Ask a Question forum: Elephant ear leaves wilting

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Virginia (Zone 7a)
Rez
Nov 4, 2016 6:07 AM CST
I recently got this elephant ear and moved it to a large container about which I wrote here: The thread "Fillers for a big container" in Ask a Question forum

Now a few of its leaves have wilted. Three have hit the ground and one more is looking bad. I think it can be because of too much water. When I bought it it was over watered and there were water drops on the tips of the leaves.
One thing strange is that its soil in the new container doesn't get dry. I watered it a week ago and it is still as wet.
Name: Sue
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sooby
Nov 4, 2016 5:23 PM CST
The water drops on the tips of the leaves sound like guttation:

Guttation:
http://ipm.missouri.edu/MEG/20...

What may have happened to make the potting mix stay wet is that when you used the fillers at the bottom of the container it created what's known as a perched water table. If there is coarser material underneath finer potting mix, the potting mix won't drain until it is saturated. This the downside of using different textured material at the bottom of a pot, it causes the finer top layer to be wetter. If the humidity is high also then the plant won't use much of the water and nor will much evaporate from the mix.
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RickCorey
Nov 4, 2016 6:05 PM CST
If the problem is partly that the new soil is too fine, has few air gaps, and holds too much water, re-potting might be an option. Next time, add more grit, Perlite or screened bark chips around 0.1 inch in size (2-3 mm). If possible, use good sphagnum rather than dusty fine brown peat. I may have the names for "good" and "bad" peat moss wrong, see Dr. Dawg's article:
http://garden.org/ideas/view/d...

But I agree that perched water is likely to occur if the bottom of the soil area sits on top of something coarse. (Could you use the BOTTOM half of the pot for soil, instead of the TOP half?)

One gimmicky way to beat perched water is to finagle WICKS into the root zone so they are in good contact with the wet mix. (Perhaps kind of line the pot with toweling or Tee shirts before throwing in tin cans and soda bottles and what-not.)

A length of toweling is good, or a Tee shirt rolled into several layers, or big cotton socks. Over time they will get very funky, so don;t plan on re-using them!

Then trail the wick out of the pot and DOWN as far as you can dangle it. That down-hang adds the power of gravity to the capillary forces in the wick.

Where the wick touches the wet soil, it becomes as wet as the soil.

Because of gravity, the water in the wick "would prefer to be" in the bottom inch of the wick, and dripping off the wick.

So gravity pulls water out of the wick and drips it away.
Capillarity now pulls more water from the wet soil mix into the wick.
Gravity makers it drip away.

Now you have a "conveyor belt" pulling water out of the soil.

Air will still have a hard time diffusing through the medium, because there are no medium-size air gaps in the mix, only tiny gaps. So even after perched water drips out and the wick pulls even more water out, there are still very few real air channels allowing gas-in-gas diffusion.

Gas-through-water diffusion of oxygen is literally 10,000 times slower. But hopefully that's enough to keep roots alive.

Coarse, well-aerated potting mix is better than wicks!

(Articles I've read about soil talk about the air voids in soil or mix as "pores". They refer to "micro-pores", meso-pores" and "macro-pores".

Macro pores drain empty of water unless you hold the entire pot below water level. You expect macro pores to be full of air all the time. They keep roots from rotting.

Micro pores are so small that the capillary film on one side of the micro pore touches the capillary film on the other side. Micro pores will stay full of water until something like plant roots or a long wick actively PULLS water away from the capillary-sized micro pore. In other w3ords, micro pores stay full of water until the soil is SO dry that even capillary water has been pulled into the plant roots.

You can't rely on micro pores to aerate the soil since the only time they hold air is when the soil is almost dry enough to cause wilting.

Meso pores are in-between in size. They have capillary films, but the center of a meso pore will have some air and some water depending on how much you over water, how long its been since the last drowning, and how fast the mix drains.

If your mix only has hair-fine peat and powder and fines, all you have are micro pores and drowned roots.

If your mix is entirely 1/2 inch gravel, you have tons of macro pores and great aeration, but you would need to water almost continuously to keep a useful amount of water in the mix (drians too fast = does not hold enough water). Roots won't drown and die in that mix from lack of oxygen, the whole plant will wilt and die from lack of water.

But if your mix has coarse ingredients: COARSE sphagnum moss fibers and grit and Perlite and bark chips, say lots of things in sizes from 1 mm to 3 mm, the mix will have many meso pores where those coarse ingredients don't nest tightly together.

NOW you will always have some water and some air: the formula for keeping plants alive.




Name: Will Creed
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WillC
Nov 5, 2016 9:40 AM CST
With such a large container, all the excess soil retains water and holds onto it for a very long time and that often results in root rot. It is less about the potting mix and more about the pot size.

If it were my plant, I would take it out and pot it into the smallest container that the roots will fit into snugly with just enough potting mix to cover the roots. You can then set that small container in a larger container, if you prefer. Keep the roots tight.
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Name: Evan
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eclayne
Nov 5, 2016 9:52 AM CST

Plants Admin Emeritus

WillC said:If it were my plant, I would take it out and pot it into the smallest container that the roots will fit into snugly with just enough potting mix to cover the roots.

For all off the reasons Will mentioned this is what I would do as well. Also bear in mind that optimal conditions are harder to achieve at this time of year especially for what appears to be a Xanthosoma.
Evan
Virginia (Zone 7a)
Rez
Nov 6, 2016 8:51 AM CST
Thanks, I took it out of the large container and put it in one which is bigger than the original one it came in but not by much. It was bursting the put it came in when I bough it. Good lesson. I had killed another plant by moving it to a much larger container. The potting mix I'm using now is low quality. It contains lots of pieces of wood.

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