Here is a list of materials for DIY sub-irrigated planter (SIP) for lettuce, green onions and garlic, and many other vegetables:
- a bucket or plastic storage box. Use BPA-free plastic. For example, Dollar Tree offers large "Sure Fresh" plastic containers for $1. There are 9-qt (2.2-gallon) plastic buckets at Dollar Tree that can be used as planters.
- water/air reservoir. Many plastic containers, for example, a plastic bowl for takeout food can be used for this. Drill multiple holes. Alternatively, the holes can be poked with a knife.
- draining tube. The same tube can be used to pour the water in the reservoir. You may need a funnel. A food example is 1/2-Inch Diameter Vinyl Tubing that is available for 27 cents per foot at Lowe's. Amazon offers a similar product: Watts SVIG20 Pre-Cut 1/2-Inch Diameter by 3/8-Inch Clear Vinyl Tubing, 20-Foot Length.
Significant benefits of SIP gardens over traditional "drench and drain" gardens include:
- Water savings in the range of 70-80%
- No runoff of water and nutrients
- Increased productivity of edible plants
- Sustainability - no more short life plants due to uneven watering
This bubble SIP design is an insert for any watertight container. The reservoirs are made from a wide variety of recycled food containers. Most of the bubble reservoirs can be made from round 48 oz Glad type food containers. The fill tubes are recycled water bottles. Cut the bottoms off and they sleeve together to make fill tubes for containers of varying depths. The overflow drain valves are made from readily available vinyl tubing.
The tools are simple but caution is advised when using a wood burning pen or box cutter. The wood-burning pen works well in making both the small holes (approx 1/8”) and the hole for the overflow drain valve. Push the pen tip through to the heated barrel and it will make a ½” hole for the tubing.
All of the plastic and resin planters (without drain holes) shown at the URL link below are widely available at modest prices from stores like Home Depot, Lowe’s, Walmart, Dollar Tree. They are readily adaptable to sub-irrigation using the “bubble SIP” design. The bubble metaphor reflects on the need for an online supply of both water and oxygen…just like a bubble.
Plants benefit by the fact that their root system resides right over an immediate supply of water and oxygen with no need for an electric pump. The principle of ebb and flow is modeled after systems used in modern greenhouse production. As the water rises by capillary action and used by the plant, additional air flows into the reservoir. There is always a balance of both water and air in the reservoir. Sub-irrigation like this is, in fact, a simple form of hydroponics.
Inside Urban Green: A Sub-irrigated "Bubble SIP" Water Conservation Test Garden http://bit.ly/1DuuvBL