Would holes in the sides of plastic pots impove drainage and aeration?

Question

Since the pots are plastic, they are not breathable. I made enough holes at the bottom to let the excess water seep out.

Some time ago, I made some, 1/4 of an inch, holes.

But when I watered it with nothing in it, some of the water was retained along the sides(since the bottom is slightly curved inwards). So I made some more, even smaller than 1/4 of an inch, holes. Now much of the water is removed, but not complete. I will show some pics:

More holes I made(looking inside the pot):

Water retained(I hope it is clearly visible):

Now comes the aeration/breathability. Should I make any holes on the side of the pots? If yes,

1. How many?
2. How much bigger/smaller
3. In what manner(refer to final pic with four pots with yellow dots that represents holes of diameter smaller than 1/4 of an inch)?

Should I even bother? Will that be good or bad for my plant and soil?

Answer 1

No, don't bother, it absolutely is not necessary and not a good idea either. Just use the pots as they are - the fact that a little free water is sitting in the bottom of the empty pot in your image isn't an issue. People have been growing plants in plastic pots for decades (including me) without creating 'aeration' holes in the sides, and the plants are just fine. If you did put holes in the sides, as soon as you tried to water anything growing within, it would be pouring out of those holes before the water's had a chance to be taken up by the plant.

Answer 2

I'm going to go with "it depends.". If you are trying to grow cactus in England, perhaps holes would help. If you are growing a tropical plant in Arizona, probably not useful.

I have used both terra cotta and plastic pots for cactus in Arizona and I add holes to the bottom of both types.

So, it really depends on what you are growing, what potting media you are using, local weather (humidity, rainfall, temperature, watering, etc.)

Pot moisture retention is a function of both the pot and the potting media. If you have a plastic pot and an absorbent media, it will retain water. If you use a more porous/less absorbent media and a terra cotta pot it will disperse moisture more readily.

In Arizona, I'm trying to retain moisture so I add a layer of top dressing to the soil which keeps the moisture from just flying away.

Answer 3

A point which might be relevant in this context is that holes in the side might well, in humid circumstances, encourage root growth outside the pot. When mature these roots could make it very hard to knock the plant out of the pot, say to pot it up to a larger size. In a commercial context anything that slows operations down is not welcome.

When you water a potted plant initially the water will displace all the air around the roots; then as the water drains away it will pull fresh air into the root ball behind it from top down.