Help please! cactus not well

[yma]

I've had a rat's tail cactus (Cleistocactus winteri?) for about 3 years now. Over the last few months part of it has been turning brown (base and stems on one side). I'm not sure what's wrong with it - I haven't changed anything I'm doing and have been following the care instructions originally provided. I'm not very experienced with cacti and would really love to save it (it was a gift from a dear friend). Any help would be appreciated!! Thanks.

brown and short on one side - mostly green and happy looking on other

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problem area

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[Steve Johnson]

Really difficult to do a "remote diagnosis" from your photos. (Probably correct on your ID -- I believe C. winteri is the most common of the genus.) If your cactus has been under the same growing conditions for 3 years, perhaps it has been attacked by something. Could be spider mites. If that's the case, your first clue will be extensive webbing all over the stems. Spider mites are pretty much impossible to spot with the unaided eye, and by the time you see their nasty webs all over the place, you'll have a full-blown infestation on your hands. Let me know if this seems to fit the description. If it doesn't, I'm really not sure what could be happening. Maybe we can come up with some other ideas.

[Peterthecactusguy]

looks like it is dying and it looks like some of the stems might be etiolated. I am not sure tho.

[yma]

I don't see any webs on the plant and the plant beside it seems fine.

Is it possible that this could happen from it outgrowing it's pot? It's never been repotted.

[Daniel]

Check the roots, they could be so tightly wound up in the pot that most of them are not getting enough water. or something could have caused them to rot away?

[Steve Johnson]

I don't see any webs on the plant and the plant beside it seems fine.

Is it possible that this could happen from it outgrowing it's pot? It's never been repotted.

Alright, so no spider mites -- that's good. If your rat's tail hasn't been repotted before, 2 things spring to mind. One is being root-bound. The other is the soil you have in the pot. Many cacti tend to be rather forgiving, although they can tolerate only so much before the wrong growing conditions become a real problem.

Daniel is correct, and the first thing you should do is unpot the plant and check the roots. If being root-bound is the only problem, you have 2 different options. One is to repot the plant into a bigger pot. The other is to prune the roots back enough so you can get some fresh soil into your existing pot. You should have a margin of about 1/2-3/4" between the root ball and the pot for the proper amount of soil to be in there. Much more than that and your plant will be over-potted, which means the roots won't absorb enough moisture to let the soil dry out as it should.

The soil itself can be trouble -- commercial "cactus & succulent" mixes are generally horrible, although that may be the only thing you have access to. If so, you'll want something you can add for better drainage in the mix. Pumice is absolutely the best if you can find it, although you may have to settle for something else. Avoid Perlite, since it floats away and it's a huge pain in the backside. Maybe Vermiculite would be okay. Sand is the worst possible idea since it does nothing for drainage. Anyway, the idea is to tilt your mix heavily in favor of drainage, at least a 50/50 mix of mineral product to soil.

Now, I don't think you're looking at root rot, otherwise you'd see the stems on your plant turning to mush. With that said, the brown stems are dried out and most probably dead, so there's nothing you can do beyond just removing them. When you repot the plant, you can concentrate on getting the growing stems healthy. (If you are having rot problems, let me know and we can discuss this further.) There are a couple of things to bear in mind here:

1. When cacti are repotted, they should be kept in dry potting mix for 1-2 weeks before first watering. After that, watering frequency depends on how long it take for the plant to re-establish and build new roots. In your case rat's tails are easy growers and watering every week or two should be fine.

2. Generally speaking, cacti (or at least desert cacti) go dormant in winter. At that time they aren't growing, and the roots won't take up moisture. I keep my cacti outside, so I'll give them very little (if any) water over the winter. If you keep yours inside, you may see signs of new growth here and there in winter, so some occasional light watering should be fine. But be very careful -- if you water your rat's tail in winter just like you would in spring and summer, the plant will be susceptible to rot.

There's one last item I should mention. And that is move your plant outdoors if you can. Indoor cacti won't do very well since they won't be getting the amount of light they need. When you see thin, leggy growth it's called etoliation, and not the healthiest thing for any cactus. I don't grow Cleistocactus, so I'm not sure how frost-hardy they are. Depending on how cold your winters get, it's something you should look into if you want to move your plant outside. If winter is a problem for you, at least you could move yours inside when the weather's too cold.

Let me know if you have any more questions, and I hope this helps!

[yma]

Thanks so much for the information! I really appreciate it.

[hoteidoc]

I've had a winterii for past 4 yrs. Basically offshoots from away-side, stop growing & go brown. I'm pretty convinced it's just lack of light, plant knows better & grows where sufficient light. Light-side branches are 5' +, have had multiple cuttings taken & keeps on truckin'