This is a cactus I bought from Lowes many years ago. It is 7 feet tall. Can anyone give me an id on this? I used to be able to bring it in when temps were below freezing but now I have to cover it. Any other info on it will be appreciated, it has never bloomed.

thanks

Anole

I am no help with an ID, but just curious, how big was it when you got it?

Pachycereus marginatus?

Mexican Fencepost Cactus (Marginatocereus marginatus)

When I bought this at Lowes years ago, it must have been 4-5 inches tall.

Thanks Baja for the id.

Anole

I second Baja! P. marginatus for sure.
Here is one of mine:

When they have a good source of water and well draining soil these things can get gigantic.
Unfortunately I do not have a good picture, but the tallest stem that you can see in the picture doubles in thickness about halfway down - that was its growth habit when I got it. A friend had grown that next to a patch of roses that got very regular irrigation. The thing was easily two and half stories tall and that is what did it in: a big monsoon storm and it came crashing almost took out his car. I got the top 3 or so feet of it. It gets a lot less water from me so it is not continuing its thick/quick growth, but doing quite well nonetheless. They do get tippy when tall.
These should be able to take 9a I think, they take 9b without a problem for sure... My photos are not organized enough to post a pic of its flowers, mine have never flowered, but I have seem them in flower in the Desert Botanical Garden in Phoenix.

The cactus on the right is one of its cousins: Pachycereus pringlei, those are more frost tender than P. marginatus.

Mcvansoest, thanks for the post, mine is getting tippy as it is in a pot. I am thinking I should put this guy in the ground. South Louisiana ground tends to be wet a lot. If it were to fall, are you saying that I can grow a new plant by cutting off the top?

Anole

Hi Anole,

Yes! you can grow these cacti really well from cuttings/offsets. If a limb was to fall/break off - leave it sitting around in a dry place for a few days to let the cut/break dry out and callous over. Then stick it in a pot with well draining soil and leave it be. Initially you want to really minimize/avoid watering the plant as it has no roots, once a few roots are established (you know either by seeing new growth or feeling that the cactus is more solidly stuck in the soil) you can start providing some water (or letting it catch some rain).

If you decide to put your big plant in the ground, amend the soil immediately around the plant in such a way that it drains/dries out pretty fast because long term wet feet is what will kill the plant for sure. It can definitely take lots of water, but enjoys dry feet. If you can get your hands on some pumice, you can mix that in with a part local soil, and a part well draining cactus soil and back fill whatever hole you dig for the cactus with that - you probably also will want to use some of that mixture below the cactus.