Why Are Mesembs So Hard to Care For?

Mesembs are some of the strangest and most fascinating plants you can grow. They can look like smooth stones, tiny windows, alien fingers, or oddly shaped pieces of living sculpture. Plants like Lithops, Conophytum, Fenestraria, and Pleiospilos have evolved to survive some incredibly harsh environments.

And that's exactly why they can be so difficult to grow at home.

The problem isn't that mesembs are inherently fragile. In many ways, they're incredibly tough plants. The problem is that their idea of survival is very different from what most houseplants expect.

Give a typical houseplant water when the soil looks dry and it perks up.

Give a mesemb water at the wrong time, and you may be looking at a dead plant a few days later.

So why are mesembs so difficult to care for?

Let's take a closer look.

What Are Mesembs?

"Mesemb" is a general term commonly used for plants in the Aizoaceae family, a diverse group of succulents native primarily to southern Africa.

The group includes some of the most unusual succulents available to collectors.

Some of the best-known mesembs include:

• Lithops — commonly called living stones

• Conophytum — tiny paired-leaf succulents with incredible flowers

• Fenestraria — often called baby toes

• Pleiospilos — split-rock-like plants

• Cheiridopsis

• Argyroderma

• Dinteranthus

• Titanopsis

Despite their differences, many share an important characteristic:

They are adapted to environments where water is unpredictable and seasonal.

Understanding that is the key to understanding their care.

The Biggest Problem: Water

If there's one thing that causes more mesemb deaths than anything else, it's probably watering at the wrong time.

Mesembs have evolved to take advantage of specific periods when moisture is available. They aren't necessarily designed to receive small amounts of water every week throughout the year.

Many species have very pronounced growth and dormancy cycles.

During active growth, they may appreciate regular watering.

During dormancy, that same water can become a serious problem.

And this is where things get tricky.

A Mesemb Can Look Like It Needs Water When It Doesn't

This is one of the biggest traps for beginners.

A mesemb may become wrinkled, smaller, or softer-looking during part of its natural cycle.

Your instinct may be:

"It needs water."

But sometimes the plant is doing exactly what it's supposed to do.

Lithops are an excellent example.

As an old pair of leaves is consumed, the plant can look increasingly shriveled while the new leaves develop underneath.

Watering during this process can interfere with that natural cycle.

The plant looking thirsty doesn't always mean it wants water.

That's a difficult concept when you're used to growing ordinary houseplants.

Mesembs Have a Very Different Relationship With Their Leaves

Many mesembs essentially recycle their old leaves.

Instead of simply growing new leaves on top of old ones, the plant can absorb the water and nutrients stored in older tissue and use them to produce new growth.

This is particularly obvious with Lithops.

Eventually, the old leaves become dry and papery while the new pair emerges.

This can be alarming the first time you see it.

It can look like your plant is dying.

In reality, the plant may simply be going through a normal seasonal transition.

Learning to recognize these growth cycles is one of the most important skills when growing mesembs.

Their Roots Don't Like Sitting Wet

Another reason mesembs can be challenging is their root system.

These plants are adapted to environments where water can arrive quickly and then disappear just as quickly.

That means the growing medium needs to drain extremely well.

A heavy, moisture-retentive potting soil can stay wet around the roots for far too long.

And once the roots remain wet without sufficient oxygen, problems can develop quickly.

This is why mesemb growers often use very mineral-heavy growing mixes.

A mix containing materials such as:

• Pumice

• Grit

• Lava rock

• Coarse sand

• Limestone

• Other mineral components
  

can provide the drainage and air space these plants need.

The exact mix isn't universal. Different species and growing conditions can require different approaches.

But the general principle is simple:

Mesembs generally don't want to live in soggy soil.

Light Is Just as Important as Water

Water gets most of the attention, but light is another major piece of the puzzle.

Mesembs generally need very bright light to maintain compact, attractive growth.

When light levels are too low, some species can stretch or become elongated.

That's especially frustrating with plants that are supposed to stay compact and sculptural.

A Lithops that grows into a tall, stretched-out plant doesn't look much like the little stone it was designed to imitate.

If you're growing mesembs indoors, a very bright window may work, but supplemental lighting can make things much easier.

Heat Doesn't Always Mean Growth

Here's another misconception that can cause problems.

You might assume:

Hot + sunny = growing season.

For many mesembs, that's not necessarily true.

Some species have dormancy periods that coincide with hot or dry conditions in their native habitats.

That means a plant sitting in a warm, sunny window during summer may not necessarily want to be watered more frequently.

This is one of the reasons it's so important to learn the specific species you're growing.

"Mesemb" covers a huge variety of plants.

There isn't one universal watering schedule that works for all of them.

The Pot You Grow Them In Matters

For plants with unusual watering requirements, the container can make a surprisingly large difference.

A large pot filled with moisture-retentive soil can stay wet for a long time.

A shallow, appropriately sized pot filled with a fast-draining mineral mix can dry much more quickly.

For small mesembs, pot size should generally be proportional to the plant and its root system rather than simply choosing a huge container to give the plant room to grow.

This is one reason mesembs look particularly good in shallow, well-designed pots.

The container becomes part of the presentation.

The plant is already living sculpture.

The right pot can make it even better.

Why Beginners Often Kill Mesembs With Kindness

This may be the most frustrating part of growing these plants.

Most plant problems come from trying to help.

You see wrinkles.

You water.

The plant looks worse.

You water again.

Eventually, the roots fail.

With mesembs, less intervention is sometimes better than more.

They're plants that reward observation.

Before watering, ask:

What species is this?

What season is it in?

Is it actively growing?

What is happening with the leaves?

How quickly is my soil drying?

What has the weather been doing?

Is the plant getting enough light?

Those questions are much more useful than simply following a weekly watering schedule.

There Isn't One "Mesemb Care Schedule"

This is worth emphasizing.

A Lithops growing in Minneapolis under artificial lights isn't experiencing the same conditions as a Conophytum growing outdoors in South Africa.

Even two people growing the same species can have completely different watering requirements.

Pot size, soil composition, temperature, humidity, light intensity, airflow, and the plant's growth cycle all matter.

That's why you'll find seemingly contradictory advice about mesemb care.

One grower says:

"Water every week."

Another says:

"Don't water for months."

Both could potentially be correct for their particular plants and growing conditions.

The goal isn't to find a magic watering schedule.

The goal is to learn what your plant is doing.

Mesembs Become Easier Once You Stop Treating Them Like Typical Succulents

This is probably the biggest lesson.

Mesembs aren't necessarily difficult because they're delicate.

They're difficult because they have evolved around a very specific relationship with water, light, temperature, and seasonality.

Once you start paying attention to those things, they become much easier to understand.

Instead of asking:

"When should I water my mesemb?"

Start asking:

"What is my mesemb doing right now?"

Is it growing?

Is it preparing for dormancy?

Is it replacing old leaves?

Is it flowering?

Is it actively using water?

Is it sitting in conditions where the soil is drying quickly?

Those questions will get you much closer to successful cultivation.

The Reward Is Worth the Learning Curve

There are plenty of plants that are easier to grow.

But few plants are as weird, fascinating, and rewarding as mesembs.

A healthy Lithops can look like a handful of colorful stones.

A mature Conophytum can produce an incredible flower from a plant barely larger than your thumbnail.

And once you start looking at the enormous diversity within the group, it's very easy to fall down the rabbit hole.

That's part of the fun.

Mesembs aren't plants you simply water once a week and forget about.

They're plants that teach you to pay attention.

And once you learn to read them, what initially seemed difficult starts to make a lot more sense.

Growing Mesembs at Home

If you're just getting started, don't feel like you need to collect twenty different species immediately.

Start with one or two plants.

Learn their seasonal cycle.

Pay attention to how quickly their soil dries.

Watch what happens to their leaves.

Give them as much light as you can reasonably provide.

And resist the urge to water simply because they look a little different than they did yesterday.

With mesembs, observation is one of your most important growing tools.

About PHK Ceramics

At PHK Ceramics, I am fascinated by plants that don't look like ordinary houseplants—and mesembs definitely qualify.

I make handmade ceramic pots designed with unusual plants, cacti, succulents, and caudiciforms in mind. If you're growing plants that appreciate excellent drainage and a carefully chosen container, the pot is an important part of the growing setup.

Explore more cactus and succulent growing guides in the PHK Ceramics Journal, or take a look at our handmade pots for your next unusual plant.