Sick cactus - what to do?

[altcorn]

Hello cactus lovers,

I have a beautiful tall cactus in my living room who has been droooping a bit and showing more and more dark spots (see pictures)
What do I do? does it lack nutrients? It's been indoors in a big pot for a long time, just 1 gallon of water a month.

Worried sick cactus dad

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[Steve Johnson]

First of all, see this:

viewtopic.php?t=43819

For good or ill, everything starts out in the roots, and I'm willing to bet that you've been growing your cactus in potting soil. If that's the case, you'll need to lean it out with mineral gravel for better drainage and aeration of the roots. Pumice is great, although if you can't get it, other options are perlite and calcined clay granules. The mix itself is pretty straightforward -- 50% soil mixed in with 50% mineral ( you might go a little leaner with 60% mineral and 40% soil). Unpot the plant, clean out the soil, and take a good look at the roots so you know what you're dealing with. Photos of what they look like would be helpful.

[altcorn]

Thank you Steve, I will try and report back with pictures.
It's going to be tough since the cactus is roughly 8 feet high. Shall I use a blanket to maintain it while unpotted?

[Steve Johnson]

It's going to be tough since the cactus is roughly 8 feet high. Shall I use a blanket to maintain it while unpotted?

Not a bad idea, and at least it'll keep your floor clean.

[altcorn]

Hello,

Hello,
I unpotted the cactus just enough to take a good look at the roots.
The roots were flexible and felt just a bit humid. they looked healthy to me (flexibility, humidity, color, no smell .

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the picture on the floor is a small piece of root I cut inadverteltly with the tool while digging out.
There were some pebbles mixed with the soil. I put the soil back afterwards.

Please let me know our thoughts

[Steve Johnson]

The roots should be a lot more extensive. All you can do is take your cactus (I think it's a Trichocereus, by the way) completely out of the pot, clean off the soil, and repot in the 50% mineral/50% soil mix I recommended. Unpotting and repotting an 8-foot tall cactus is quite a challenge, so best if you have someone who can help you do the repotting. Don't even think about watering until the plant starts growing a new root system next spring.

[altcorn]

Thank you! should I do anything about the spots?

[altcorn]

Other question: to take it out, can I lay it on the ground sideways?

[Steve Johnson]

Thank you! should I do anything about the spots?

Unfortunately, there's nothing you can do -- extensive damage on the stems is due to the absence of a healthy root system. If your cactus can grow a new root system, it'll undo at least some of the damage from the inside out. This is a very long process, and more I think about it, the more I'm of the opinion that you shouldn't water at all in the spring, and do some occasional light watering in the summer -- just enough to moisten the mix without drenching it. This will "tease" new roots into growing as they seek out water while the mix is dry.

Other question: to take it out, can I lay it on the ground sideways?

Absolutely! In fact, that would be a good opportunity to check each stem and see if any of them are healthy enough to take as cuttings so you can root them. Post photos of each stem in the sideways position, and I'll point out the ones you can cut, then give you instructions on what to do. Even if the entire plant is beyond hope, cuttings will give you the ability to save what's left. After you unpot it, don't do anything until I can see the photos.

[altcorn]

Thank you so much! I lke having a plan forward, I feel better already

[altcorn]

Hello,
I rooted the cactus 2 months ago and am waiting for the spring. I see, however, that the limp and grey-ish branches seem to be expanding. Should I cut these limbs?

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[Steve Johnson]

These are the instructions I gave you on November 12:

Other question: to take it out, can I lay it on the ground sideways?

Absolutely! In fact, that would be a good opportunity to check each stem and see if any of them are healthy enough to take as cuttings so you can root them. Post photos of each stem in the sideways position, and I'll point out the ones you can cut, then give you instructions on what to do. Even if the entire plant is beyond hope, cuttings will give you the ability to save what's left. After you unpot it, don't do anything until I can see the photos.

Unfortunately you didn't follow them. The cactus may be too far gone with extensive fungal disease at this point. And my apologies for being blunt about it, but 8-foot tall columnar cacti aren't suitable as houseplants -- they really need to be outdoors where they get plenty of sunlight and good ventilation.

[altcorn]

Hello, I should have posted the pictures to each stem individually. I still would like to try to save what I can of the cactus.
I understand if you dont want to post any guidance anymore but I would welcome any input. Thank you!

[7george]

And my apologies for being blunt about it, but 8-foot tall columnar cacti aren't suitable as houseplants -- they really need to be outdoors where they get plenty of sunlight and good ventilation.

That was my first thought when I saw pictures. Even in a greenhouse these cause lot of problems for growers: need for trimming and difficulties with re-potting because of massive root system. Keeping them in the same pot and soil in shady spot for 10 - 20 years makes them weak and easy to get sick. So better do not stick to first plants gotten as a gift or heritage but think what would be growing well in your conditions.