Can you show pictures?

ditto... there are several plants known as pencil cacti and some are not in the cactus family at all.. most common one in cultivation is a Euphorbia called Euphorbia tirucali. It is only extremely remotely related to a cactus. If this is the plant you are referring to, 5' would hardly be considered huge, as most cuttings start out at about that size. These quickly grow into trees over 25' tall and 30' wide. Famous for having even more irritating sap than most Euphorbias, do.

but either way, for most succulents and cacti, taking them out of their pots and examining their roots is not stressful and most tolerate that easily... can save their lives, too, as it allows you to identify rot, or root mealles, and cut the rot away or hose off the mealy bugs. And change your soil, too.

5' is large for a lot of NYers. We are not all living in Succulent heaven. I remember seeing my first 30 ft pencil cactus next to a 20' Euphorbia ingens in Hawaii. No one had prepared me for the reality of their true natures. It did not compute. I felt like Alice in Wonderland after she had eaten the "little" pill.

Thanks for the info guys. As you can see the stem was rotting and was not doing that well and needed to do something. I examined the soil and roots, and did seem like root rot. For some reason the pot wasn't draining well, and the soil was still wet despite the fact that I hadn't watered in quite a while and had a hole on the bottom. I ended up cutting up the whole plant (the healthy looking parts) in hopes that the cutting will at least survive. Any ideas on how best to plant the cutting of this plant that was suffering from root rot? I've tried planting cutting of this before but they never took. But doesn't seem to be an easy one to propogate. Thanks again for your help!

Judging from the pencil cactus form, it need much more light to be happy. The segments are spindly from all the shade. Can you describe the soil? It needs to be a fast draining mix. Lots of perlite, or grit. It loo;s really black, rich and bad for a Euphorbia.

Once you decide on a soil, one cuts off the rotted roots and let the cutting callus or get hard on the end. a week is a good time. then you stick it in the soil, and mist it. Do not water it. Mist it. At this time of year, your plant is probably going into dormance and it will not root till spring. One can pile some rocks around it to hold it up, but , with that height and thinness of the stem, one miight have to devise a means of propping. I have never rooted anything in the cold north so maybe one should wait to see if others from north of the sunbelt/Mason Dixie line has some pointers. I am still in the 90's and we are headed into a growth cycle. I imagine that rot is harder to avoid in your situation. I would make the soil very gritty. Pine bark, perlite, cjicken grit or Cactus soil and at least equal parts chunky perlite. Not the fine dusty stuff the big box stores sell.

agree... this is probably the easiest of all the succulents to root in my experience. Never had one not root. But you certainly need full sun, outdoor living (for now) and the right soil (even 100% pumice will be good for now). I just use Home Depot cactus soil and, if humid or rainy, add 50% pumice or perlite to it. If indoors, maybe 80% perlite or pumice (you want the soil to drain so fast that it feels dry hours even after you water it thoroughly). Growing one of these indoors is a challenge, I have to admit. They hate growing out of full sun and in any low light situation. Good luck!

What terrific advice! I was just admiring one last night in my neighbor's front yard. He says he brought it here as a 2' cutting about 5-6 years ago and the thing is probably 20' tall now. I'll try to get a shot of it later.

I had a cutting from a friend down the street in Hawaii. It grew quickly to 8 ' when I sent a cutting to my mother in Houston after she lusted over it during a visit. I then moved to Austin and three months later she moved to Hawaii and she gave me the plant. I then sent her a cutting from my new to me plant since she was too shy to walk down the street to my friend the original source and get a cutting off the 20' monster, so The last I saw it , it was also approaching 20 '. I killed mine in a freeze so I grabbed another cutting off of hers on a christmas visit.