Hello, I've had this cactus for 2 years. No idea what kind of cactus it is. It has always had a tan color along the base of the whole plant. It has always grown steady, but started to grow sideways instead of straight up, so I trimmed off a lot of the plant.
When I put the plant back outside for the Spring and Summer it started growing like crazy. I don't know the technical term, but there are little, purple buds sprouting out everywhere. It looks very cool. Is the tan color at the base a concern? I don't want this plant to take off, just to die from unhealthy roots or some other ailment.

That is not a cactus but a Euphorbia, I think E. resinifera, which is a Moroccan plant... very dangerous sap, handle with care. These plants can grow quite large in nature and in the landscape. They form mounding clumps like this:



I suspect the plant has responded to your pruning by branching heavily. The brown areas at the base look like normal aging to me. I would move the plant up a pot size unless space is limiting. If you really want to reduce the size of your plant, you can start a new one from a cutting. Again, very dangerous sap, wear gloves and eye protection.

If corking, it should be hard. If solf, you got trouble and cutting and restarting is best. Also to reduce corking, I grow mine in more shade. If your plant got sunburned, the increase corking. When plants age, it is natural to cork or turn to wood.
Stush
Good advise Baja

It does not look like natural corking to me.
When a Euphorbia forms cork 'bark' it is usually from the bottom up.
Your brown is skipping around with green between the brown spots.
The brown areas look shrunken. Corking does not do that.
I believe it is a fungus. I see concentric lines behind the leading edge of the brown .
These could be signs of anthracnose.
You should cut off the damaged parts and make new starts from the clean growing tips.
Be sure to throw away the dirt they were grown in. Do not put into your compost.
Throw away the pots or soak them in Bleach.
Sterilize your cutting tool after use.
Copper or sulfur spray is possible to use as a protectant, not a cure.

Perhaps some photos will help illustrate.

Normal behavior for E. resinifera is for older parts of stems to turn brown. Typically this is covered up by new branching as the plants age and the mound expands. In my experience it starts on the side that faces the afternoon sun and spreads around the plant. Nothing I would ever have the slightest concern about. Life in day-long sun is not that easy but these plants are extremely durable, and as long as they keep growing, the brown parts are covered up by green parts. Does that make sense?

On the first plant you can see the transition happening. The plant was mostly a long main stem with a few side branches when it went into the ground. The main stem is where the browning started. Almost all the branches from the bottom grew after it went into the ground about six years ago. These plants transform into monsters when they leave container life, given enough time.

On the second plant (which has been in the ground for longer and is a second clone) there are also brown parts like that, but they are hidden below new growth and I'm unable to climb up and get the perfect shot. There are some scary plants growing back there.

Here is my Euphorbia resinifera. I think the corking on Stelios369's plant is just that - corking. I can't remember how long I've had this but it's been a few years - maybe 20 or 25. It has spent most of its life in a pot.


Daisy

Thank you for your responses! I had no idea it wasn't a cactus, nor did I know the white sap/milk was toxic. The whole bottom of the plant is tan but not soft at all. I trimmed off a few portions of the plant and it started growing like crazy everywhere else. I've had for 2 years. It's grown slowly until recently, and now it's taking off.

Hello Stelios369, I do agree, that it is corking. Have seen that in some of my cacti and euphorbias. Sometimes environmental factors influence corking, like if the Euphorbia was still dormant and got too wet and humid, it will do that. But once it has been kept dry and warm, that damaged part will slowly dry out, harden, and heal. If it was facing the sun as it dries out, all the more it tans.

Glad to see it is corking, so it has healed and recovered. The blemish stays, I just call it their battle wounds. My Euphorbias are also awake now from its slumber, active growth ensuring. If you intend to repot, heed the advice to handle cautiouslly, since it is a toxic plant.

I find my Euphorbias love warm to hot temps, gets quite thirsty, so I can give them more water but got to keep the media very well draining, making it gritty helps protect the base part of the plant from moisture damage.

What is the typical cycle for this plant? Grows in the summer and sleeps in the winter?
I would love to re-pot this plant, however, it's not worth the punishment this plant can dish out. Perhaps I need a friend to help balance the plant while I deal with swapping the pots. I hate it when the bundle of roots are too wet and fall apart. That's when I make 2 plants from one, or convince myself I never liked the plant anyway.
My plant gets lots of sun and water in the summer. What's too much sun in the summer? Does it like the same soil as cacti?

The plant is opportunistic and will grow any time of year when the conditions are right. If you are having problems with wet roots during repotting, wait until the soil is dry before you repot. Normally I wait until the soil is mostly dry before repotting anything. Doing this also helps serve as a way to independently confirm my guesswork regarding how fast the soil is drying out. I would use regular potting soil cut with about 50% pumice, which is the same thing I would use for cacti.

There is no such thing as too much summer sun for this plant in a mild climate. What are conditions like where you are?

They grow actively during summer, the warmer it gets, the happier it is. so it can take good watering. I use cactus soil but I really make it very gritty adding in more pumice or top dressing it with chicken grit, so the base of the plant will not be too soggy. During winter time, I bring them indoors keeping them dry. Our winters have more rain, so as with most succulents, got to keep it dry during that period.

Summer conditions and sun intensity varies from place to place. We got strong sun here, so it does help it endure our triple digit heat with some shade from our city trees.

Our winters are also wet but quite mild, and I find these plants are most active here during that period (one reason why I stressed their opportunism).

Winter mildness does vary too..once it starts hitting 30F and below, most of the succulents really hate it. Wet and cold tandem, never a good combination for the succulents.

Best to really know if there are frost warnigns or hard freeze warnings during winter, so the plant can be moved as needed.

That sounds like prudent advice.

When you're wondering what the seasonal cycle might be for a certain plant (like Stelios was asking, and a question I find kind of fascinating) you have to look first at the climate where the succulent is from. If it is going to have any preference, it will almost certainly grow during the wet season in habitat and be dormant/less active during the dry season. For example, Aeoniums come from a Mediterranean climate with wet winters and dry summers, and they will naturally prefer activity in winter and rest in summer, regardless of how much water they might get in their new homes.

In the case of the Euphorbias, you're looking at a widespread family from all corners of the globe, so there's no way to generalize. A plant from the winter rainfall area of South Africa may rest in the summer, like our native E. misera. But a lot of tropical Euphorbias (from Madagascar or West Africa for example) like it warm and wet, no surprise there, and they often obey a pretty strict dormancy during the off season, regardless of how kind the conditions might be. In almost all other cases, these plants are opportunistic in my experience, meaning they are not strict about the timing of their cycle of activity and rest. Here, where the climate is forgiving... you can't really ask that question in areas with cold.

For what it's worth, Euphorbia resinifera is from a Mediterranean climate area in Morocco (most rain falls in the winter). Here in a climate not too different in that respect, I suspect their behavior matches what you might see in habitat. The main difference is they do actually get a little rain in summer, and we get none.

I chopped off a large portion of the plant, so there are no more soft spots. However, it looks really unbalanced. Oh well! Surprisingly, it had another growth spurt.
Do you think the tan portions at the bottom pose a risk to the plant in the future? If I cut them all off there would be no more plant. Although I did plant 3 cuttings (being careful of the toxic milk) and they're already growing.
Here a few new photos.

Your plant is happy with your care and has responded well.
All of that new growth looks great.
Evidently it was natural corking and not a fungus.
As a fungus would have kept rotting even after the surgery.
and you say the cuttings are growing too.
well done

I think it's kinda' funny how there is so much knowledge out there about some of the most mundane things. Even funnier, the most knowledgeable response will probably come from some tax lawyer with a hobby, and not a botanist or landscaper. Thank you for all your help!

This same plant is giving me trouble again. Every month or so, one portion ( a branch? A frond? What do u call them?) of my plant goes soft and rots. Therefore I need to cut it off. 85% of the plant is healthy, but I repeatedly need to cut off sections. So, I cut this plant down to a skeleton. It looks ridiculous but it's coming inside for the winter, so who cares?The rotting part went below the soil, so I took the plant out of the soil to make sure there were no soft spots on the center (or trunk?) of the plant. It was colored tan but very firm. I re-potted it in a new pot and high-drainage soil.

I live near Baltimore, Maryland. Summers are hot and humid, and winters are cold as hell! Last year I randomly placed this plant in my garage for the winter. I never thought it would survive! I have 2 cats that love to chew on plants and knock them over, so I couldn't bring it inside. I watered it once every 3-4 weeks, and it was fine. Again, my garage is the only option for this plant during the winter. Any tips to help it survive? The garage is not heated, but stays about 20-30 degrees warmer than outside. Should I give it a blanket? Water it with warm water?

Every year I get suckered into buying orchids from the grocery store, or Home Depot. I've killed almost every one. Now that I've finally been able to keep an orchid alive for multiple seasons, I need a new challenge. Keeping this Moroccan "spawn of Satan " alive is it. My goal is to have it looking green and lush by next summer. Here are pics with one of the clipping growing like crazy. Thanks!

My sense is: it has been way too wet. The soil in the original pot looks like it would probably stay moist very long especially in a humid environment. This plant naturally occurs in an area of very low to non-existent rainfall, and super low humidity. The fact that it keeps growing, but also coming up with sections that rot, means you are probably not that far off, but a little too far towards the wet side of the scale.

So getting it in better draining soil is a great first step, water only when the soil is completely dry (any time of year) and on top of that very sparingly in the winter. I do not perceive this plant as particularly tender, but then we do not get much of winter here in the low desert of Arizona, not sure how much light it gets in the garage, but if it gets some decent light and the temperature stays above freezing it is probably OK for the winter, just do not over water it.

One thing I can say regarding growing this plant here in Arizona is that it gets by on minimal water in all day full sun, in pretty poor soil - mine and the neighbor's are just planted in the local top soil which is very loamy and does not drain very well, but despite that it rarely remains very wet for more than a few days in a row - and thrives.

I think your best advise is to trade or sell this plant. I had to do the same thing with some of my larger plants. Too hard and too much to winter them over.
You are wise to keep this plant from your cat. As advised above, the sap is very toxic and can cause blindness if it gets in the eyes. Cats can scratch the base (which they like to do) getting sap on their paws then wipe their eyes or worse, come to you for pets and you wipe your eyes! Causes skin rashes as well.
I wash it off with shampoo. Seems to work the best.
If keeping, can you put some form of lights on it about 12 hrs. / day? Gives some warmth and will add to the elect. bill. A enclosed box with a light built in. Also when cold out, no water. Water lightly only when it gets a warm day or two.

This plant is a pretty tough survivor of extreme exposure and neglect here. The fastest way to kill it is to give too much attention, esp. during the colder months. The ones here sort of crawl along (no fast growth during any season) and they get only occasional water (say every 2 weeks in the ground) during even their most active period. If your potted plant is repeatedly going soft then you are probably watering too often or the mix does not drain fast enough. Ideally wait until the soil goes dry or nearly dry at depth during the growing season, and then back way off on the water during the garage season, like you have been doing. The actual time interval between watering during active growth will depend on the conditions (temp, exposure, air flow) but it might be in the range of 1-2 weeks depending on the size of the pot.

I would say you are lucky if the rot events are only taking individual branches and not the whole plant. They are warning signs that (like Thijs said) things are too wet, and your plant should be fine if you make a few adjustments.