Plumping up Opuntia paddles

[Shane]

I rooted some to use as graft stocks, but they've never really gotten very full. I'm looking for suggestions of how to get them a little fatter. My experience in general with opuntia cladodes is they root well then are very stubborn when it comes to doing anything else

[Carbo]

It's easy, after you root a cladode cut off any offsets as soon as they appear, the sooner the better. The cladode will have no growth points on it and will divert all energy into secondary growth. Water and fertilizer helps too, as does over-potting it a bit. You can do this with any cacti, just remove as much new growth as possible and the cactus will fatten up real good. With hylocereus for example, it's fairly easy to remove all areoles and stems can get nice and thick this way which also leads to explosive growth once you graft something on it. It's harder with species which branch excessively like mammilaria prolifera but i've removed pups on a regular basis from said plant and the "main" plant got huge in comparison with untouched individuals.

Edit: I've just realized that you might be talking about pads not wanting to fully hydrate, if so than my answer is useless

[Shane]

Edit: I've just realized that you might be talking about pads not wanting to fully hydrate, if so than my answer is useless

That was what I meant. Cladodes will root then just do nothing for me, not even fully hydrate (this seems to be a problem more for larger paddles for whatever reason). I'm thinking possibly water is the issue. I used loose, well draining soil to help them root, and maybe they haven't gotten enough water

[mikethecactusguy]

Hey Shane.
I have about a dozen individual pads that have fully rooted but have been inactive for over a year now. Last month 2 suddenly sprouted new pads.
We can not force mother nature sometimes.

[Carbo]

That was what I meant. Cladodes will root then just do nothing for me, not even fully hydrate (this seems to be a problem more for larger paddles for whatever reason). I'm thinking possibly water is the issue. I used loose, well draining soil to help them root, and maybe they haven't gotten enough water

I can think of 2 things that might be the problem, the 1st as you said- the substrate might not retain water for long enough for the plant to absorb it. 2nd thing, the soil might have too much soluble salts in it or the PH might be too high/low. In any case I've had great success hydrating cacti by using rainwater or distilled water, distilled water has very little or no solubles in it at all, allowing the cactus to soak it right up like a sponge. Be careful though as I had some literary crack from absorbing too much water.

[Shane]

Thanks for the tip. As luck would have it, rainwater is abundant here right now as it's the wet season for us

I'm curious if you happen to know the physiological reason minerals inhibit absorption into the plant

[Carbo]

Thanks for the tip. As luck would have it, rainwater is abundant here right now as it's the wet season for us

I'm curious if you happen to know the physiological reason minerals inhibit absorption into the plant

I do, it's because of osmosis. Water always moves towards higher solute concentrations. As for further explanation, I've no idea why but if you expose any salt to open air it will absorb moisture from it, soluble stuff seems to have affinity to water.
So when you water plants with (near)pure water, the water rushes into the plant because liquids inside plants have higher solute concentrations. This even works if we as humans drink distilled water, your lips will swell as well as your tongue and throat as water rushes into the tissues ( so don't try this at home-or anywhere really).

Edit: when concentration of soluble salts is high in the substrate it inhibits absorption because of reasons mentioned above, if concentration of solutes reaches higher levels than in the plant, water actually starts flowing out of the plants and into the soil, dehydrating it among other things.

[teo]

This even works if we as humans drink distilled water, your lips will swell as well as your tongue and throat as water rushes into the tissues ( so don't try this at home-or anywhere really).

But rainwater is (regarding salts at least) distilled water. That would mean you ca't drink rainwater???

[Shane]

I do, it's because of osmosis. Water always moves towards higher solute concentrations. As for further explanation, I've no idea why but if you expose any salt to open air it will absorb moisture from it, soluble stuff seems to have affinity to water

Ah! Osomsis! That makes sense. As for how it works at chemical level, I actually know that. Water can diffuse through the plant's tissue but salts can't (or can't nearly as easily). Were this barrier not there, the amount of liquid and salt concentration would equalize, but since the salts can't move through the plant tissue only the concentration equalizes. Which means more H20 where there are lots of salts and less where there are fewer

Thanks again for the tip!

[esp_imaging]

if we as humans drink distilled water, your lips will swell as well as your tongue and throat as water rushes into the tissues ( so don't try this at home-or anywhere really).

Not true. Drinking water in general has vastly less dissolved matter than (for example) blood plasma. Compared to many human (or plant) fluids, distilled water and rainwater are both largely pure water, excluding dissolved gases.
Biological systems have various mechanisms for managing solute concentrations in fluids, including various "pumps" capable of operating against osmotic pressure. An example of this is urine production - if a person has not drunk much water, their urine can have much higher concentration of salts than the blood plasma passing through the kidneys.

[Carbo]

Not true. Drinking water in general has vastly less dissolved matter than (for example) blood plasma. Compared to many human (or plant) fluids, distilled water and rainwater are both largely pure water, excluding dissolved gases.
Biological systems have various mechanisms for managing solute concentrations in fluids, including various "pumps" capable of operating against osmotic pressure. An example of this is urine production - if a person has not drunk much water, their urine can have much higher concentration of salts than the blood plasma passing through the kidneys.

A guy on youtube actually drank very pure water (but it was deionized one, not distilled...idk what's the difference), and I seemed to remember the video wrong, he didn't experience swelling but he did have burning sensations from cells directly in contact with the pure water most likely bursting from taking up too much water as he described it: https://www.youtube.com/watch?v=FElDa62zwwE (skip to 5:45 to when he describes aftermath).

Rainwater has less solutes in it than your average tap but still enough to not cause any such effects.

[esp_imaging]

Not true. Drinking water in general has vastly less dissolved matter than (for example) blood plasma. Compared to many human (or plant) fluids, distilled water and rainwater are both largely pure water, excluding dissolved gases.
Biological systems have various mechanisms for managing solute concentrations in fluids, including various "pumps" capable of operating against osmotic pressure. An example of this is urine production - if a person has not drunk much water, their urine can have much higher concentration of salts than the blood plasma passing through the kidneys.

A guy on youtube actually drank very pure water (but it was deionized one, not distilled...idk what's the difference), and I seemed to remember the video wrong, he didn't experience swelling but he did have burning sensations from cells directly in contact with the pure water most likely bursting from taking up too much water as he described it: https://www.youtube.com/watch?v=FElDa62zwwE (skip to 5:45 to when he describes aftermath).

One person's you tube video hardly constitutes great science, does it? At the time he reported no effects, the next day he reported a burning sensation. Maybe he ate chilli? Maybe it was in his head? Where was the control group?

Rainwater has. . ..still enough to not cause any such effects.

I assume this is pure speculation?
Rainwater could be extremely pure, depending upon source and how it is collected.

[Carbo]

One person's you tube video hardly constitutes great science, does it? At the time he reported no effects, the next day he reported a burning sensation. Maybe he ate chilli? Maybe it was in his head? Where was the control group?

Rainwater has. . ..still enough to not cause any such effects.

I assume this is pure speculation?
Rainwater could be extremely pure, depending upon source and how it is collected.

Maybe you're right but you can easily get deionized water and try it, I would bet that you'd experience burning effects, it just makes sense that water would be able to overcome cell's natural ability to fight osmosis because it's so pure. I'll get some and try it myself.

As for rainwater, when water condenses high in the atmosphere it needs a particle to condense onto, so at the very least it will have that particle inside it, which may be a compound that's soluble. As water droplets fall through the air, it's very likely they'll pick up more soluble compounds as they fall.

In any case, both do wonders with hydrating any plant, as I've said I had specimens burst open when using rainwater.

[Shane]

I assumed rainwater was pretty much pure but never really thought about it. Guess it depends on what your definition of "pretty much pure" is though. It's hard to find figures for total dissolved solids in rainwater or di water, but rainwater is single digit ppm and di water is single digit ppb. So for most purposes rainwater is pretty much pure, but compared to di water is pretty dirty

Where do dissolved solids come from in rainwater? Dust. Sure there isn't that much dust in the atmosphere (usually), but 7 ppm isn't much either

Now I'm questioning how pure my rainwater is now. It came off a roof which is basically a giant dust trap. Next time it rains, I'm going to collect water mid storm so I hopefully get less contamination

[esp_imaging]

De-ionized water may be less pure than distilled water as non-ionic (e.g. organic) components won't be removed by the de-ionization process, that's down to filtration or any other additional purification .

Do a google search whether is it safe to drink distilled / de-ionized water. It is, just like the rainwater which it so closely resembles.