Does anyone know why some growers tip their trees for "water runoff"?

I have read about some bonsai growers who recommend tipping bonsai during heavy rains, sometimes during the winter, and they say it is "...let the water run off the soil surface to avoid saturating (I think) the trees....."
For years I thought "...interesting...I wonder if this works?..." Anyway, I then had this thought "...wouldn't a tipped pot allow for water to accumulate at the end of the pot and ...end up soaking/saturating the roots at the bottom; in effect you would be drowning half of the roots in the pot....just the opposite of what you're trying to prevent?" Just a thought...
Does anyone have experience with this procedure, who could shed some light on this? Thank you for any thoughts or help on this. Regards, Todd

Although I have never heard of or tried this technique you logic seems very solid. Unless there is a drain hole right in the corner toward which you tipped the pot you would end up with some pooling of water. I also think that the run of would take with it some of your soil/substrate and create a soil unevenness that would have to be fixed after every heavy rain. I would think that the drain holes would provide enough runoff. Sorry I can't give you more information but I just wanted to backup your thought process.

Todd

I do it with some trees that are very sensitive to wet feet, such as some japanese maples. It works. The water comes over the rim.

My understanding was that it focuses the collection of water inside the pot to a more concentrated area in the lower corner of the tilted pot and therefore more water drains faster out of the hole nearest that collection point. I have also seen people stuff a cotton rope wick for the same purpose with good results.

It's a matter of physics and chemistry. A porous medium will support a column of water the height of which depends on the structure of the medium. A uniform coarse porous medium will support a shorter column than an uniformly dense one. The number and size of drainage holes don't matter, the column height will be the same irregardless. This means there is ALWAYS a saturated level of soil in the bottom of the pot after watering and initial drainage. For argument, let's say it's 1/4 inch. For a large shallow pot, this 1/4 inch saturated layer of medium will cover the entire bottom of the pot. Now take a tall narrow pot of equal volume and fill with the same medium. It will have the same 1/4 inch saturated layer in the bottom, but area will be greatly reduced and thus thus the water stored this way in the pot will be proportionately less.

By tilting the pot, even slightly, there is a smaller volume of soil that will be saturated and the excess will run out until the 1/4 inch equilibrium is reached again. A simple experiment you can do in the kitchen: Saturate a sponge, and without squeezing it, let it lie horizontally on your hand until it stops dripping, then tilt it vertically and watch how much water comes out.

Brent
EvergreenGardenworks.com

That makes alot of sense to me. Thank you for the explanation. Regards, Todd

Nicely explained Brent. I remember a discussion of this here years ago where this characteristic of water was referred to as "perching". It was caused by surface tension and the height was dependent upon particle size of the medium. By tilting the pot you are temporarily converting it from a wide shallow one to a tall narrow one.

And, if you're worried about the quarter inch of waterin one end of the pot, merely tip it the other way every day or so.

We get so much rain here, my trees often look like drunken sailors on the tabletop as they tilt this way and that.

That was well explained Brent but it was basically what I said so I would like to award myself the laymen terms award.