Polyvinyl chloride is a commonly used but seldom recycled plastic (see Reference 1, page 2). Most household and infrastructural pipes are made from a PVC known for its rigidity, longevity and water tightness. These qualities contribute to the material's upcycling and reuse potentials, especially as indoor planters. Repurposing PVC pipes extends their life and reduces the amount of plastic in the waste stream; growing food reduces manufacturing- and transport-related environmental demands.
PVC pipes come in a variety of types, sizes and previous uses, so it is important to find the right source for reuse. The sizing and eventual form of the pipes should be selected based on the soil needs of the intended plants. Flexible PVC pipes and any PVC manufactured before 1977 should not be used due to risk of leeching plasticizer chemicals or vinyl chloride (see Reference 2 and Reference 3, page 4). It is prudent to confirm the original use of the pipe, because residues could be hazardous to plants. Pipes should be cleaned and sanitized before planting.
When designing an indoor planter from PVC pipes, the size, placement, stability and drainage needs of the intended vegetable plants are important concerns. Beginning seedlings require only a small amount of soil, but the demands of adult plant roots are greater. Different plants have specific light and drainage requirements that can guide the eventual placement and soil types for the planter. Vegetable plants that grow tall or climb, such as tomatoes or peas, may need to be staked as they grow. Root vegetables may be less conducive to PVC pipe planters due to the amount of soil needed and the access space required for harvest.
Smaller-diameter PVC pipes may be used to hold plant socks or cups within holes cut into the pipe, while larger pipes may be sawed lengthwise into sizable planting troughs. Large openings in a pipe allow more soil aeration for root health (see Reference 3, page 4). Long trough shapes may need to be sloped or perforated with small holes to improve drainage.
The chlorine content and a variety of chemical additives in PVC are understood to be hazardous to the environment in most disposal scenarios, and the material's effect on human health may not be fully understood. Government policies worldwide are aiming to reduce the production of new PVC and develop better methods for disposing or recycling it. PVC is widely found in water pipes and greenhouse farming applications, including planters, irrigation systems and protective films. (See Reference 3, page 4.) To date, no conclusive studies restrict the use of PVC, but many organic farmers and environmental activists stand against the use of plastics, especially of PVC. Other green activists support the repurposing of used PVC as an effective method for reducing the amount of the material entering landfills or being incinerated.
- U.S. Environmental Protection Agency: Documentation for Greenhouse Gas Emission and Energy Factors Used in the Waste Reduction Model (WARM): Plastics
- American Water Works Association: Widespread or Isolated? -- Old PVC Pipe a Potential Problem
- HortTechnology: Use of Plastics in Greenhouse Vegetable Production in the United States
- European Commission Green Paper: Environmental Issues of PVC