The cold damp early morning air is most likely the culprit. Euphorbias really need to be protected from the cold. I would suggest bringing this guy inside a warm heated dry house, put next to a sunny window, and hope those spots don't spread. If it does you know what you gotta do;).

This was the same plant that I said took 6 months for my cuttings to root.

@Kara so what are these spots? That is dead tissue from the cold, not a fungal infection?

How much water can these tolerate during a cold winter? I can probably bring this into a sheltered porch area, but there is no room inside for it. At least I could make sure they don't get much water during the winter, assuming that is a problem for them.

So these spots are all continuing to spread.

Note that there are two different types of spots. The light brown color is sparse and spread across multiple parts of multiple plants. There are also black spots, and those are grouped together in the middle bottom section of the middle plant in the photo.

Honestly reading about this online has been confusing and not helpful. Some people say it is due to too much sun. But these spots always seem to happen to people in the Winter, so that seems wrong. Mine started in Winter too.

Some people say the spots are due to the cold, and we are getting down to 40F each night. But this plant is supposed to survive to 30F for brief periods, so that seems like a stretch as well.

Some people say the spots are due to overwatering. Except I am not watering. There have been rain days and those are what may have started this, but one guy online says he has never seen a Euphorbia Lactea die in rain, down to even 30F, as long as the soil is well draining. I planted in gritty mix.

I did test the soil moisture, and down deep there is still a lot of moisture in the pot, so the turface is holding water in these cold temperatures for a long time. But, again, I am not watering. So root rot seems unlikely.

I cannot bring the plants inside. There is no room for them. I could put them into the shade of a porch area, which will keep rain off of them the whole winter, and it would also reduce the amount of sun they get. Is that what I should do, given that I cannot bring them inside?

I am not sure at this point should I be trying surgery on these plants? There are so many spots it seems almost pointless.

My experience is this has never happened in the warmer months always the cooler months. I lost my Euphorbia Trigona rubra from the same thing that is happening to yours. I just threw it away there was not enough on the plant to save. My Euphorbia lactea 'White Ghost' I began to see the same issues so I chopped. I see parts on yours you could definitely save.

If you don't cut this will just spread like wildfire. It honestly does look like fungus, but it hasn't been all that wet, and only happens during in the cold.

My Firestick will get a similar thing and if I don't cut the bad parts off it will just spread all the way down:(.

The only way to save your plant is to cut. The cuttings you will definitely have to keep inside.

Do you cover your non cold hardy succulents at night with frost cloth;)?

@Kara no I have not used frost cloth yet.

Should I be using a melon scoop to take out the areas with spots, and just leave behind a sore that oozes latex / sap? I guess I need to dip that into water+clorox between uses? If you have a tool you like for these cases please point me to it.

I snapped off one of the limbs and cut into the black spot area. This doesn't look like a systemic infection that is in the core of the plant. This looks like something at the surface. It's more like a burn?

I've never used a melon scooper. I guess that could work if sharp enough. Just keep everything clean;). You can sprinkle a little dusting of cinnamon on the cuts. Acts as a natural fungicide. I've never used it.

Do you have a garage or somewhere you can keeep this guy a little warmer and dry while the cuts scab over?

Time to get frost cloth or old sheets. I personally like frost cloth more than sheets because the material is hydrophobic. The water beads off. Eventually they will get sopping wet if left out in the rain, but will totally repel morning dew. I saw a bunch at Home Depot and I believe they were on sale;). It's just like tucking your plants to bed at night;).

Dec-Jan is when I use these cloths the most. Just at night cover and in the morning uncover. Sounds like a lot, but it really isn't.

Those spots are most likely frost damage.

So given it is frost bite do I still need surgery?

The middle plant I would lop off the top, right where I made the first line. Then the second line slice right under all the dots. Always cut at a slant so water won't be able to pool.

Now you've cut out the cluster of dots;). I put a line on the left little branch. I see that branch has black dots. I would just cut that part off. Wouldn't waste my time;). There is frost damage at the base of this guy. Not sure what I would do with this part. You could try to melon scoop the part out or use a sharp paring knife. There is lots of branching at the base so you should really try to save this part:).

The one on the right you can either cut at a slant where I've made the line. That would be the easiest or try to cut out those bad parts I've marked up, but honestly I would just slice that piece off;). The bottom two branches I've put a square around or a line cut those pieces off. The part I've circled next to the wooden skewer you could try using the melon scooper on this part.

The little parts I've circled below just keep a close eye. I have had areas like that stop, but this Euphorbia needs to be kept warmer for that to happen.

@Kara and you think that frost bite like this will consume the whole plant if I do nothing? It becomes like a fungal infection that is just in the skin of the plant?

Yes I do think it will take over the plant. It's like rot. I mean you've noticed it getting worse and it hasn't even been that long. There will be areas where the damage will stop and that Area will survive, but the Euphorbia will be a shadow of its former self. The frost damaged or rotten parts remind of when you cut into a bad melon.

Every spring I have to cut off pieces of my Firestick that has frost damage. If I don't the rot just spreads. If I were to leave the frost damaged parts my plant would loose a bunch of size and look like crap.

These white ghosts are really temperamental succulents! I see enough people online reporting the exact same situation as I am to believe that they are really indoor plants or belong in zone 10+. They really do not tolerate 40F temperatures of a California 9b zone winter in a robust way. It really is surprising to me. They look like they should be hardier than that.

It is really interesting that 90% of these spots are accumulating on the side of the plant that faces the sun! So it is apparently something to do about getting direct sun together with a cold air environment.

I've had mine for approx a year. I've always kept it outside but it never gets direct sunlight. Just bright light.

Even here in sunny San Diego we get some nights down in the 40's. We've had several over the last few weeks. Depending on what part of the County, it can get colder than that. We are full of mini climate areas so it really depends on where you are. Probably the one consistent thing countywide is the extremely dry air.

I perform a cursory inspection when I can during the week, but since I leave for work and get back home in the dark a more thorough inspection has to wait until the weekend. So far, I haven't seen any signs of frost damage, but I'll keep an eye out. Possibly the difference is that I'm in a more arid climate? The days have been mostly in the 70's, but the air has been extremely dry both day and night.

I haven't found they're care particularly difficult, but maybe I've just been lucky. I had a lot of pretty hot pink growing points this year. Some of those did not gradually fade to the typical greenish white. I did notice near the end of the Summer they seemed to have turned a light tannish pink color. That was way before it got cold though so I didn't take it as any kind of frost damage since there was no frost. I'll try to post some pics when I can.

Tyler

@Stewart It could be some humidity issue, but the average humidity here in the San Francisco Bay Area during winter is around 40%, so it is not particularly high.

If you search online there are quite a few people who have these same symptoms, and they don't seem to be committing obvious mistakes like overwatering in a peat moss soil. It just looks like the plant does not tolerate many environments.

Here are some pics I took this morning. The pinkish tan coloring has been there since late Summer - early Fall. They don't seem to be changing at all.

Tyler

I am updating this thread on progress of these euphorbias. The clue to what was happening here was when I looked on the back side of the "infected" plants, which is the side hidden from the sun. It was completely CLEAN of any discoloration. The brown markings are only appearing on the sun-exposed side of the plant.

It turns out that these brown spots are more like blisters of some kind, and as seen in the photo below they are starting to scab off the plant. I'm not clear on why this plant would get sun blisters during Winter but not during Summer. This is a kind of albino plant so probably there is an unusual light sensitivity there.

I did lose the plant in the left part of the original photo, to root rot. That was a clear case where the various parts of the Euphorbia became mushy. I really don't know why it happened. That plant never took good root the way the others have. So apparently it wanted to be planted earlier in the Summer to get a chance to grow roots and get strong.

Also, if the plant was bruised in any way, this can cause an unexplained decline and death.

I'm glad you've figured it out and they've improved.

@laticuda so you are saying that a bruise can turn into root rot? How would I have likely bruised this? They other two were staked so they had an easy time setting roots. The plant I lost had no stake. I wonder if that made any difference?

I wasn't sure if you had them shipped to you (but for some reason I thought you did even though reading your post again I don't see an indication of this). I received a cutting that got bruised in shipping and it still has the scar and took a REALLY long time to form roots, even though the bruised part wasn't below the soil level. I suspect the stress of the physical injury also affected the speed at which it wanted to make roots.

Physical damage that isn't allowed to callous over before being exposed to moisture will rot the plant. This is why it's recommended after repotting succulents, to withhold water for several days to allow any damage to dry up.

I think staking the other two definitely helped them to form roots with some stability. The one that wasn't staked could have caused bruising from the weight of the plant wiggling and pressing against the substrate? Edit: or when it would make roots, they were easily broken by even slight movements...I did this to some jade leaves today smh *le sigh*

@andy_e wow, that's interesting. Do you think bark is a good medium for fungus/bacteria to stick around, waiting to infect a weak plant?

How do you water succulents? How do you determine when the pot is ready to water?

It doesn't make sense to me that soil/perlite would do better than gritty mix. Soil is going to have a lot more perched water which is never good for succulent roots.

How are you making gritty mix?

Westes - I suspect the bark just helped retain too much water because I was getting root rot. And I live in an area that's very dry in the summer.

Here's the problem with Al's argument: it's all based on the idea that perched water is this huge bogeyman that's killing everyone's plants. It is not. Yes it's a bit of a problem for beginners, but with a little experience, anyone can learn how not to overwater your plants. Al would have you believe that in order to solve a relatively minor problem, you have to go through this enormous ritual of collecting all these different ingredients, sifting them, rinsing them, and mixing them in a certain ratio. Beginners are the last people we should be pushing this on. Instead we should teach them how not to overpot, and how to tell when your soil has dried out. Pretty simple.

Other issues:

- One of Al's big selling points is the air spaces in gritty mix. But a good organic mix (I use 50/50 potting soil and perlite) will have plenty of air circulation. And when I unpotted some of my gritty mix pots, the mix was pretty compact (and I screen out the small bits).

- It's difficult to know when it's the right time to water gritty mix, because it's so heavy. Organic mixes are so light, that you can tell by the weight of the pot if the soil is still wet.

- When gritty mix pots fall over, the mix all comes out. With robust plants in an organic mix, the root ball will hold together. Minor inconvenience, but it happens occasionally.

- For my plants that survived the move to gritty mix, it took them WAY longer to adapt and start growing then it did for plants I repotted in soil mix. And during that time, many did poorly and I could never tell if it was because they needed more water or less.

From an overall cost/benefit perspective, I haven't seen any significant benefits, AND it was a huge hassle to assemble all the ingredients, AND I lost a lot of great plants. Btw I was not coming at this as a beginner. At the time I started experimenting with gritty mix I had 15 years experience growing cacti and succulents in pots very successfully, with a collection of about 120 plants.

Andy, I'm confused as to what you mean by gritty mix. Do you mean the 5:1:1 with bark, or what AL calls his gritty mix of 1:1:1? That might help others like me who might not know which is being referred to.

@andy_e If you are an expert and know how to water your plants perfectly, even off-the-shelf commercial cactus soil will do fine for succulents. But very few people are so driven to be able to work around the problems of commercial cactus soil. That's not really a criticism of gritty mix.

What makes the gritty mix so great is that it tolerates a lot of mistakes. It is very hard to over water the plant, ONCE THE PLANT IS ESTABLISHED. In Winter, the plant can receive a lot of moisture and it still won't drown the roots.

I do second the idea that in the gritty mix it can take a long time for the plants to grow roots extensively. I have learned the hard way that you want to underwater the plants during that critical time when they are establishing roots.

If you have figured out how to water in the soil you use, I'm sure you will be fine.