Horticulture and Small Farms Extension Agent II
FAMU/CESTA Gadsden County Extension
While surfing the internet, perhaps you have read about and seen images of homemade “self-watering containers”. For the most part, these are devices with a built-in water reservoir. It utilizes wicking to move water against gravity from the reservoir to the container soil environment, a phenomena known as capillary action. Soil pore space provides the means for movement, in this case, rise of water. Self-watering containers are great for the busy or forgetful gardeners. They can also help you manage your water usage, garden indoors during winter and reduce the number of times one has to bend down to water ground level plants. An extension client provided me with all of the pre-cut materials to build a self-watering container system. We have put it together and are growing sweet potato vines in one, lettuce in another and a mix of ornamentals in a 3rd container.
Self-watering container illustrations: basic components needed (top), view of screen/divider assemblage and soil compartment (center), and finished containers with sweet potato vines, lettuce, and a mix of ornamentals (below). Photo Credits: Alex Bolques, Gadsden County Extension
The main component of the system is a plastic storage tub with a lid (see top illustration). Alterations to the lid were made to create a container rim with the remaining interior-lid material used as a screen to divide the soil compartment from the water reservoir below. The screen/divider, also known as an aeration screen, is supported by 4-4” perforated PVC under-drain pipe pieces that were ~6” long. Two of the 4” under-drain pipe openings were left exposed to enhance wicking. The screen/divider was also constructed with a 1” opening to accommodate a 1x18” PVC pipe. This pipe serves as a vertical reservoir fill tube.
To finalize the screen/divider assembly, it was fitted with a layer of landscape weed barrier fabric. The fabric has micro-pores, which also allows water to move through it. Openings were cut over the wicking tubes to allow water-to-soil contact. Lastly, two ½” holes were drilled on each side of the container opposite to one another and just above the screen/divider. A ½” PVC pipe was inserted into each ½” opening, from end-to-end. The pipe should be as long as the width of the container allowing for 1” on each end to fit a PVC end-cap (see center illustration). The ½” pipes with end-caps are used to prevent the container walls from expanding against the weight of the container soil, thus giving the container walls more rigidity. Potting media was added right up to the brim of the container, a layer of landscape weed barrier fabric was placed over the soil surface and secured with the lid-rim, holes were cut in the fabric for planting (x marks the spot), plants were installed and the water reservoir was filled using the fill-tube opening (a ½” hole should be made just below the screen/divider to prevent overfilling of reservoir), and you are done!
The materials needed to create your own self watering container can be found in most home improvement stores. Detailed instructions for this and other similar systems can be found by visiting http://www.postoilsolutions.org/documents/Earthbox.pdf.