This has been in the house many years. Can it live all year outside in zone 6b. As I do not want to kill it can I start a new one from a piece. I am thinking to cut a piece off the top and stick it in the ground that is what I usually do with the outside cactus I have.
I do not really know what I am doing just do what I think so advice is appreciated.

It looks to be a Euphorbia. No, won't survive outside.

Cuttings should take root easily after drying overnight.

Thanks for the name and information. I would like to take a cutting and try it outside in a pot and could get it back in before the winter. Could I just nip off a few inches off the top (its almost hitting the ceiling) and root that or should I use the arm that is growing on the left side

Definitely a Euphorbia. Possibly a trigone (African Milk Tree). I grew one as a house plant until it hit the ceiling.
It cannot handle freezing temperatures. I have grown them up to 12 feet tall outdoors.
They are very easy to root from cuttings. Be careful of the white sap. It is poisonous and a great irritant to tender skin and the eyes. The sap bleeds as soon as you cut it. You can stop the sap from flowing by rinsing the cut end with cold water. let the cutting "heal" overnight and plant in a 3 inch pot of well drained media. Do not keep it over-wet, but do not let it dry out completely.
Be certain to wash your hands with soap and water after you are done.
Since it is almost reaching the ceiling, I would cut the tallest one. These plants can support many arms, so leave the arm it has. Cut it 3 to 6 inches above the arm and it will branch with more than one new arm from the cut. Make a cutting of about one foot of the top section for starting the new plant. You can cut the middle into more pieces for plants or just throw it away. Be certain to remember the top from bottom if you are going to use the middle section for it will not grow upside down.
I can try to identify which Euphorbia, if you want to make more photos. A close up of the white pattern and the growing tip will help.
The plant needs more sun if you can give it. I turned my indoor plant, 1/4 turn every time I watered it. Euphorbias do like to be watered regularly, and will make more leaves if grown wet.
Here is my E. trigone, growing outdoors

Bob, Great information I will cut as you suggest, included another photo it looks a little thin at the bottom I am thinking to just add some soil to improve stability also will stake this for support.
Has some tan patches on lower section would this be lack of sun as I only see it house side?
Need to click on photo to see whole image.

Hmmm...Lack of sun and too much water? Its way too pale - the color should be darker green (for reference, look at Bob's photo) and the pale spots worry me.

Summer outside may be just what it needs. When I said "won't survive outside", I was talking year 'round.

Good info, Bob.

Daisy

Ed
The brown spots look more like sun burn. It might just be "corking" which is what they call bark on the lower section of succulents like cactus and Euphorbia trees.
I am more worried about the lowest section that I see. It looks skinny. It looks smaller than the
growth above. It should be brown like it is, but it should be the same size at the part above the ground.
Go ahead and make your cut and start the new plant. Grow the new cutting in the same light it is in now and move the mother plant outside to make it happy. You should get several new branches on the mother this summer. You can move the new cutting outdoors once it is established and has grown about one inch.
Bring them indoors before the first frost.

It is surprising to me that a trigona that size would not be more branchy, like Bob's. There are other Euphorbias approximately like the plant which might be a better fit. Regardless, all the above advice sounds quite reasonable to me... beheading the plant, moving it outside. The simple act of beheading should trigger branching, which is not going to work out well if you do it too high up on the plant (sort of an inverted pendulum going on there).

I have started trigonas from segments without an intact growth point and it works out just fine. So if you want to start 5 plants, go for it. Just be sure to keep the up side up.

Be careful not to rush the plant into lots of sun if it's been indoors with filtered light. This time of year direct sun is about maximum strength and that can be lethal to plants which have spent a long time in a sheltered position. So maybe over the course of a few weeks find a way to gradually increase the exposure. The problem outside is the wind will wreak havoc on a stem that long if it is not securely staked or somehow otherwise fixed in place.

These plants tend to enjoy a lot of exposure and if you want yours to grow compact and full from here on out, you will probably have better luck if the plant gets hours of daily sun (indoors through a window). Don't know what the situation is at the moment.

Plenty of good advice I think I am about ready to operate.
As I do not know a lot about gardening in general I do whatever seems to make sense
which usually works ok for me. This plant is one I do not want to screw up, its my wife's so When the top is removed can I just put it in the new soil. That is what i do with my outside Opuntia ( I am only now learning these names) and they just keep on growing.
I have been reading here about letting a plant dry and root before cutting which does have me confused as what to do.
Ed

Letting the cut scab over for a few days will help keep it from rotting. I don't think it will root unless its in contact with soil.

I never bury the cut end, just stake it up with good contact with the soil and wait for roots. Others may have had better experience than I do as most of my 'saves' are cactus that have started to rot.

If you do cut it into more than one piece, put a little arrow on the cutting with a felt tip marker to indicate up. An upside down plant will not root. I would recomment cutting it into smaller pieces as the one large piece will be harder to root and you have more chances with more pieces to get it right. Cuttings will branch at the top cut so you will end up with fuller plants.

Daisy

Good question & well said, Daisy.

There are some plants that will start to sprout roots when cut without being in contact with water or soil. That's not generally said or advised about Euphorbias, that I've seen. It is common to propagate individual leaves of some genera that way though. Echeveria, various Crassulas, and Kalanchoe come to mind.

For the Euphorbia in question the best approach is to stand the cutting up on top of the soil. If you have to bury the end a little (maybe half an inch or an inch) to keep it stable, that's fine. With the strategic use of rocks or similar you can prop the cutting up from the sides. Another thing you can do is wait until it's watered and properly seated, then run a couple of chopsticks into the soil alongside the cutting, so as to help keep it vertical. Mainly keep the pot out of the way of traffic so it doesn't get bumped.

As for timing & exposure, this is what I do (and what has worked for E. trigona here). Cut carefully and do not get the sap on your hands, and especially not on your face, when you do this. Allow the sap to ooze out onto a paper towel and after a couple of hours you can handle the cutting without too much concern. The cold water trick speeds up this process. Leave the cutting in bright shade (lots of reflected light but no direct sun) for a week or so. Ideally use an area with good ventilation. I like a spot right outside our front door which is under an overhang but directly in the path of the prevailing winds.

Then set the cutting up for rooting mostly on top of soil in a smallish (not deep) container and water regularly (waiting for the soil to dry out each time). During the rooting process give the cutting bright light but little direct sun. Indoors ideally provide hours of daily sun during this period and beyond (indoor sun is not direct because a lot of the UV is filtered out by window glass).

These plants tend to have a seasonal growth pattern here and you may see the cutting sit there apparently doing nothing for months or maybe a year. Do not despair. And do not overwater. They tend to root first and grow later, so once you see new growth on top you have a pretty good indication the cutting is rooted and ready for a step up in pot size. From there on out try to provide strong light so the new growth is compact. These two plants are a few years old and they get about half a day of sun.

herrwood said:Plenty of good advice I think I am about ready to operate.
As I do not know a lot about gardening in general I do whatever seems to make sense
which usually works ok for me. This plant is one I do not want to screw up, its my wife's so When the top is removed can I just put it in the new soil. That is what i do with my outside Opuntia ( I am only now learning these names) and they just keep on growing.
I have been reading here about letting a plant dry and root before cutting which does have me confused as what to do.
Ed

Not to worry, Euphorbias are easy to start. I have had a 95% success rate. Unlike cactus, you do not need to stand the cutting on top of the 'dirt'. It is easier to make them stand up buy burying the cut end. For a 12 inch tall cutting I use a 3 inch x 3 inch deep pot of well drained mix. Wet the mix first, make a wide enough hole almost to the bottom of the pot and pack the dirt around the cutting.
The roots will grow out of the bottom cut in a month or two and the top will put on new growth to let you know it is happening. Water it when the dirt gets dry, but don't let the dirt stay dry for too long or the new, tender roots will die. I would re-pot it next spring when the root ball is full. Some species like E. grandialata take 6 or more months to root. Most are quick and easy.

You do need to let the cutting dry or "harden". This takes overnight or a couple days at most. This is true of all succulents except for cactus. Cactus need to form a callus, which can take months.

I always start cactus cuttings on the top of the soil and start 'tree type' Euphorbias buried in the soil mix.

I once buried the bottom of a Euphorbia ingens cutting 3 feet into the soil, and the tree grew like gangbusters. But that would be an extreme exception.

The reason why I recommend not burying the plant in question is that its ID is not settled in my mind. E. trigona is ridiculously easy to start from a cutting, some of the other similar Euphorbias much less so. Rather than test the limits of each plant, I prefer to give them the benefit of the doubt. Bad things will happen when you bury too much stem of a Euphorbia cutting, as I have discovered several times.

On the question of callus, the distinction in my mind is not between cactus and Euphorbia, but based entirely on exposed surface area. Some cuttings you can make with a tiny nub of a cut stem, because of the shape of the plant, and those you can pretty much stick right into the soil. As the cross sectional area increases you have to provide more and more time. With a wide stem (like on a wide columnar cactus or Euphorbia) it can go up to a couple of weeks. You can rush the process by powdering the exposed stem but the easiest thing is to just park the cutting somewhere until it's ready. The alternative is wait overnight and plant the cutting in soil, but be sure not to water for the rest of the required time it takes to heal.

It will be a week or so before I get to work on this but since it was pointed out I can cut a few feet off the top I should be able to start 2 or 3 so will have a chance to experiment a little with the above suggestions.

Baja_Costero said:I once buried the bottom of a Euphorbia ingens cutting 3 feet into the soil, and the tree grew like gangbusters. But that would be an extreme exception.

The reason why I recommend not burying the plant in question is that its ID is not settled in my mind. E. trigona is ridiculously easy to start from a cutting, some of the other similar Euphorbias much less so. Rather than test the limits of each plant, I prefer to give them the benefit of the doubt. Bad things will happen when you bury too much stem of a Euphorbia cutting, as I have discovered several times.

On the question of callus, the distinction in my mind is not between cactus and Euphorbia, but based entirely on exposed surface area. Some cuttings you can make with a tiny nub of a cut stem, because of the shape of the plant, and those you can pretty much stick right into the soil. As the cross sectional area increases you have to provide more and more time. With a wide stem (like on a wide columnar cactus or Euphorbia) it can go up to a couple of weeks. You can rush the process by powdering the exposed stem but the easiest thing is to just park the cutting somewhere until it's ready. The alternative is wait overnight and plant the cutting in soil, but be sure not to water for the rest of the required time it takes to heal.

Very good advice Baja. The 'exposed surface area' is a great way to put it.
Most Euphorbias are simple as pie, but a few have been temperamental.
Any ideas why my E. grandialata takes so much longer to root?
The plant is very similar in size (cross section) to a E. trigone and the buried base does not rot.
But the forming of roots requires 6 or more months, even with rooting powder.
As always I am your student.

And likewise.

It is a mystery to me why some Euphorbias are so reluctant to root, and others take off. It seems to depend on the plant and sometimes on the season. Presumably individual Euphorbias are different that way. Usually I try to forget about cuttings for a while but when it starts taking more than a year then I start to doubt if it's ever going to happen. No doubt there are tricks and tweaks that I haven't tried.

Even the easiest Euphorbia to start from cuttings here (E. ingens.... stick a cutting in the ground and you cannot fail) tends to skip a growing season while it sorts out the situation below ground.

E. tirucalli & tithymaloides take off well, but are different style/structure types of plants. I stick cuttings 2-4" deep, until they're deep enough to stand up straight.

tithymaloides stem put in ground around 6 weeks ago:



I stuck these pieces of tirucalli in this pot with all of these other cuttings last weekend, pic from today:


These cuttings were put here about 3 months ago. The ones to the left and at the bottom are making new, bright green stems from below the ground.


Those are the 2 kinds of purposeful Euphorbia that I have. (Tons of E. maculata & nutans sprouting out there right now.)

I also grow some Euphorbias, and what I learned with them, to root a cutting, I make sure cutting is callused then stick it not too deep in gritty soil and in part shade area. It will then acclimate to set-up and wait till temps are warm enough. So the timing you do the rooting is important. Warm will be when daytime temps have reached 70 to 85F and overnights are above 50F.

When temps go extremely high, like 95F and higher, as with most cuttings, it waits. But once it is rooted, it loves watering here, since our area is just so dry, and can take our full sun by then.

I only have them in small containers, since I have to move them indoors during our wet winters. During winter, I bring them indoors by our south facing window and kept dry.