When people think about either adding to a garden, or for those who do not have a suitable area to plant a garden, many people consider using a container garden where you grow plants in smaller containers commonly made from plastic or fabric.
Plastic containers can be used for a container garden, but you need to make sure that the plastic is food-grade, meaning that it is safe to store food in and that chemicals in the plastic will not leach out into your soil and thereby enter your plants. You do not want to grow food thinking that it will be healthy for you and unknowingly have them contaminated with a cancer-causing chemical that leached into the soil from the plastic.
All plastic containers are required under federal law in the United States to be marked on the bottom of the container showing what it is made from and if it is a food-safe material or not. The marking will be the recycling triangle of arrows with a number in the center of it.
Check the recycling symbol on the bottom of the container. The quickest and most reliable way to check for food safety of a container is by checking the recycling number. This number will be between 1 and 7. As a good rule of thumb, the numbers that are safe to use with food are 1, 2, 4, and 5.
The best type of plastic for use in long-term food storage is high-density polyethylene (HDPE), which is indicated by the “2” symbol. HDPE is one of the most stable and inert forms of plastic, and all plastic buckets sold specifically for food storage will be made from this material
Other types of plastic acceptable for food storage include PETE, LDPE, and polypropylene (PP). These plastics are represented by the numbers 1, 4, and 5 respectively.
An exception to this rule is bio-plastics, which are categorized under the catch-all symbol “7.” Bio-plastics are plastic-like materials that are synthesized from plant-based sources such as corn. These materials are nonreactive and can be used to store food, but note that not all plastics marked as “7” are bio-plastics.
Personally, I will only use plastic containers that are marked with either a 2 or a 5 recycling symbol for container gardening . These containers work well as growing containers and hold up well outdoors for several years.