has rigidly upright stems that sometimes twist and bend into interesting curlicues.

Its leaves are so small you might not notice them, but its green photosynthetic stems pick up the slack. Stems can range from gray-green to nearly red and are covered with a waxy finish that makes them appear frosted.

Its brilliant red-orange flowers are charmingly shaped like slippers or Barbie doll shoes. Flowers are followed by small pods that look like paper lanterns.

Each cluster’s microenvironment dictates its size, color, and growth habit, so that no two lady slipper plants look exactly alike. I have several, and they all have their own personality!

As a native to the deserts and shrubland of Western Mexico, lady slipper tolerates extreme heat and sun. It is an extremely low-maintenance landscape plant. It needs minimal irrigation, requires no pruning, and produces no obvious litter.

Lady slipper flowers are a magnet for hummingbirds but not for insects, which can’t reach the nectar due to the flower’s unusual shape.

Why I Like This Plant

• Attractive plant adds architectural interest all year long
• Charming coral red slipper-shaped flowers
• Low maintenance, needs little water, litter-free
• Hummingbird magnet
• Every plant has a unique form and coloration

Things to Watch Out For

Like all members of the Euphorbia genus, lady slipper exudes milky sap that is toxic to ingest and can be irritating to the skin.

Warning! ⚠️
According to the ASPCA website,
lady slipper is listed as not toxic to dogs.
This is incorrect.
There is more than one plant called lady slipper.
The ASPCA is referring to an entirely different plant.

Optimal Growing Conditions

If you’re thinking of adding a lady slipper to your garden, you need to find a suitable place that will keep your plant healthy and looking good… while minimizing maintenance for you.

Here are the key factors to keep in mind.

Temperature

Lady slipper should be grown in USDA Hardiness Zones 9 – 11. Plants get more cold tolerant as they mature. Young stems can be damaged below 30℉ while mature stems are cold-hardy down to 25℉ and can withstand brief cold spells down to 20℉.

I generally start mine in pots that can be moved to a sheltered patio during cold snaps, then plant them in the ground after a few years.

Sun Exposure

Lady slipper can exist in all light conditions — from full sun and reflected heat to part shade. I have some on the north side of my house that get full sun in the summer and full shade in the winter, and they look beautiful all year.

In very hot microclimates, they appreciate some filtered shade, especially in the afternoon. When grown along a sunny west-facing wall, plants will continue to grow and flower but tend to turn yellow.

Lady slipper respond to “good stress” in some interesting ways. They turn more red when they experience extreme sun or cold. They grow more erect in the sun and more curly in the shade.

Size and Growth Rate

Lady slipper is a moderately fast grower. After a few years, they start sending up new stems to widen the cluster. Clusters are usually 3 feet tall and wide, but I’ve seen them much taller — up to 5 or 6 feet.

Soil

Lady slippers are not particular about soil and grow in any native desert soil, as long as it’s well-draining.

If you grow one in a container, be sure it has good drainage and use specifically formulated cactus soil. Once in pots, they don’t mind being crowded.

Other Location Considerations

Since lady slipper is tall, narrow, and litter-free, it’s a good plant for narrow spaces like along sidewalks or pools. But since it is toxic and can be irritating to touch, keep it where kids and dogs won’t get at it.

Lady Slipper:
The Essentials

Common Name	Lady slipper
Scientific Name	Euphorbia lomelii
Origin	Northwest Mexico
Plant Type	Succulent
USDA Zones	Zones 9 – 11
Cold Hardiness	To 25℉
Flower Color	Red-orange
Flower Season	Spring, summer
Mature Size	3-5′ high x 3-5’ wide
Growth Rate	Moderate
Sun Tolerance	Full, part sun
Water Needs	Low
Pests & Diseases	Root rot if overwatered
Toxicity	Toxic to people, pets, livestock
Wildlife	Attracts hummingbirds Deer, rabbit, javelina resistant

How to Plant

Dig a hole as deep as and twice as wide as the nursery container. Carefully remove the plant from the container, put it in the hole, and press the soil to remove any air pockets.

It’s generally recommended that you backfill with only native soil and not add any amendments. However, good drainage is critical. So if you know your soil is slow draining, amend with coarse sand or small gravel until you have a loose, well-drained mix.

When you plant new lady slippers, they tend to fall over. You can temporarily tie them together loosely or prop them up with rocks or gravel until they can stand on their own. It shouldn’t take long.

Since lady slipper exudes toxic sap, handle with care. When dealing with plants like lady slipper, I put a pair of inexpensive disposable gloves over my regular gardening gloves and then toss them when done. If you get sap on your gardening tools, clean them thoroughly before putting them away.

When to Plant

The best time to plant lady slipper is in April or May when warm soil temperatures encourage root development.

How to Care for Lady Slipper

Whether you’ve recently planted a lady slipper or have an existing plant in your yard, here’s how to take care of it to keep it healthy and looking its best.

How to Water

You’re probably used to giving a plant a good soaking immediately after transplanting, but that isn’t the best practice with succulents like lady slipper. Counterintuitively, it’s best to not water succulents for one to two weeks after planting. Then water every 2 weeks spring through fall, and every 3 to 4 weeks during the winter.

Since lady slippers have shallow roots, there is no need to water deeply. Watering to a depth of one foot is sufficient.

If you’re growing lady slipper in a container, use this watering schedule as a guide.

Spring & Fall	Every 7-10 days
Summer	Every 5-7 days
Winter	Every 10-14 days

Should You Fertilize?

There is no need to fertilize lady slipper if planted in the ground. They get all the nutrients they need from the surrounding desert soil. Fertilizing can result in fewer flowers.

But if you grow one in a pot, fertilize lightly a few times a year when it’s actively growing.

Pruning & Propagation

This plant rarely needs pruning except to remove dead or damaged stems which can be done anytime of the year.

When stems die, they eventually turn into bleached-out sticks. At this point, you can easily snap them off at the base with your hands — they no longer contain any sap.

If you trim back any live stems, you can use them to grow new plants. Simply let the cut ends dry in the shade for a week or so, then stick them into cactus soil and water infrequently.

Lady Slipper Cultivars

If you live where cold limits your ability to grow lady slipper, consider the Chilly Willy lady slipper cultivar.

Pedilanthus macrocarpus ‘Chilly Willy’ is a cold-hardy selection from Tucson’s Civano Growers. Their trials have found that Chilly Willy can survive a full week of temperatures below 32°F and temperature dips as low as 12°F with no damage.

Don’t Confuse Lady Slipper With…

As unique as lady slipper is, it’s still sometimes confused with three other Euphorbias.

Candelilla (Euphorbia antisyphilitica) is an upright succulent that looks like a miniature version of lady slipper. Its stems are half as thick (1/5″ vs 1/2″), it’s not as tall (1-2′ vs 3-5′), and it has tiny “barely there” pink flowers in the spring.

Firesticks (Euphorbia tirucalli) is another upright succulent that is often confused with lady slipper. It has branching, brightly colored stems and looks more like coral than a plant that belongs in the desert.

There is another plant that sometimes goes by the common name slipper plant, or more appropriately tall slipper plant (Euphorbia bracteata), since it can get up to 8 feet tall! It has larger flowers and thicker stems than lady slipper. It has obvious leaves, but when it loses them, these plants can look like a lady slipper on steroids.

And finally, there are plants you won’t find in the desert called lady slipper, such as lady slipper orchid and a lady’s slipper that’s a member of the impatiens genus.

Plant Lover Facts

Lady slipper has several other common names and one notable scientific one.

Most common names are variations of the footwear theme — Lady’s slippers, slipper plant, slipper flower, and the Spanish zapato del diablo (“devil’s shoe”).

One of its former scientific names, Pedilanthus macrocarpus, is still commonly used. Pedilanthus is a composite of the Greek words pedilon (shoe) and anthos (flower).

When research analyzed the milky white sap of lady slipper, it was found to be 6% to 10% rubber.

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Photo Credits

San Marcos Growers

“Euphorbia tirucalli ‘Sticks on Fire‘” by KM is licensed under CC BY 2.0

Arizona State University’s Virtual Library of Phoenix Landscape Plants