The stems don't look discolored like I'd expect them to be if rotten. Have you tried cutting the stem at the shriveled part and looking inside for the discoloration typically caused by rot? The shriveled stem on the left in the pic looks more like something that died because it couldn't handle the conditions than the two on the right. I have seen stems fail because conditions aren't good for the plant while the end of the stem stays OK. I don't grow these outside all year so I'm not sure. However, the stems don't look like they've rotted because of a pathogen. I'd guess they collapsed because of poor conditions for the plant.

I cut the two on the right at the folded stems and you are right there is no sign of rot. The one on the left does look rotten, but I am thinking it may have died for other reasons first and then the rot was opportunistic.

I put a wood skewer about 18 inches down into the gritty mix soil for a few hours. That came out slightly moist, not wet.

Would you guess the plants are getting too much water or too little?

The gritty is damp? Overwatering. I have Aeonium in a vacant lot next door with Southwestern exposure with 1' of sand over bedrock here in LA. They get watered once a year on the 4th of July. And that's just insurance for fireworks.

Westes, what have the temps been like for you this Summer?

I don’t grow these but it seems like recall reading that they don’t do well in the heat...? Does that sound familiar to anyone?

They do fine in heat as long as they are dry.

Definitely familiar Stewart, they shut down in strong heat. Here in NYC (indoors), my Aeoniums closed up their heads, 'til the weather cooled down. I find they didn't do well indoors so I quit growing them, but I know for a fact, they do poorly in the heat.

Cactus McHarris, if you're out there, pls remind us how yours dealt w/ the heat in San Diego. I recall yours all looked so nice, but don't recall them shutting down like that.

Were they exposed to any frost last winter?

They tolerate heat just fine.....they are native to places that develop considerable heat....Canary Islands, North Africa. But are best protected from full sun in summer and with minimal watering (summer dormant).

Folks are able to grow them successfully outdoors in Phoenix, AZ and that is hotter in summer than even their native origins!!

@socal_stewart we had a moderate summer, usually daily high under 90F.

My Aeoniums with direct sun exposure shrivel to nothing during Summer. I do not think they tolerate this well. These particular plants have partial shade as they are tucked into the corner of a hedge.

Andrew, these aeoniums did amazingly well in Winter. See the photo below. You wouldn't even believe it is the same pot now.

@gardengal48 minimal water means once a week? once a month? Would it be okay to put the three-times-a-week schedule on a minimal drip?

I would never put containerized succulents on a regulated drip system. Or even keep to any sort of schedule. I would only water them by hand as necessary. In summer, aeoniums need only enough water to keep the foliage turgid.

FWIW, I water mine maybe once a week.....sometimes not even that often.

Westes, what a shame. They were so beautiful. We’re they in direct sun or did they have some shade...?

I’m trying to understand the varying advice given here with regard to heat & sun together with the before and after photos of your plants.

Something isn’t adding up.

The mistake people make with Aeoniums is trying to keep them looking good like they were in the winter through the summer.

Here are some of my Aeoniums right now.

This is a partially shaded 'Cyclops'. During the winter you can't see a single stem it's so full.

Here's an A. haworthii that hasn't been watered since the 4th of July in full sun and we've had some pretty hot days. It looks rough but it will perk right up when the rains start.

Here's 'Voodoo'. They are in full sun with no irrigation since the 4th. Those rosettes will be 24" in diameter this winter.

@gardengal48 (PNW Z8/9)

Just a comment.

In your post, you say " they are native to places that develop considerable heat....Canary Islands, North Africa ".

The Canaries, are located some 60 miles out in the Atlantic. Although at a Latitude similar to the Sahara, this separation emeliorates it such that the climate is more Mediterranean, with highs of 30C (86F) with rainfall, being, during the summer months (May-Aug), generally non-existent.

I'm guessing that these conditions aren't that different from the OP's.

Fof

It's not so much the heat that is of issue - although aeoniums are able to grow in some very hot climates with just a small amount of sun protection - but rather the watering. Compare this part of your statement: "with rainfall, being, during the summer months (May-Aug), generally non-existent" with the OP's query of "Would it be okay to put the three-times-a-week schedule on a minimal drip?" and the question kind of answers itself.

@gardengal48 (PNW Z8/9)

Agree 100%. My comment was basically just to say that the Islands, themselves, are not that hot.

Apologies for any misunderstanding.

Fof

Record highs in the Canaries are around 110f. That's pretty hot.

Karen, thanks, I think the above comments answer the questions about watering and when quite well, but a few cents anyway:

Plants in pots and plants in the ground react to non-seasonal water differently. My planted-in-ground (PIG'd) Aeoniums got some summer water, because they were growing with other plants that didn't mind an irregular watering then, but the potted Aeoniums (only a few) were pretty much kept dry in summer.

There is at least one species (A. smithii) that tolerates no summer water, but the others don't mind it once in a while. OTOH, when they get that dessicated look, it's visually appealing (to me, anyway).

Yes, watering that often will definitely lead almost any species to an early grave even if it is in their winter growing season.

As far as the Canaries, it's a Mediterranean climate, but many (most?) of the Aeoniums that hail from there do so in places of volcanic soil.

Still my favourite after all these years (photo taken from the WWW). Aeonium (arboreum v.) rubrolineatum

I was thinking along the same lines as cactusmcharris. Perhaps keeping them in a pot makes a difference in their heat tolerance.

@socal stewart they are in partial sun with a pretty large hedge around them to shade them much of the day

@gardengal48 I was only asking a question about how often to water the plants. I never said I was watering them three times a week.

If I do not put them on automatic drip, then they can sometimes go three weeks without water, so I am going to hurt them either way.

Do I want the soil at the roots level to go completely dry between waterings?

Strangely, in my growing conditions Aeoniums don’t have problems with over-watering. My plants are outside being watered by rain, and we get LOTS of rain here. And I’ve never seen root rot in my Aeoniums.

The issue with the plants in your photo seems to be in the stems. Do you dig up the affected plants to check the roots?

As you observed, aeoniums are winter growing plants from a Mediterranean climate, same as you have in California. They do shut down in summer but they can also tolerate some watering although they get stem rot very easily. I live in a hot summer rainfall climate and the aeoniums go under a tree in summer and this helps them tolerate the rain. I watch out for stem rot and if I notice it, I cut the stems and reroot them

Nik

what do you think causes the rot to get into the stem during hot summer? Surely it can’t be related to wetness of the soil. Perhaps severely sunburnt tissue let’s it in?

(edit - which I’ve just realised takes us full circle to the question asked by westes in the first post! - but unlessed I’ve missed it, has remained unanswered)

I think it's edema that causes the stem rot.

Like an umbrella about to open, Bill. Compressed and appressed circular goodness right there.

@cactusmcharris, interior BC Z4/5 You mentioned Aeonium Arboreum var Rubroblineatum. Every photo of this I find online looks different. Annie's Annuals shows it online but that photo again looks totally different and also has thick stems. They talk about it growing to five feet (!!). Does this look like the right plant? Do you know where I can buy it in the US?

If the Annie's Annuals page is actually a different species, can someone identify it?

Okay, to try to bring this thread back to the original topic, I want to propose a theory, and people can tell me if I am wrong. I think the Aeoniums in the original photo started to die of dehydration - simple underwatering - even though it was in the Summer and Aeoniums are dormant at that time.

Here is the question to answer first: when Aeoniums are allowed to dry out, how do they present at death? Do they bend over mid-stem, which I think is the key aspect of what happened to mine. My plants had no rot at the root. There was also not progressive disease. In other words, the rot did not spread. Instead, the plant simply got soft mid-stem and collapsed at the soft section. There is a good chance the plants were underwatered. The gritty mix soil had become compacted with a lot of micro roots, and the watering was on automatic drip. I am suspecting the amount of moisture delivered never penetrated into the gritty mix sufficiently well, and for such a large pot what they needed was a drenching with water ever two or three weeks, that would have penetrated the soil.

Is this theory a possibility?

I finally got around to digging out this container and discovered that the drain hole was mostly blocked by roots climbing out the pot. Having said that, I still think my plants died of dehydration, but poor drainage at the bottom might have contributed to the situation for those plants with deep roots. Basically, the container was long overdue for replanting, and I should have acted faster when I saw the first plants start to develop weak mid-stems.

I have concluded that Aeoniums are really not a dormant plant in the Summer. What they are is adverse to high amounts of direct sun. If you keep them in the shade they appear to do quite well in the Summer months. I have moved all my remaining Aeoniums into the shade, and every variety so far is thriving and in full bloom, being watered on a regular schedule and showing no signs of dormancy. Every single one of these containers looked horrible when left in the full sun. When moved into nearly full shade, they quickly recover and then restart growth.

This spring I closed my greenhouse for a cold night and left the greenhouse closed too long in the morning. The temperature was too high for too long. An assortment of my plants developed collapsed stems. Sometimes the stem collapse happened just above the level of the potting mix. After seeing this happen to a range of different plants all at once it seems that stem collapse without obvious rot is the result of exceeding the tolerances of the plant, at least for some kinds of plants.

@Polypompholyx I was having a problem with an automatic drip system not sufficiently penetrating down into the gritty mix. So my theory is the roots stayed bone dry for quite a few months, and at some point, the plant's tolerances were exceeded.

An almost instant stem collapse generally has some kind of fungal or bacterial rot involved. Aenioms that die of dehydration will develop smaller, fewer leaves, they dont normally wilt. Greenhouses easily produce the kind of humidity that promotes rot. Sunburn causes white patches, not wilting of stems. Aeoniums grown outside always have fibrous stems that can rot but never wilt although as you have noticed they grow all year round if kept in shadier conditions when it's hot, that's my experience too in a summer rainfall climate

@niksouthafrica Then how do you explain the result that @Polypompholyx is reporting, where he had a mid-stem collapse in just one day? Apparently a mid-stem collapse can have other causes than just fungal/bacterial?

My Aeoniums did develop smaller and fewer leaves before the mid-stem collapse. And it may well be that they were so weakened by dehydration that some opportunistic fungus started on them mid-stem. The whole thing is perplexing to me. They went from vibrant to devastated in just a year.

many rots are not apparent until the collapse happens. I can assure you, it isn't wilting. I have had this happen with plants grown outdoors, most recently, some sanseveria outside fell over. I'm pretty sure that they took strain in the extremely cold nights we had a few weeks ago. Once they had fallen, I saw that there had been some rot that wasn't apparent. Whenever a euphorbia falls over, I know there's rot. This happens when the ambient humidity becomes too high in summer, even though I'm not leaving the plants in the rain or watering them

@niksouthafrica We had no freeze, and we have no real humidity in our Summers. SF Bay Area has a Mediterranean climate. What I did have is a failure to understand the hydration characteristics of the soil, and my drip system was inadequate. So the plants did not receive enough water. They did shrivel up. And then they collapsed mid stem. It might be that in the weakened state they succumbed mid-stem to some rot, but this was not the real cause of death.