Persistently unhappy Micropuntia

[CactusFanDan]

So I bought this Micropuntia some time last year (I think, might've been the year before) from the Cactus-art nursery and it's pretty much just sulked since then, despite every other plant in my collection doing fine in the same soil mix. Anywho, I got a bit bored with trying to coddle it along in it's current state and I figured something was up with the roots so I unrooted it and stripped the root system down as much as I could. There was quite a lot of dead root tissue, which could explain why it wasn't really doing anything. So I removed everything back to the taproot, so it should be able to grow roots more easily now. Any tips on how deep I should plant this? I find that long neck bizarre. Would the plant benefit from having the long, slender neck underground?

I do hope this plant picks up at long last.

The end result

DSCF4095.JPG (55.57 KiB) Viewed 1565 times

[Steve Johnson]

I'm not familiar with the genus, so what kind of root structure do they have?

[Saxicola]

Are you sure the root is still alive? Also, make certain the main stem is alive too. I found one of my young caudiciform plants (a Bursera). I had healthy roots and healthy upper stem but the stem at the base (i.e. inbetween the two parts) had died. I cut out that part and now I'm trying to root the top and I'm hoping the base will send up a new stem.

Assuming the whole plant is alive, try putting it in pumice. I've had many cacti languish in more standard "soil" mixes really thrive in a pure inorganic media like pumice.

[sabotenmen]

Are you sure the root is still alive? Also, make certain the main stem is alive too. I found one of my young caudiciform plants (a Bursera). I had healthy roots and healthy upper stem but the stem at the base (i.e. inbetween the two parts) had died. I cut out that part and now I'm trying to root the top and I'm hoping the base will send up a new stem.

Assuming the whole plant is alive, try putting it in pumice. I've had many cacti languish in more standard "soil" mixes really thrive in a pure inorganic media like pumice.

If I’m not mistaken, pumice is not easily available in the UK, Saxicola..At least not at a reasonable price. But mineral is definitely the way to go here.

[DaveW]

Micropuntia's are tuberous rooted. As you know Dan I believe that all plants should be planted to their original sol level. The problem is deciding what that was if somebody has tried to turn them into a pseudo-caudiciform in the past by planting much of the underground stem or root unnaturally above ground.

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[CactusFanDan]

Are you sure the root is still alive? Also, make certain the main stem is alive too. I found one of my young caudiciform plants (a Bursera). I had healthy roots and healthy upper stem but the stem at the base (i.e. inbetween the two parts) had died. I cut out that part and now I'm trying to root the top and I'm hoping the base will send up a new stem.

Assuming the whole plant is alive, try putting it in pumice. I've had many cacti languish in more standard "soil" mixes really thrive in a pure inorganic media like pumice.

The root system's alive, since I scratched part of if down to some nice looking live tissue. I'm not sure all the tissue in the long neck like bit is still alive, but I feel like cutting it all off might be the final death sentence for this plant. The cladodes at the top are all alive and quite firmly attached, and they're even a little green in the points between cladodes. I'm fairly sure they'd all be dead if they weren't being sustained by the storage root.

I'm not entirely convinced the soil mix is the problem, since this is the only cactus which has languished in my mix. I'll try it again now that I've reduced it to a state which should allow it's roots to grow a bit more easily. However if that still doesn't work, I'll try a mineral mix.

[Steve Johnson]

I'm not entirely convinced the soil mix is the problem, since this is the only cactus which has languished in my mix. I'll try it again now that I've reduced it to a state which should allow it's roots to grow a bit more easily. However if that still doesn't work, I'll try a mineral mix.

Actually, I think your mix could be more of a problem for the Micropuntia than you realize. Before I say anything further, please let me know what the ingredients are and the approximate percentage of each.

[sabotenmen]

I'm not entirely convinced the soil mix is the problem, since this is the only cactus which has languished in my mix.

Ok, but what you need now is roots, and fast, and plants root much faster in a mineral mix.

[Steve Johnson]

Ok, but what you need now is roots, and fast, and plants root much faster in a mineral mix.

I tend to blather on with TMI, so sabotenmen cut to the chase rather nicely. I'll expand further, but hopefully not TMI this time...

Dan, I think what happened is that your Micropuntia's feeder roots (if that's the correct term) got suffocated in the amount of soil you have in your mix, so they weren't able to regenerate and grow out properly. If you lean out the mix and use less soil, my educated guess is that a higher mineral-to-soil ratio more in favor of the mineral will aerate the taproot sufficiently to let the feeder roots come back. Going totally soil-less is a good concept in theory, although you won't be able to do it purely with clay-fired cat litter or grit since both have zero CEC. Pumice doesn't have that problem, although its low CEC is the reason why I have to fertilize every time I water my cacti. Unfortunately academic from your perspective since you can't find it in the UK. It's possible that other minerals such as scoria may have CEC properties similar to pumice, but it's something I haven't investigated since I have no need for anything beyond the pumice and DG I use for my soil-less cacti.

I had difficulties when my Tephros languished and did nothing for 2 years. Then when I discovered what was wrong down below, I finally hit upon the proper solution a year ago. While the details aren't important, I can tell you this -- one of my paper-spines pushed out new stems 3 months after I changed the mix. A stem I re-rooted took its time to establish and grow in during the course of the growing season. Now that paper-spine is pushing out a new stem of its own. My pine cone Tephro hasn't done much yet, although it did plump up after I watered it a few weeks ago. When the weather gets consistently warmer later this spring, I'll have to look out for the appearance of new stems in May or June. If my story heartens you at all, then my gut intuition is that if you adjust your mix to suit the Micropuntia along the lines of what we're discussing, you may see it from sulking to growing before the summer is done. And you have plenty of growing season left for it. If you decide to go for it, I'd be keenly interested in following your progress -- please keep us posted whichever way you go!

[CactusFanDan]

Roughly: 20% topsoil, 30% sharp grit and 50% cat litter (expanded moler clay pellets, similar properties to pumice). Plus some other minor ingredients. I'm not convinced it's the problem owing to what else I've got thriving in this mix including lots of other tap-rooted Opuntiads: Tephrocactus, Cumulopuntia, Cylindropuntia, Grusonia (which are basically the same as Micropuntia!), Maihueniopsis etc. Also there are plenty of other tap-rooted plants with fine feeder roots growing in my mix: Ariocarpus, Strombocactus, Lophophora, Sulcorebutia, Copiapoa, Lithops and others. Not to mention all my Eriosyce, which love it. I do have a few plants in a totally 'mineral' mix and they all look a bit sulky and the pots tend to get a bad salt-build up in them.

[Steve Johnson]

Roughly: 20% topsoil, 30% sharp grit and 50% cat litter (expanded moler clay pellets, similar properties to pumice)...I do have a few plants in a totally 'mineral' mix and they all look a bit sulky and the pots tend to get a bad salt-build up in them.

Okay, then the mix seems fine. Wish I could help you more, but I have no idea why the Micropuntia doesn't want to perk up yet. If you're trying to grow cacti in nothing but your cat litter, the bad salt buidlup you're describing would be consistent with the fact that it doesn't have any cation exchange capacity. Without CEC, fert gets deposited on the clay pellets instead of being taken up through the roots when watering. Maybe similar to pumice in some respects, but not in the one that really counts here. Wish I knew the chemistry behind it, though.

[DaveW]

Some cacti when they loose their roots can be pigs to re-root again even if potted in a suitable compost and will just lie around for months or even a year or so before re-rooting. Plants go at their pace not ours!

[CactusFanDan]

If you're trying to grow cacti in nothing but your cat litter, the bad salt buidlup you're describing would be consistent with the fact that it doesn't have any cation exchange capacity. Without CEC, fert gets deposited on the clay pellets instead of being taken up through the roots when watering. Maybe similar to pumice in some respects, but not in the one that really counts here. Wish I knew the chemistry behind it, though.

Aye, I don't think a mineral mix is necessary or beneficial for the plants which are in it anyway. I'll repot them soon enough.

Ah well, I guess I'll just try all the tricks in the book to try and get it going again. I'll report back if I'm successful.