About a couple of weeks ago, our local Wal-Mart offered black fabric reusable shopping bags for $0.88. The idea is to keep taking the shopping bag to the store to reduce our dependence on oil and wood pulp. The bag is made in China from polyester (PET) from recycled soda bottles. I tried to fill the bag with water and found a good rate of drainage. Unlike commercial "root control bags" or "smart pots", the reusable grocery bag does not have a circular bottom. The rectangular bottom is longer than wide, which means that once it is filled with soil and packed down, the top of the bag will round out while part of the bottom will flare out. The bottom portion which would flare out could, with a little practice, be folded before filling with soil, to yield a more circular bottom. Another possibility is to fold the flaring flap upwards and secure with a safety pin.

About a month ago, another mega store in the pacific northwest, "Fred Meyer" began offering reusable grocery bags. These are also made in China, but with black fibers of polypropylene from recycled bottles. The first time I filled one with water, drainage was quite slow and limited to the stitching at the bottom. Unlike the Wal-Mart bag, these bags have a thin semi-rigid insert. After removing the insert, drainage through the porous bottom panel was now sufficient, and even faster if I added a small squirt of mild shampoo. To get a symmetrical pot, the bottom of the grocery bag will have to be folded as is the case with the Wal-Mart bag. Fred Meyer gets their bags from Earthwise, the link is below. I know of no website for the Wal-Mart bag.

The fabrics of either type of bag seem strong enough to make a pot. The polypropylene fabric of the Fred Meyer bag seems a little more substantial. I have no idea of the UV-Resistance of these bags, but I assume that the black pigment will yield enough protection for at least one growing season.

The fabrics are sufficiently porous so that the soil should be more oxygenated than a pot made from solid plastic (these bags should be similar in soil volume as a standard #2 or #3 nursery pot). It is not clear to me as to whether the fabric of these grocery bags will force roots to develop massive feeder branches, which is the main advertised virtue of the commercial "root control" pots.

Both bags are made from recycled food-grade plastics. That would be fine, but I have no idea of how well recycled plastics are cleaned and if anything contaminates them. There is recent controversy as to whether food or soda bottles made from PET release excessive amounts of Terpthalate, a precursor (and degradation product) of PET plastic. For example, some baby food companies switched from glass to PET, and then switched back from PET to glass! Terpthalate can mimic human steroid hormones; it isn't a toxin, carcinogen, or mutagen in any classic sense; but since Terpthalate mimics hormones, it could lead to very subtle changes in how humans interpret their genetic code. This would only be a potential concern with the Wal-Mart bag. Terpthalate should be biodegradable and I assume that any microbes in the potting soil would keep terpthalate at a low level. If you use sterile potting mix, it would be safest to add organic fertilizer and then let microbes from the air get established before planting. Anyway, it is my intention to assume that any contaminants of recycled plastic, or any terpthalate release, will be at a safe levels, so I plan to go ahead and try these bags in the near future. (If you can't tell yet, my interest is in growing veggies.)

Here is a link that might be useful: Earthwise Reusable Grocery Bags (Fred Meyer's Bag)

At about $1 per bag, one would think that fabric grocery bags would be THE ANSWER. Yes....BUT...I want fabric pots that are bigger than #2 or #3. Something like #5 to #15, and even higher. The price of "smart pots" isn't the only thing that bugs me... I also want the pots to be deeper.

Erosion Control Tubes from FarmTek, (link below) may be used to make fabric pots. You get a knitted plastic tube, either 12 or 16 inches in diameter, by 10 to 100 feet in length. You would cut your roll into segments, perhaps 18 to 36 inches in length. You could make a bottom by twisting and tying off one end (this would shorten your segment). Then fill with soil from the open end and pat down. While commercial fabric pots usually have a smooth and elegantly constructed bottom, the twisted bottom of a modified erosion tube would be bumpy, but not too obvious once the soil is packed down and sides of the tube are pulled up to provide tension. One could also sew or glue one end shut, so that it would look more like a sandbag with a flaring bottom and circular top. In the latter case, the bottom segments which flare could be folded underneath before filling with soil, or folded up and secured with a safety pin. Thirdly, one could sew on a circular bottom. Sewing seems like a lot of work, I would prefer to twist, tie, and pack the bumps down.

Erosion control tubes are usually filled with pea gravel, bark or straw; and they are used in construction sites (eg roads) as dams to intercept flows of muddy water (eg., rain flowing down a dirty slope). The mud gets trapped by the filling, and cleaner filtered water exits the bottom of the dam. This means that the plastic has to be porous. Obviously, soil in a pot made from an erosion control tube would be more oxygenated than that in a solid plastic pot. It is not clear to me whether this fabric will induce roots to branch into a mass of feeders.

The web site says the bag is made from knitted polyethylene, so it may be more similar to shade cloth than a woven sandbag, and perhaps belongs in the "meshy" subthread. The description specifically claims a high level of UV-Resistance, but no lifetimes are given (no definition of what "high level" means).

Here is a link that might be useful: Erosion Control Tubes from FarmTek

Oops, I forgot to mention how much a pot made from such material would cost. Not counting shipping cost or DIY labor, a pot equivalent to a #7, #10, or #15 should be about $2-$3 a piece.

Plastic sandbags, analogs of burlap sandbags, are made from thin flat strands of polyethylene or polypropylene woven into a mesh; perhaps 10 to 14 strands per inch per direction. The pores of the mesh are small, so sandbags aren't all that "meshy", but the pores are large enough to let water and air flow through. They should oxygenate the soil better than solid plastic pots, but I don't know if they would force root branching.

The UV-Resistance of sandbags varies. White (or translucent "natural") bags often have a rating of 200 hours. Colored (and some white) bags often have ratings of 1200, 1600, or 2000 hours. I couldn't find a website that had a rigorous definition of "UV rating" - whether these are hours under sunlight or hours under an accelerated artificial UV lamp. If the best of these bags only last 2000 hours under sunlight; that is less than one year! Note that engineers may want sandbags to fall apart quickly -- soon after a flood; they don't care about us! 2000 hour sandbags can be found on ebay in reasonable quantities for about $0.50 a piece; not bad for a large pot!

Dayton Bags offers a sandbag with enough UV-Inhibitors to last several years. These bags are constructed differently than above: plastic films are laminated over the bottom and top of the middle woven layer. In other words, these are made like a waterproof coated tarp. These would not be porous and offer little or no advantage over solid pots in regards to soil oxygenation.

Dewitt is one of the major players in the landscape fabric market. They offer non-woven fabrics (felt-like) that block weed growth. They need to be buried under gravel or mulch. Dewitt also offers woven weed-blocking fabrics that don't need to be buried (tarp-like, sometimes with felt-like backing on one side). Either type of weed-blocking fabric needs to be porous, or the landscape would be flooded; but not too porous, or weeds will come through. The woven fabrics are said to be "needle-punched", whatever that means. Dewitt makes sandbags, apparently from one of their woven needle-punched landscape fabrics that doesn't require burial. They are advertised as UV resistant, but no lifetimes are given. Dewitt's website menu has a dead link to any description of their sandbags. They are about $0.50 a piece and available in small packs; I'm going to go for these! I'll report back in a few days to weeks.

If you go to a landscape supplier of rock and boulders, you may observe that rocks are often packed in giant bags constructed of tarp-like material (giant sandbags, but with more elegant bottoms). This tarp material may be uncoated (like most sandbags) or coated. I assume that the rock bags are uncoated as I have never observed pools of water in such bags. Either that, some of them have "bottom shoots" that may leak water. In any event, if these are used as giant pots (100 gallons and more), one may prefer the uncoated if you wish to oxygenate the soil. Otherwise, I see no advantage of coated super sacks to the largest solid plastic totes made by Rubbermaid or Sterlite (these even have wheels!). It is obvious that those particular models of super sacks used to transport landscape rock must have UV-Inhibitors, but I don't know how much. Allmost all websites describing super sacks usually don't have price information, or if they do, they are for packets of hundreds to thousands.

Google "lawn bagg" (sic!!!!) and you will find super sacks sold to gardeners for use as garden waste bags (eg., fallen leaves). I don't know if these are uncoated (air and water flow) or coated (waterproof). They have enough UV-Inhibitors to be guaranteed for one year; but are likely to last longer. Price is ridiculous; giant wheeled Sterlite or Rubbermaid totes from Wal-Mart are cheaper. If "lawn baggs" were offered at large discount when purchased in small packs, I may go for it even if they are coated, as an alternative to raised beds.

I wrote:

> For example, some baby food companies switched from glass to PET,
> and then switched back from PET to glass!

I was confusing "polycarbonate" with "PET". Polycarbonate contains traces of "bisphenol-A" as a precursor and breakdown product. PET contains traces of the precursor and breakdown product terpthalate. Bisphenol is the mimic of steroid hormones.

So I won't worry about wal-mart bags.

I received my order of UV-resistant green sandbags produced by DeWitt. I thought that it would be the same polypropylene fabric that they use as a weed barrier; but I now doubt it. In other words, I expected a small hole (for water drainage) at each cross weave (the "thread" is about 1/8 to 1/12 wide, flat, and thin). Water drains quite well through the stitching at the bottom of the bag. In contrast, drainage from the fabric wall is slow. Water leakage through the fabric is best observed if a jet of water from the hose is aimed at the wall; otherwise, leakage from the wall only by gravity is slow and rare.

I can't tell if the fabric has a thin film laminated coating. The surface of the fabric is smoother than I expected if there was no lamination, but more water drains out than I expected if there was a laminated coating. In no way is any possible laminated coating present on the DeWitt bag similar to that pictured for the long lasting sandbags offered by Dayton Bag Company.

Making pots out of these sandbags would involve folding the bottom, and securing such folds with a few dabs hot melted glue. These would be loose folds to form a more cylindrical bottom, just strong enough to make it easier to fill the bags with dirt. UV-resistant hot glue sticks are available (I don't know where), but since these will be in the bottom of the bag, shielded from UV by dirt, sticks from the Craft section of Wal-Mart should be fine. Since such pots would be too tall given their diameter, the tops could be rolled inside out, to reduce the height.

I'll go ahead and make some pots out of a few of these, since I got them anyway. But I can't really recommend them at this point: First, I doubt that any pinholes in the fabric are large enough to cause roots to branch. Second, I don't think that the oxygen diffusion rate through the bag would be that much better than a solid plastic pot. I previously suspected the first, but I was really hoping for a much improved oxygen situation. If you are currently a user of pots made from black plastic film (these have holes in the bottom, otherwise they are similar to normal plastic bags, except that they are sold as nursery pots); these DeWitt sandbags may be competitive.

It is possible that if I subjected these sandbags to a small amount of wear and tear (as a transport bag), the fabric will loosen up and become more porous for oxygen. In which case, I would post an update.

Here is a link that might be useful: DeWitt Sandbags

I wrote:
> the "thread" is about 1/8 to 1/12 wide, flat, and thin

That should be "...1/12 to 1/8 INCH wide..."

For readers outside the USA, that would be 2 to 3 millimeters wide.

I have not measured the thickness, but a quick glance by eye indicates that it would be less than 1/10 mm.

It sounds like the sandbags y'all are talking about are similar to the rice bags we have here. Rice bag gardening has been taking off here as food prices skyrocket (we have 20% inflation or thereabouts per month currently). I'm just getting into doing container gardening, so have no personal experience to share as of yet, but plan on using rice bags in the 5 and 10 kg sizes for the most part.

I assume that sandbags in the USA are probably similar to your 10 kg rice bags. Our sandbags vary in regards to their resistance to sunlight. In some cases, exposure to as little as 200 hours of sunlight triggers their degradation (they become very brittle), while others survive over 2000 hours. Please report on how long your rice bags survive.