Are Your Planting Containers Toxic?

Do you plant vegetables or herbs in containers? Some planting containers may be leaching toxins into your food….

If you’re a container gardener, an indoor gardener, or even if you just plant a few herbs in containers over the winter, beware of the pots you use, as some planting containers could leach toxins into the soil, which could be ingested by your plants, and then by your family!

Depending on what your planting containers are made of, they may contain chemicals which can be absorbed into the soil. Here is what to look out for, to make sure your indoor container-grown plants are safe for you and your family to eat.

Lightweight, and nearly indestructible, plastics have been the magic answer to a myriad of storage, transportation, and packaging dilemmas…. But many plastics— particularly when they’re exposed to sunlight, water, and high temperatures—leach toxic chemicals like bisphenol A (or BPA), vinyl chloride, or phthalates which are hazardous to human health…. Check the underside of containers to determine their suitability: numbers 1, 2, 4, and 5 are a good choice for planting edibles. Others are not.

Possibly the classiest choice for a planter, ceramic is practical as well. It’s durable, breathable, and generally made from natural ingredients (mostly clay). Ceramic has its own suite of challenges for the container gardener, but transferring harmful substances is, thankfully, not one of them—unless you opt for glazed ceramics….

An untreated wooden box is an excellent container for edibles except for the fact that, given time, it will rot. Slap on some stain or preservative paint, and things start to get complicated. Many wooden containers sold to gardeners are pressure treated to increase their lifespan and ability to stand up to moisture. The chemicals forced into wood during the pressure treating process (copper, chromium, and arsenic) arrest decay and generally don’t leach into soils much after the first initial rain. Arsenic isn’t something you want to build up in your garden soil, however. To minimize any chemical movement, scrub or power wash wood prior to usage…. To go completely au naturel, use wood that is rot resistant and requires no treatment at all: Cedar is the perfect pick.

Old tires have become a popular, salvageable item for growing root vegetables like potatoes and carrots. They stack easily, are free, and help warm the soil in the chilly months of spring. However, as tires age they release a litany of toxic compounds into the ground—including carcinogenic hydrocarbons….

A safe pick is metal. It’s true that in humid, moist climes, pots can quickly rust, but the oxidized metal doesn’t leach into the soil the same way lead does. If using a galvanized metal container (such as an old wash tub, trash can, tool box, etc) be careful: zinc (an essential nutrient) and cadium (a toxic heavy metal) can leach into the soil when it’s exposed to the right acidic conditions….

Foam trays can be recycled from fishmongers and grocery stores and are a great way to start seedlings.

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Rose S.

An avid gardener since childhood, I love sharing my passion for gardening with others! I have gardened in a number of different climates and settings, from large fenced garden plots, to tiny patio and container gardens, and I firmly believe that everyone can learn to grow at least some of their own food - no matter where you live. Growing your own food can help you take control of your own health and food supply, and there has never been a better time to get started!

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