Salvaging a Gymnocalycium mihanovichii using hydroponics

[The_Nikon_Guy]

So, the story goes like this... I had this beautiful Gymno growing in a terracotta pot for about 3 years when, after a particularly dry spell and heat stroke, it decided to just kinda give up on life. No amount of encouragement resulted in any benefit and it just sat there in a variety of soils/artificial climatic conditions etc shrivelling until I was convinced it was a hopeless situation.
It wasn't until I remembered reading an article wherein the grower manages to salvage a few of her cacti using hydroponics, that I thought to give it a try.
I dug out the gymno ever so gently from its soon-to-be grave and mixed up a 0.5 gm/litre concentration of a 20-20-20 (NPK) with micro-nutrients solution and after a bit of root cleaning to remove the excess soil, proceeded to place it in the solution. So here we are about 2 weeks into the experiment and lo and behold - its begins to sprout masses of white roots with super-fine root hairs - good on ya girl I thought.
My wife and I were so excited that we thought it a good time to share this news with those of you who might be considering this method in order to save a precious cactus of yours.

IMG_20201211_155327.jpg (83.98 KiB) Viewed 1858 times

IMG_20201211_155402.jpg (113.09 KiB) Viewed 1858 times

Once the gymno reaches peak health and is nice and plumped up, I intend to migrate it back into soil. Once again, we'll keep you guys posted on that score.

[558cbs1012]

Nice job! I have an obesa i need to try this method with

[dinfelu]

very good news, I had not thought about it, I will save your story in case it happens to me

greeting

[Mrs.Green]

Interesting. I have been thinking along these lines too as a last try for rescuing . A couple of points of ‘concern’ though.. The possibility of rotting of the base if the base comes in contact with standing water ( as in the pics?) and as I have understood, the roots developing in water and substrate, isn’t the same. Would be interesting to know if any of the really experienced cactigrowers have any insight on this subject?

[Steve-0]

https://www.google.com/search?q=hydopon ... e&ie=UTF-8

Have a look.....not my cuppa...but it appears to have some traction.

[The_Nikon_Guy]

Interesting. I have been thinking along these lines too as a last try for rescuing . A couple of points of ‘concern’ though.. The possibility of rotting of the base if the base comes in contact with standing water ( as in the pics?) and as I have understood, the roots developing in water and substrate, isn’t the same. Would be interesting to know if any of the really experienced cactigrowers have any insight on this subject?

Your'e concerns are both valid.
For the base rotting - I guess I'll just have to check it every day or so. I'm under the distinct impression though that rotting usually occurs when there is an open wound? I might be wrong.
Yes, the water based roots are different to soil based roots for a variety of reasons - this article explains this quite nicely I think. I intend to follow this article's instructions quite closely.
I'm also going to try and increase the chances of success by making sure the Gymno is nice and plump before performing the transplant - basically gives it more time to adjust.

[The_Nikon_Guy]

Nice job! I have an obesa i need to try this method with

sure thing, we'll keep you updated on our progress.

[The_Nikon_Guy]

The gymno inflated to a large size and became very turgid - I guess all those roots sucking in those nutrients worked a treat
I transferred the hydroponics container outdoors for a week to get the gymno acclimatised to our hot Perth summers and then two days ago, potted it into a coarse potting mix containing 50% grit/sharp sand/rock particles ~2-3mm + 50% professional cacti potting mix with the super fines sifted out.
I then drenched the pot in a hydroponics nutrient solution and let it drain out - suffice to say, the soil was thoroughly moist - but not soaking wet.
We have been checking the turgidity of the cactus over the past couple of days - mind you, the temperatures have been 42-43 Deg C over the past two days - and it is doing absolutely fine - fingers crossed. The photo below gives you a better idea:

2020-12-24 Gymnocalycium mihanovichii repotted.jpg (90.43 KiB) Viewed 1700 times

[7george]

These like warmth and heat. That soaking performed during North hemisphere winter would have different outcome...