Throughout the recorded history of bonsai, many ways of covering the drain holes have been devised. Broken pottery, rocks, small animal skeleton rib cages, bamboo lattices, all tried and mostly failed. During the beginning of the Twentieth Century various manufacturing concerns learned how to take thin rigid material, and weave it into a screen. They then sold it to hardware stores, which in turn sold them to us.
With these screens there then developed a need for a a method of securing these screens into the pots. Many techniques were developed. But only one has risen to the top.
This post will demonstrate the “corrected” technique.
There was an engineer who, after exhaustive analysis of materiel and methods and, using 4 dimensional non-Euclidean geometries, employed a Cray supercomputer to crunch the data points until this method was proved.
First, we deal with the pot.

It is important that this pot have at least one drain hole. Otherwise, there would be no point. Right?
So if this hole (or holes) are not more than 2.324 times larger than the largest particle of your soil mix, you don’t need a screen. You see, the soil matrices and hydraulic surface tension will contain the soil within the chosen vessel without the need of an adaptive device such as the screen in which we are utilizing.

This nylon based, rigid, grid matrix construct is the item we shall use for this application. It is a product used in crafts generally called “plastic canvas”.
It is available in a multitude of hues and dimensions. It is most readily available at retail outlets throughout the world.
There is an “official” version sold in the finer bonsai outlets. It’s black in color and well nigh lasts forever.
The “plastic canvas” will last exactly 3 years, 2 months, 29 days and three hours. Right up to the time when you need it most.

This mesh is used for soffit vents. I use it often because it works.
One most definitely can use metal screening material.

But it’s rate of degradation is just slightly less than that of our nylon example.
Whatever screenage our intrepid bonsai hobbyist chooses, this individual must take extreme measures to secure said screenage into the pot so his choice is effective.
This, my friends, is the technique:

Take a length of wire equal to three times the diameter of the hole. (I will quit with the pretension pseudo techie jargon now. That was tiring. Fun,but tiring) make sure the wire is at least 2.5 to 3 mm thick. The thickness is important to keep secure the screen.

Make a loop.

Make a second loop in the opposite direction.

Bend the ends down over the top of the wire (this becomes important in a few steps,so bear with me).

Make sure the spacing is correct. It must be just about the width of the hole.

Push through mesh and insert into the hole.

Bend wire out.

Holding the two ends

Push on the center, from the inside,and apply outward force on the two ends (from the outside).
With the loops going over the top (as I instructed), and pushing tightly from the inside, the wire will put binding force on the mesh, helping to hold it in place.

If you put your loops going the same way (like this) the force will be lopsided and cause the mesh to slip in the direction of the loops. This will dump that expensive bonsai soil on your bench.

If you put one loop over and one loop under it will just create a pivot point and the mesh screen will spin. Dumping the soil again.
If you use just a “u”,the holding force of the wire is inadequate in securing the wire. It just doesn’t hold, man.
Plus it tends to break the mesh.
Which can get meshy….sorry, I know, that was bad.
Anyway, that’s that.
Now you know, and knowing is half the battle.

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