Drainage layers. Do you use?

[Mike Corazzi]

I always have. Theory being that if ANYTHING decomposes, plugs up, goes bad,.......SOME water will make it to
a layer of coarse non organic chunks and migrate ....sideways if necessary.... and at least the bottom will get wet.

Judging from how roots will escape a pot for water, there's a good chance they will find a drainage layer to sneak into.

Maybe.

Correct me if you disagree.

 

[penumbra]

Right to some and wrong to others, like almost everything else.
I use a drainage layer only in deep pots for cascades and semi-cascades.

 

[Paradox]

Used to
Don't any more because of discussions here about the effects of them and behavior of water in a pot

 

[Mike Corazzi]

Used to
Don't any more because of discussions here about the effects of them and behavior of water in a pot

Yeh, I know. That's why I'm asking.
Hyuga was a mistake.

 

[ABCarve]

I put a small mound of large pumice over the drainage holes which does a good job of keeping roots from growing into the screen and clogging the hole.

 

[weetree3]

I put a small mound of large pumice over the drainage holes which does a good job of keeping roots from growing into the screen and clogging the hole.

View attachment 458345

Nice tree!

 

[penumbra]

Nice tree!

Even downside up.
Looks like reflection in water.

 

[Clicio]

Yes, mostly to add weight to the pot and keep the drainage holes from clogging up. No issues whatsoever up to now, after 7 or 8 years using it.

 

[RJG2]

Not in bonsai pots - but I may try @ABCarve's method for faster growing things in the future (hard prune the roots of forsythia in the spring and you might need to repot again in August...).

I do in Anderson flats and nursery pots, but just so the smaller particles don't fall out.

 

[amcoffeegirl]

I never heard this until a few years ago.
I do not do this. There are times in shohin or name where I might put a fine layer on top but it never stays there long. Usually I just go for a consistent mix.

 

[Mikecheck123]

A proper substrate doesn't need a drainage layer--it IS the drainage layer.

 

[Potawatomi13]

Many drainage holes needed first then add drainage of coarsest pumice not used after sifting. Believe have seen Ryan Neil use in repotting videos so not bad idea.

 

[bbk]

You’d be better using washed river sand or similar than a course pumice/ gravel etc if you really want a “drainage layer”

The problem with using a larger aggregate is that smaller material just clogs up the gaps and you end up with a more dense material, and therefore less drainage than because the remainder of the material is solid.

I speak from an engineering perspective, not a horticultural perspective. ie I am not making a comment on what is best for the plant, just that it isn’t a drainage layer.

 

[Brian Van Fleet]

The deeper the pot, the more likely I am to use a coarse layer of soil at the bottom.

 

[Clicio]

The deeper the pot, the more likely I am to use a coarse layer of soil at the bottom.

Ditto.
Shallow pots for acers, for instance, I have been using only my regular mix.

 

[Leo in N E Illinois]

no drainage layer. The more uniform the particle size the better the media breathes and allows water through. This holds true regardless the size or depth of the pot. In tall cascade pots I have filled the lower layer (half) with coarse media, then put a piece of screen to keep the media separate, then filled the upper half with the media the roots will actually be growing in. This was for tall Chinese style cascade pots. Current fashion in cascade pots is roughly a cube, and then use a stand. Here I use a uniform media.

 

[Emeraldtarpon]

Will never use in bonsai pots (except for a tall cascade pot).
Starter material grown in standard plastic pots...yes.
Starter material grown in squat pots...no.
I tip my pots sideways to drain and it fully disperses the excess water in the soil...whether its been lifted in the pot, due to drainage material, or not.

 

[penumbra]

In tall cascade pots I have filled the lower layer (half) with coarse media, then put a piece of screen to keep the media separate, then filled the upper half with the media the roots will actually be growing in.

This is precisely what I have done.

 

[Paradox]

I guess if I had a really deep cascade pot or even a semi cascade, I might put some larger material in the bottom

 

[bbk]

no drainage layer. The more uniform the particle size the better the media breathes and allows water through. This holds true regardless the size or depth of the pot. In tall cascade pots I have filled the lower layer (half) with coarse media, then put a piece of screen to keep the media separate, then filled the upper half with the media the roots will actually be growing in. This was for tall Chinese style cascade pots. Current fashion in cascade pots is roughly a cube, and then use a stand. Here I use a uniform media.

Your point about a uniform particle size is really is really the key issue.

Look up rock density by particle size. It makes no difference.

If people are using “drainage layers” why, other than it “seems like a good idea”?

It sounds to me, even if you use a screen to separate the growing medium and presumably the roots from the “drainage layer”, what purpose does it serve?

Once the roots have taken up the whole pot or to the point of the “drainage layer” it needs to be repotted.