With the growing awareness of the danger of chemicals like phthalates and BPA leaching from plastics, you’ve probably checked that the plastics you use when you cook, take a drink or store leftovers are safe. But have you thought about the plastic pots and containers you use in your garden?
As a kid, I grew up running through the farm fields that were my backyard, playing hide and seek in the cornfields and hurtling the wide strips of black plastic that farmers use to help warm the soil and control weeds around plants like strawberries. Now, I live on a wooded lot where a plethora of tough tree roots make gardening in raised beds and containers almost a necessity. Since our lot is shady, we often use black plastic storage boxes as containers. They work well. But are they safe?
Get plastic’s number
Not all plastics are the same. According to the Environmental Protection Agency, the easiest way to tell which kind of plastic you’re dealing with is to look for the resin identification code, a number between one and seven that is usually on the bottom. It’s often inside a triangular recycling symbol. Each number corresponds to a type of plastic.
1 is PET or polyethylene terephthalate
2 is HDPE or high-density polyethylene
3 is Vinyl or poly vinyl chloride
4 is LDPE or low-density polyethylene
5 is PP or polypropylene
6 is PS or polystyrene
7 is other or mixed plastics
Plant by the numbers
Some gardeners choose to avoid plastic containers totally. Others use any handy container; they are unconcerned about leaching because scientists claim that the BPA molecule is too large to be easily absorbed by plant roots, as Gardening Know How explains.
For those in the middle who want to use plastic, but prefer to minimize the risk of nasty chemicals leaching into the soil they’re growing food in, most experts seem to agree that containers and pots marked with the numbers 2, 4 and 5 are generally okay. These are the same plastics considered safe for food storage.
Dodge the dangers
Cautious gardeners will avoid plastics with the numbers 3, 6 and 7. According to National Geographic’s Strange Days on Planet Earth, plastics marked with a 3 (vinyl) are linked to nasty chemicals like lead, DEHA, dioxins, ethylene dichloride and vinyl chloride. Plastics marked with a 6 (polystyrene) are known to leach styrene, a neurotoxin. Plastics marked 7 could be a mix of anything, so you can’t tell if they harbor dangerous chemicals or not. The Micro Gardener suggests that you might also want to consider what the container has previously stored before deciding whether or not to plant in it.
Plastics are widely used in agriculture, but I freely admit to being concerned about the possibility of dangerous chemicals leaching into my family’s food. Fortunately, the storage boxes that work so well for me are labeled with a 5, which is considered safe. For now, I intend to keep using them and other “food safe” plastics in the garden. But I’m definitely going to pay attention to what I’m using and avoid products made from plastics that have been associated with health risks.
Looking for more gardening? Check out “Plant These Five Flowers for a Better Vegetable Garden.”
“Choose Safe Containers for Growing Food” — The Micro Gardener
“Growing Plants In Plastic Containers: Can You Grow Plants in Plastic Pots Safely” — Gardening Know How
“Plastics” — EPA.gov
“Pots, Pans and Plastics: A Shopper’s Guide to Food Safety” — Web MD
“National Geographic’s Strange Days on Planet Earth” — PBS.org