It's nutts. ;o) Why make an effort to absolutely guarantee anaerobic conditions in the pot bottom? Invite the author here - there are a few dozen people he/she should meet? Lolol

Al

There's a point in putting the holes at the very edge: if the planter is sitting directly on the roof it is easier to drain. But I'm talking 1/8-1/4 up where the container starts curving up. And I'd still drill 1 or 2 small holes directly underneath.

I ended up drilling holes around the sides immediately after a rainstorm that flooded the plant with roof overflow. Standing water on top of a container doesn't really help aeration: particularly in a compost/peat based soil

Thanks for the help. I'll put some holes in the bottoms and on the sides too.

Bill

castorp, I have grown tomatoes and herbs quite successfully in "Earthboxes" which have a reservoir in the base and an overflow opening on the side. There is 'wick' composed of the potting medium contained in a tube which dips into the reservoir. I would fill the reservoir until water came out of the overflow opening. At first the interval was maybe 3 or 4 days. As the plants matured and bore fruit, expectedly, I had to do this almost daily.
Elsewhere there is the "Lechuza" planter. Apparently one has to top water the plant for a lengthy period to tempt it to send its roots through a layer of supplied medium, then through a perforated plate and into the water reservoir below. Thereafter, water is supplied into the reservoir as indicated by a floating indicator. They do recommend that the plants be 'dried down' in what I interpret to be a cyclic program.
My conclusions from all this? If one is doing subsurface irrigation, the medium must permit water movement upward. Depending upon the plant this movement upward may need to be limited. The tomato plant prefers a free draining soil and it readily sends out roots from the stem near the base. I found it useful to have a pretty coarse mix in the top six inches of the "Earthbox". Moulding up of tomato plants in the ground takes advantage of this rooting habit.
Finally, long ago and far away, we constructed a crude hydroponicum to grow sugar cane plants from cuttings. The cuttings were held in holes in a cardboard cover over the container of nutrient solution. The first cuttings all rotted because we had neglected to provide aeration. Thereafter we always left a space in which roots developed to provide that all important aeration.
I guess that this is a good point to stop.

I think I'm just going to make these barrels into regular old u-water containers--especially since I've already started drilling holes. But I'll hang onto the self watering idea. Thanks.

Bill

Practically speaking, there is almost no difference between drilling holes on the side of the container to create a water reservoir and allowing a planting to sit in a saucer of drainage water ....

Al

Usually the saucer is there to catch the water which drains away (gravitational water) from the pot. But a saucer can function as a reservoir when one is unable water a potted plant at the optimal time. I had a personal struggle with a Spathiphyllum until I was advised to place it in a deeper plastic saucer. When I watered it, the saucer held enough water to supply the plant's needs until I could get back to it. I am sure that issues of salt accumulation and root rot will crop up. Both the "Earthbox" and other sub-surface irrigation containers appear to limit how high the water will move up in the medium and they provide for adequate aeration.
From what I understand, a critical difference between European and North American interiorscapes is that the former plant directly into water tight containers while the latter sit the grow pot in a saucer inside the decorative container. This saucer is regularly monitored. I have no idea how the European system is monitored to head off water logging.
To quote the King "Is...a...puzzlement!!!"

Ronalawn,

By European system are you referring to hydroculture? If so the plant's roots are usually above the level of the water.

What works for me is to drill a 3/8" hole on the side 1 " from the bottom, then another hole 1" up from the first hole ,then a third hole another inch up and use 3/8"x1" bolts to control the moisture in the box,i never put holes in the bottom. Here in tex. july is really hot and this method works great for me. In july and august i usually have the bolts in both bottom holes .Give it a try, it works for me.

I am thinking of holes on the sides vs bottoms of my new water troughs--to prevent invasion of tree roots= the main reason I am switching from wood raised beds in the first place!

That's fine as long as the bottom of the drain hole is flush to the bottom of the pot. If you have an arrangement like "billtex" described in his post immediately above yours, you'd be asking for a problem.

In order to eliminate issues with perched water in your troughs, you could leave 1 or 2 wicks hanging out of the drain hole and tuck them under the troughs when you set them on the ground. What large city is near where you live? What plants will go in the troughs and how large are the troughs?

Al

Txs for your feedback, I have ordered two 6 foot and one 9 foot. The wicks might be a good idea too. I plan to also perch them up on bricks over layers of landscape material so there is both a barrier and an air gap underneath. I live in Toronto Canada and my maple tree roots are just so invasive in my wood-raised beds. They are literally strangling my perennials.

The wicks will need to be in contact with the soil if you're looking for the kind of drainage you get in a raised bed as opposed to a container. From the perspective of hydrology, the wick will be what determines whether you're growing in a raised bed or a container.

Al