If your screen is semi flexible then it won't distribute the weight well and may collapse in places.

While some will disagree with me, it isn't at all necessary to prevent roots from growing into the water reservoir. None of the commercial units prevent this.

Also, you don't need any aeration holes in the container. The overflow hole just above the water level is sufficient for this purpose. Some build them into their homemade designs thinking this will allow more oxygen to the roots, but it won't, it will only lead to faster evaporation of the water.

There are others who can advise you as to specific material choices and their pros and cons, my purpose was simply to try to assist you in understanding the concept of a self watering container and dispel a myth or two to aid you in your design.

My screen is somewhat flexible, but is about the flexibility of hardware cloth, so fairly rigid. I did think about flex and that's why I am going with the five wicking baskets below to try and minimize that (four didn't seem like enough). It seemed like the overflow hole should provide the airflow without the need for the additional airflow tubes, so thanks for explaining that more throughly. The only reason I chose to use the landscape fabric is that these are longterm plantings (blueberries and raspberries) and neither apparently likes wet feet, so I thought it best to try and prevent the roots from getting down in there. Maybe it's not necessary. It sure would have saved some money not to have to buy the fabric considering I don't need a whole lot of it. I probably have a lifetime supply now and I bought the smallest quantity I could. We'll see what kind of success I have with the plants.

My guess is that if your raspberries do well in SWC they will destroy the landscape fabric in short order. The blueberries I doubt will as they have fairly wussy/shallow root systems ;)

Landscape fabrics (that allow water air through) are designed to prevent the top growth of plants from getting through, but are not designed to prevent roots getting through. A root starts off with an impossibly tiny diameter and will find any opening no matter how small and grow through it and then expand.

Still, no harm in stocking up on something. I am sure you will find a use for it down the road. I have a shed full of stuff I will find a use for eventually, I hope ;)

To try and better explain why I do not consider it necessary to prevent roots from growing into the water reservoir I will offer this explanation:

What is the absolute worst thing that can happen if the roots grow into the water? They die. In most cases they won't, but that would be the worst case scenario.

If the roots want to grow deeper, but can't due to a blocking layer, what is the absolute worst thing that can happen? The roots grow around the container in a spiral of death. At first it is no big deal, but then they start constricting and choking each other and become useless. They die :)

The end result is the same. The difference is that many plants can adapt their roots to take advantage of the water while none can adapt to overly constricted roots.

OK, well I guess that makes sense.

I beg to differ on the overflow hole.

You need one. Or actually a couple. Even if it is only a 1/8" drill hole.

Think about what happens if you get a torrential downpour. My memories of Texas is that a good part of the year you get heavy thunderstorms interspersed with droughts.

You need a couple holes right at the soil line. Or one a fraction above and one a fraction below. This drains standing water on top of the soil.

Then you need another drill hole right below the top of your reservoir. This deals with issues with overfilling. And with the heavy rainfall soaking through your soil.

I spent a good amount of time with my containers tilted to the side letting the water drain out or bailing the water out. Soaked and then ruined a pair of pants that way. Plus all my tomatoes split. That's not supposed to happen in a SWC.

For a drainage screen you might want to consider using the lid of the container. I tried cutting off the rim so it would sit inside. Then I drilled holes around the sides at the same level and put nuts and bolts in them so the end of the bolt supports the divider. Then have the wicking container in the middle help support it as well.

Alice

If it is a true half barrel size, then your yogurt cups and screen will collapse in no time once the soil becomes wetted. I would look at using something like a light panel cover (Some call them egg crate panels) HD and lowes sells them for about 10 bucks each. Cut it so that it wedges itself in. Cover that with your fabric, and use a couple of the yogurt containers as your wicking chambers.

Or if you can find PVC peg board, use that. I'm going to try and find some for some window boxes I am making this year.

I beg to differ on the overflow hole.

You need one.

I think you may have misread. I don't recall anyone saying an overflow hole wasn't needed to prevent the water from rising into the growing area, just that extra holes for aeration are not required. Overflow holes-yes. Aeration holes-won't make any difference other than to the rate the water evaporates.

Ok. Must have been sleepy while reading your post because re-reading it makes perfect sense now. :-)

I have heard other people advocate not using overflow holes so I guess that is why I got confused.

The instructions with the Gardener's Supply SWC's said only put an overflow hole in if you are outdoors. I've got two of their containers and the water level gauges don't work very well.

But regardless of the overflow hole I'd still say add a hole right at soil level.

I think I'm going to try the plastic coverings this year. I get a lot of overflow from the upstairs balcony so maybe that will help.

Alice