Spurtopia's latest inventions - Double and Triple decker self-watering planter boxes

We recently shared our invention - Self-watering planter box (a "single decker" - one box) made from a styrofoam box and a piece of PVC pipe. Now we have come up with version two "double decker" (two boxes) and version three "triple decker" (three boxes).  The principle of a self-watering planter box is soil in the pipes acts as a wick bringing moisture up by capillary action, keeping soil in the box above the water storage, moist.

- The double decker comprises of two boxes, bottom box for water storage and top box for soil. It is made with three PVC pipes of about 100mm diameter and box height in length. A watering pipe in a corner of the box runs from the bottom and is the height of two boxes. In this pipe is a float with  a wooden skewer (a couple of skewers taped together to reach the top of the pipe), indicating water levels. The second box has small holes in its floor, punched with a screwdriver,  for better drainage and aeration of soil.
- The triple decker is an extension of a double decker with a third top box which has the bottom  cut off. It comprises of water storage in the bottom box, two boxes of soil and three PVC pipes.

Double Decker - Self-watering planter box

Triple Decker - Self-watering planter box

Advantages:
- The boxes when filled with home made organic soil and water are very stable (soil weight will push one onto other).
- Soil never gets waterlogged as excess water will overflow between boxes (no overflow hole required).
- Nutrition does not leach out - during heavy rain, nutrition is retained in the water storage and later plants will "suck" it up.
- Styrofoam as insulation, offsets external temperature and sun radiation fluctuations keeping soil at a steady warm temperature.
- Mosquito proof - only access to water is through watering pipe which is blocked by a float.
- Water efficient - only water used, is by plants.
- Huge water storage capacity - up to 40 litres in the bottom box so no need for watering for several weeks
- Made from free, readily available, recycled materials - styrofoam boxes sourced from a local fruit and vegie shop or fish market, old PVC pipe from kerbside collection or off-cuts from a plumber.
- Diverting material (boxes, pipes) from landfill
- Portable - moving boxes during seasons (position in part shade during summer and move to full sun in winter). If moving home, an established garden in styrofoam boxes comes along with you and provides you with already growing vegies.
- Raised garden - Boxes can be place on existing ground where nothing would grow due to poor soil quality or  tree roots sucking all the moisture and nutrition.
- Soil in a box is aerated from the bottom through small holes which provide plenty of oxygen for plants.
- Boxes are lightweight compared to boxes with gravel based water storage which also significantly reduces water holding capacity (gravel takes up space).
- Suitable for growing all kind of vegetables including root vegetables as well as small fruit trees.

Potential challenges:
- Styrofoam is plastic and might leach out chemicals - the box can be painted internally with bees wax to created a protective coat.
- Boxes might leak - a black construction foil can be used as an inner liner
- Sunshine might deteriorate styrofoam after a few years - an external coat of paint will stop styrofoam deterioration and create colourful, aesthetically pleasing boxes.

Double decker

 

Boxes  are water efficient  and store large amounts of water - up to 40 litres -  so they do not need to be watered for several weeks and you can go on a holiday for a month and the plants will have plenty of water to drink. Our boxes are over a year old and still in perfect condition even without paint.
When filling up boxes with organic soil, make sure you fill up wicking pipes properly so wicking is effective. When planting plants, water them for a couple of weeks from the top so they can establish their root system. Also soil will become more compact and wicking more effective.
In one of our single decker boxes, a self-seeded paw paw started to grow half a year ago. Now it is nearly two metres long. So it is possible to grow anything.

The double decker  is great for plants with larger root systems and higher water requirements such as tomatoes and cucumbers as they love lots of water. We harvested 5 cucumbers, over half a metre long off one plant). Also root vegetables such as carrots or daikon radish will grow there - if you plant them straight above a wicking pipe, you can harvest over half metre long, straight carrots.

Triple decker boxes with huge soil volume and depth (over 60 cm + 30 cm wicking pipe) can be used for any kind of root vegetables no matter where planted in a box. Huge soil volume  in the two boxes is sufficient even for a dwarf tree.

Plants growing in a double decker

In these three types (single, double and triple decker) self-watering planter boxes, any vegetable can be grown. 
We are fully aware that styrofoam is plastic and it most likely leaches out some substances. So far we have not found any evidence against growing vegetables in styrofoam boxes. People growing vegies in plastic pots or eating broccoli which was delivered in these boxes (in direct contact with Styrofoam) don't even think about that. This is a paradox. We believe that home grown vegetables in these boxes are a thousand times better than vegies from shop shelves.
In the self-watering planter boxes, we grow successfully all kinds of fresh tasty and healthy vegetables so we would like to share our invention with you. If we can make it for free you can make it for free.