But container gardening has several drawbacks. Containers dry out quickly and if you forget to water, especially with vegetables, you can easily kill your plants. In fact inconsistent watering is probably the number one cause of container plant failure. Container gardening also uses a lot of water and can be messy, as the excess water flows out of the bottom of your pots leaving muddy stains on decks and balconies.
Thankfully, there is an elegant solution in the form of self watering containers. The principle is simple. Rather than having a hole in the bottom of the pot, there is instead a reservoir of water. Potting soil is suspended above the water reservoir by means of a perforated barrier. Circular “wicking chambers” reach down into the reservoir and draw water up to the plant’s roots. The reservoir is refilled by means of a pipe that comes out of the top of the pot and the soil in the pot is covered with a layer of plastic that acts as mulch. Depending on how deep the water reservoir is, it’s possible to go many days without having to add water. This arrangement, combined with the mulch layer on top prevent wasteful over-watering that can occur with conventional pots.
Best of all, while commercially made self watering containers such as the Earthbox® are available, it’s possible to build your own with these detailed instructions (warning–long pdf) by Josh Mandel. Or take a look at our how-to video:
We built our self watering container with an old plastic storage bin. The ubiquitous five gallon bucket also makes an excellent choice. Clever and water-wise folks may want to pimp out their self watering containers with overflow tubes to carry excess water out of the drainage hole and into a plastic milk bottle. Instructions for doing this can be found here (another pdf), and this might be wise for those considering placing these things on a roof.
Speaking of roofs, one drawback to self watering containers is that they are heavy once filled, so make sure that what you put them on can support the weight. Also, fill them with soil and water only after you have placed them where they need to go, since they can be a bitch to move once full.
Now, we don’t have much sympathy for the aesthetically minded, but some might consider a bunch of five gallon buckets or plastic tubs ugly. Personally we like the meth lab/cannabis farm chic this type of gardening suggests, but for the yuppies out there it’s also possible to put your home brew self watering container within a larger and more attractive pot if you’ve got the dough to blow. Fill the extra space between your self watering container and the pot it’s sitting in with gravel. Check out our instructions on how beautify your self watering container.
Now, apartment homesteaders, get out there and grow your own damn food!