The key element is the use of 4" diameter perforated corrugated drain pipe to form the water reservoir and air chamber. These beta test planters have already proven that the system functions like other sub-irrigated planters (SIPs). The forecast is that they will be highly productive and far exceed that of top-watered beds.
There is no need for any type of separator platform or soil wicking chambers (pond baskets, plastic food containers, etc.) as is typical with SIPs like the EarthBox and other do-it-yourself versions made from plastic tote boxes.
Note: It is important that the bottom of the raised bed be level. If not, there will be an uneven distribution of water through the planter.Salient facts:
- Date of Planting – May 25, 2010
- Location – Liberty Sunset Garden Center, Red Hook, Brooklyn, NY
- Plants – an assortment of edible plants
- Dimensions 48" x 48". Left planter – 11” high, Right planter 15” high.
- Reservoirs/Air Chambers
- Created from six sections of 4" diameter corrugated drain pipe. Wedging them from sidewall to sidewall eliminates the need to cap the ends of the pipes. Note: Unlike the photo, the pipes should be evenly spaced across the bottom of the planter. The spaces between the pipes form the soil wicks. It is the same as the method shown here and here using recycled plastics (i.e. milk bottles, nursery flats).
- The perforations in this type of drain pipe allow the water to flow from pipe to pipe without need for connecting pipes. They also allow air to oxygenate the soil.
- Sheet Plastic Liner – Due to a miscommunication, the sheet plastic liner in the beta test planters is only high enough to create the water tight reservoir (about 6”). Going forward, planters will be lined all the way to the top edge of the planter.
- Fill pipes – Recycled plastic water bottles eliminate the need for commercial piping (PVC, vinyl tubing, brass pipe, bamboo, etc).
- Overflow Drains - 1 1/4" vinyl tubing. Future planters will have a series of plugable 3/4" tubes aligned vertically to allow adjustment of the reservoir capacity.
- Sheet Plastic Mulch - This is an option. It prevents the growth of weeds and helps to conserve water by minimizing evaporation.