1. What are Self-Watering Containers (SWCs)?
'Self-Watering Containers' is a misnomer, of course. Containers cannot water themselves! SWCs are containers, meant for growing plants (or modified for use as such) usually with a bottom chamber that is a water reservoir, and with a top chamber that contains the potting mix and the roots of the plants. The roots draw up water through a process of osmosis. The plants, thus, always get enough water and never too much. Because of this, vegetables (and some, but not all herbs) grow much better in SWCs than in traditional containers. There are other advantages to growing vegetables in SWCs rather than traditional containers - these advantages are discussed below.
2. Where do you get them?
You can buy them or make them. One popular commercial brand is The Earthbox. (See: http://www.earthbox.com. ) I have seen Earthboxes in a local store; the pictures don't do them justice. They are quite good-looking.
Gardener's Supply Company sells a variety of very pretty SWCs. (See: http://www.gardeners.com.)
A Garden Patch also sells them, and theirs are the least expensive full-size SWCs that I have seen. (See http://www.agardenpatch.com/.)
Please note that I do not have personal experience with any of the commercial SWCs; we made our own.
You can find clear directions for building your own SWCs here:
We used the directions above, changing them only in that we used plastic colanders from a dollar store instead of pond baskets. We used 18-gallon Rubbermaid-style storage tubs for most of our SWCs, and round large tubs with handles for a few of them. Each container cost us about $10 to make.
Once you grasp the principles of this method of construction, you can make SWCs out of many different types of containers, including kitty litter buckets and 5-gallon buckets, which are, of course, smaller than the 18-gallon storage tubs but will serve nicely for a pepper plant, one of the smaller varieties of eggplant, and other plants. If you have a cat, the litter buckets are 'free' and people can sometimes get 5-gallon or similar buckets free from delicatessens, supermarket bakery departments, sandwich shops, doughnut shops, etc.
A detailed manual demonstrating how to build a variety of SWCs is found here:
(I recommend that you save these two sets of directions on your own PC if you are interested in making SWCs. URLs for both sets of directions have changed recently and could both change again or be taken down altogether. Both URLs work as of 2/10/08. I will not be updating this page if they change; save them if you think you even might need them.)
And for an SWC with a slightly different twist:
(Scroll down to pages 6 and 7.)
Also, see http://www.instructables.com/id/Building-your-own-Earth-Box/. Instructables.com has some other types of SWC as well. You can search Instructables.com on "Earth Box" and on "Self-Watering Container."
3. Why would I want to use SWCs?
- If you are growing vegetables in containers anyway, then the SWCs make life much easier: you only have to water every few days rather than every day (or even multiple times per day in the case of large plants in traditional containers).
- An even-better reason for using SWCs rather than traditional containers is that the vegetables grow very much better in them. I'd say that - per square foot of container surface - SWCs give you at least twice the yield of traditional containers, and probably even more.
- SWCs also conserve water; little to no water runs off, and very, very little evaporates since you cover the surface with plastic, or other, mulch.
- Using organic fertilizers is problematic in traditional containers; the traditional containers need watering so often that you are usually flushing organic fertilizer (which is slower-acting than chemical fertilizer) out of the soil before the plants can get the nourishment they need from it. But with SWCs, the fertilizer you put in the soil stays there and the plants can fully utilize it.
4. Are there any disadvantages to using SWCs?
Well, obviously, you have to make or buy the SWCs. Each container cost us about $10 - this can be a significant cost when you make a lot of them. When he made the first one, it took my husband about half an hour. He later easily cut that time down to ten minutes per container. If you buy them, they are considerably more expensive. I don't see any other disadvantages at all (assuming, that is, that you are going to be growing vegetables in containers of some sort rather than in a raised bed in the ground).
SWCs are, so far as I know, suitable for all vegetables. They are not suitable for many herbs and some flowers, which need drier conditions.
5. How do I use SWCs?
For the purposes of this report, I need only say: Read Ed Smith's book entitled "Incredible Vegetables from Self-Watering Containers: Using Ed's Amazing POTS System" and follow the directions in the book. Amazon has both new and used copies of the book. If you are fortunate enough to have a local bookstore (we aren't), then you'd probably prefer to buy the book there. Or maybe you'd prefer to read a library copy first to see if you want to buy it.
The book's details (from Amazon):
Incredible Vegetables from Self-Watering Containers: Using Ed's Amazing
POTS System, by Edward C. Smith
Paperback: 272 pages, (There is also a hard-cover edition.)
Publisher: Storey Publishing, LLC (January 1, 2006)
Product Dimensions: 10.8 x 8.5 x 0.6 inches
Smith discusses potting soil for use in SWCs, means of supporting floating row cover or clear plastic using an SWC, how to easily water them, and a lot of other important aspects of their use. But the main part of the book is a directory of vegetables, herbs, and edible flowers, giving growing tips and instructions for each one.
Some herbs and flowers don't like the constant moisture plants experience in an SWC, and Smith tell you which ones not to grow in an SWC. This too is very useful information.
Smith does *not* tell you how to build an SWC, but I have given URLs above that cover it.
I had worried that I wouldn't be able to grow a very large (indeterminate) tomato plant - plus its cage - in an SWC. But we answered that question last summer when we grew six full-sized indeterminate tomatoes in SWCs. We used rebar mesh cages; we just set the cage on top of the soil in the SWC as we would if it were in the ground. I had been apprehensive that they would tip over from the weight of the plants plus cage. The plants reached the roof of our hoophouse (8' feet from the ground) and started back down. None of them tipped over. All the tomato plants grew very, very well. So this was a non-problem.
We grew many different kinds of vegetables in the SWCs; all did very well indeed. We had 22 SWCs in use last year; we're making more this year.
I'd like to repeat that my harvests were far greater using SWCs than using traditional containers. The plants just amazed me by how splendidly they grew in SWCs. My vegetable plants were every bit as beautiful and healthy as the plants in the photos on this page: http://www.agardenpatch.com/pages.php?pageid=68
I would have liked to have written a more detailed report of our experiences growing with SWCs, but I have not found enough time yet; so this will have to do for now. I don't want to delay it any longer Maybe next winter I can get a more detailed report completed - and then I'll have two seasons' worth of experiences to write about.
10 February 2008
Update of 20 July 2008: We're well into our second year of growing (mainly) in SWCs and I'm even more impressed with them. They are fantastic - if you are growing vegetables in containers, please give them a try. You'll be happy with them!
Also, there are new and very complete directions on the web for making SWCs from 30-gallon tubs (which are larger - and more expensive - than the ones we made: ours are from 18-gallon tubs). These directions seem a bit unnecessarily fussy to me, but there's a video and a complete guide. They are intended for TWO tomato plants.
The directions include self-supporting cages. But you know, those are the useless kind of cages. I don't believe they would support a large tomato plant adequately. We use circles of remesh - the heavy wire mesh used to reinforce concrete construction. These are MUCH stronger than the cages shown in this set of directions.
The directions and video are here: http://www.tomatofest.com/tomato-earthtainer.html
Incidentally, Tomato Fest has an excellent, huge selection of heirloom tomato seeds for sale.