Winter damage update (March 2026)

I’ve been dragging my feet on this, but the time has finally come to address the elephant in the room. The winter of 2025–2026 has been like no other I can remember. We got down to freezing maybe a couple of times, for a few hours near sunrise, but that was it. Some mild frost, but no serious freeze. And we haven’t had excessive amounts of rain either. As a result, we shouldn’t have had much, if any, damage in the garden. And yet look at this:

Agave potatorum ‘Cherry Swizzle’ rotting in the center

As you can see below, there are plenty more examples of rotting agaves.

I had barely brought home this variegated Agave attenuata when it started to fall apart:

Variegated Agave attenuata

Mangave ‘Bloodspot’ × Agave parrasana:

Mangave ‘Bloodspot’ × Agave parrasana

This Agave impressa was one of my favorites. This really hurts:

Agave impressa

And it is a complete loss. There is no coming back from this:

Agave impressa

This variegated Agave victoriae-reginae is a goner:

Variegated Agave victoriae-reginae

The biggest surprise of all was the shocking damage on several Agave victoriae-reginae:

Agave victoriae-reginae #1 and 2

Agave victoriae-reginae is one of the hardiest species, according to the San Marcos Growers website tolerating temperatures as low as 10°F, so this damage is not caused by the cold. Plus, it’s been through far wetter winters, so it’s not that either. At the end of this post I’ll share what I think was the cause.

Agave victoriae-reginae #2

Specimens #1 and 2 above look they will live. The rotten (and now desiccated) leaves will eventually be shed.

Specimen #3 below won’t make it, I’m afraid. The rot has progressed too far towards the center. This agave species grows very slowly; I estimate even the smallest of the three (the one below) to be 10 years old. That makes the loss even more painful.

Agave victoriae-reginae #3

The lower leaves on Agave mitis var. albidior below look pretty bad, but the rot appears to have stopped before it got too close to the center:

Agave mitis var. albidior

I’m fairly confident it will live.

Agave mitis var. albidior

Likewise, I’m cautiously optimistic that this Agave margaritae will make it:

Agave margaritae

Unfortunately, the cacti in the next three photos have kicked the bucket:

Echinopsis chamaecereus hybrid

Lobivia acanthoplegma var. roseiflora

This golden barrel (Echinocactus grusonii)...

...split open like an overripe durian fruit, and smelled like one, too

In general, aloes fared significantly better than agaves, but I lost this one:

Aloe deltoideodanta ‘Sparkler’ progressed quickly from the rot you see above to total mush

Aloe fosteri looks bad, but the rot has stopped, and the very center seems tight. I give it a 50:50 chance.

A few more random losses:

Cheiridopsis denticulata

Hechtia michoacana

Hechtia lanata

As promised, here is my theory why the winter of 2025–2026 has been particularly brutal for Sacramento area succulent gardeners:

The Central Valley was trapped under an unrelenting blanket of Tule fog that lasted for weeks at a time. This specific combination of factors created a perfect storm for succulent death, turning normally bulletproof plants into mush.

The Tule fog this year was driven by heavy rains in the fall of 2025, which saturated the soil. When a high-pressure system settled over the state, it acted like a lid, trapping a thin layer of cold, moist air against the valley floor. While the Sierra foothills and Southern California saw record-breaking warmth, Sacramento stayed socked in. This prevented the ground from warming up, keeping succulent roots in a cold-soak state for an extended period of time. Without any wind to break the inversion, there was zero air circulation. This is significant, because for succulents, airflow is the primary defense against the buildup of moisture on leaf surfaces.

Succulents are remarkably resilient to dry cold, but they have almost no natural defense against sustained wet cold. Succulents breathe through stomata. In 90%+ humidity with no sunshine, the plant cannot transpire. Water stays trapped inside the fleshy leaves, increasing internal pressure until cell walls begin to burst, which then becomes an entry point for opportunistic fungi.

Sunlight provides natural UV radiation that kills many surface-level fungal spores. Without sunshine for weeks, fungal pathogens like Anthracnose were able to colonize plants without any environmental resistance.

Agaves were particularly hard hit. Their rosette shape, where new leaves emerge from a central cone, creates a natural funnel. Moisture from the fog condensed on the leaves and trickled down into the crown. Because there was no wind or sun to dry out this “cup,” the moisture sat against the sensitive growing point, leading to bacterial and fungal crown rot — a death sentence.

There you have it, a layman’s speculation, based on a bit of research and personal experience.

Beyond these fungal issues, I had a different kind of damage to contend with on some of my dudleyas:

Example #1

Example #2

When I first saw these nibble marks, I immediately thought of rats. They are my go-to culprit for a lot of things, and often I’m right on the money.

This time, though, it wasn’t rats. At least not the nocturnal kind with long hairless tails. It was daytime rats with bushy tails, aka squirrels. This guy, to be precise:

I caught him red-handed, and he was shameless:

It might be the same one I caught eating my echeverias in November.

There’s no way for me to keep the squirrels out of the yard — not even Stella is enough of a deterrent — so the only thing I could think of was to place a couple of mouse traps in the dudleya bowl:

And it seems to be working. I occasionally find the traps on the ground, so they do get triggered. Fortunately, no squirrel has been injured so far; the last thing I want is to deal with a critter caught in the trap.

After all this talk of death and destruction, I want to end on a positive note. Take a look at this variegated cow’s horn agave (Agave bovicornuta ‘Holstein’) in the backyard. It’s never looked this beautiful:

Agave bovicornuta ‘Holstein’

© Gerhard Bock, 2026. All rights reserved. To receive all new posts by email, please subscribe here.