Why Not Have Many Tiny Drainage Holes?

[DrTolhur]

The standard form for bonsai pots is to have fairly large (quarter-ish sized) drainage holes with maybe some smaller wire holes. But then you need to put some kind of screen over the holes, and sometimes the drainage isn't ideal if there's only one in the middle. Why aren't bonsai pots made with more tiny holes all around the bottom, which would allow for more even drainage and also not require use of screens? It seems preferable to me, but I've never seen it, so I assume there's a good reason it's not done.

Does it not actually provide ideal drainage? Is it just too hard/time consuming to do? Would it cause the ceramic to break while firing?

(I've seen some of the training pots that have something akin to a combination drainage hole/screen in the bottom, but I've never seen it with ceramics, and even those still localize the holes rather than all over.)

 

[ShadyStump]

The standard form for bonsai pots is to have fairly large (quarter-ish sized) drainage holes with maybe some smaller wire holes. But then you need to put some kind of screen over the holes, and sometimes the drainage isn't ideal if there's only one in the middle. Why aren't bonsai pots made with more tiny holes all around the bottom, which would allow for more even drainage and also not require use of screens? It seems preferable to me, but I've never seen it, so I assume there's a good reason it's not done.

Does it not actually provide ideal drainage? Is it just too hard/time consuming to do? Would it cause the ceramic to break while firing?

(I've seen some of the training pots that have something akin to a combination drainage hole/screen in the bottom, but I've never seen it with ceramics, and even those still localize the holes rather than all over.)

I've often wondered this myself.
My only guesses are first, like you said, it has something to do with ceramic manufacturing, or second that it's fluid dynamics.
By fluid dynamics I mean the water as it moves through the soil in a shallow pot hits the bottom and then has to spread horizontally, thus spreading more evenly throughout the soil instead going straight through and out the pot, only soaking a localized section.

That's just my amateur reasoning. I would love to hear from our potters or the likes of @markyscott for their thoughts.

 

[leatherback]

There ARE pots like this. But not many.

If you make holes small enough to stop substrate from falling through, invariably you will get smaller substrate particles getting in and clogging the hole. Same with roots. This would very quickly create an effective dam, and your drainage reduces fast.

 

[Colorado]

Yeah I think it would clog way quicker.

 

[Kudo]

And also it will be more fragile and break easily depending on the size of the ceramic screen

 

[sorce]

Washing multiple dishes is so inefficient, I realized the other day we must do this still, gather all the dishes to wash later, because we never adapted from when we used to have to fetch water from a river or a well.

I reckon the truth behind the one hole is similar to this, like MOST things actually, we just never adapted from "what works".

The first pot would have had one hole and it must have worked.

Sorce

 

[jimib]

I have a plastic cart I roll a few of my trees in and out of the garage on during the “shuffle”. Sometimes it rains on it and the water collects so I drilled small holes to drain it only to find out the small holes got plugged easily with a single small piece of substrate. So I made bigger holes. I’m guessing a pot would plug up the same way.

 

[Bob Hunter]

I put plenty of holes can not have to many!

 

[Brian Van Fleet]

I put plenty of holes can not have to many! View attachment 423957

…until you’re cutting mesh screens and wire staples to cover them all…ugh.

 

[August44]

I just ran into this problem yesterday with a smaller larch that I collected 2-3 years ago. It did not do much last year, so I examined things and found that the soil was a little thickish (to many fines) and way to wet. It was an 8" round mica pot with one 3/4' drain hole in the middle with mesh over it. The thick soil was bad, the one drain hole with partially clogged screen was bad. Jerked the tree and raked out the roots. Lots of dead ones. Also drilled more holes in the bottom and put in better soil. Repotted tree. It's a dormant Larch...we will see.

I drilled more holes in some of my other mica pots also. Do they make a larger mesh screen than the one shown here?

 

[Brian Van Fleet]

Do they make a larger mesh screen than the one shown here?

Probably, but that appears to be the same mesh size I use and haven’t ever had problems.

 

[August44]

Probably, but that appears to be the same mesh size I use and haven’t ever had problems.

I think it's about soil particles and doing a better job paying attention!

 

[DrTolhur]

Why would small holes in the pot getting clogged be more of a problem than small holes in the screen?

 

[August44]

I think all the screens I have, or have seen are to small IMO. The ones I have are showing a 1/8" square hole, but only 1/16" actual hole size. I am going to try 1/4" hardware cloth which is 1/4" minus the wires, so less than 1/4" and much better draining. I have always used a thin layer of bigger substrate in the bottom to help with drainage.

 

[Deep Sea Diver]

Out in the Pacific NW lots of folks have been drilling holes in their pots for extra drainage. Also seeing pots “chocked” up during atmospheric river events and through most of spring is pretty much a normal thing to do out here

In the past year and a half I 3 contacted potters and asked then to start putting more holes in their pots, 5/16-1/4 in the four “corners” and oversized holes for the normal drain holes. None have said no, and all three started doing pretty much what I’d asked. A couple potters I know, Vicki Chamberlain and @sorce , have done this or more for years. So it doesn’t seem to be an issue with the ceramics side, more a deal with “Tradition”

Cheers
DSD sends

 

[andrewiles]

Yeah, I've been wondering the exact same thing. Here in the PNW October - April is basially one long sogfest.

In my nascent potting efforts I started adding more drain holes. In my next pot I'm thinking about moving the existing holes all the way to the edges and adding another row in the middle, for 9 total. This is 19" x 11" btw.

No idea at one point the strength of the bottom is compromised.

 

[Lumaca]

…until you’re cutting mesh screens and wire staples to cover them all…ugh.

Would smaller holes eliminate the need for screens though?

 

[penumbra]

Would smaller holes eliminate the need for screens though?

There are a lot of plastic bonsai training pots that have only small holes and are designed to be used without screen or mesh.

Do they make a larger mesh screen than the one shown here?

They do indeed for for a myriad of other uses and not necessarily made for bonsai.

 

[Deep Sea Diver]

Hobby lobby sells sheet mesh needlework material that fills the bill nicely. Multiple mesh sizes, multiple colors..

One can even get Christmas colors!

cheers
DSD sends

 

[0soyoung]

Get an ordinary kitchen sponge, one that is relatively thin and long (like an O-Cel-O sponge). Thoroughly wet it and lay it on its side (as a thin slab) on a wire cooling rack, say. After it has quit dripping, tip it up on edge.

There are several implications to what you will observe.

1. No amount of drainage holes will change the fact that there is a saturation zone in any substrate (one could repeat the experiment using a baking sheet, say, if need be to confirm this as fact)
2. The reason for tipping pots when it is rainy is the same as tipping the sponge on its edge (the saturation zone is a thickness measured up, against gravity).
3. So called drainage layers simply raise the position of the saturation zone within the pot (it amounts to putting another wire rack some distance under the wire rack in your kitchen sink experiment).
4. We can put maples in shallow trays because they can transpire the water from the saturation zone (in which their roots are totally immersed) before the roots drown. Pines, on the other hand cannot, so we must plant them in deeper pots to keep the roots from drowning (that is, place the roots above the saturation zone).

And when one thinks about it, transpiration is just evaporation from the leaves. Since this water was adsorbed by the roots, transpiration is effectively evaporation from within the volume of the substrate. Water also evaporates from the exposed surface(s) of the substrate. With a perforated container like a pond basket, water evaporates from the 4 sides as well as the top (evaporation from thee bottom depends upon the placement of the basket, on the ground, on a solid plank, or etc.).