Are Plastic Containers Safe For Gardening? - Backyard Boss
We are reader supported. External links may earn us a commission.

Are Plastic Containers Safe For Gardening?

Gardening is a great way to reconnect with nature and grow your own food, but what happens when all you have are plastic containers? Growing your own food is the first step to becoming self-sufficient, but maybe you lack the space? Container gardening is a trendy alternative for many gardeners as they can grow various plants in lightweight plastic containers that are easy to move, maintain, and replace. But if you’re health-conscious, you may have wondered how growing plants in plastic containers affects your health.

So, are plastic containers safe for gardening? Should you be worried about the soil and your plants absorbing chemicals that leach out of plastic? Learn more about how plastic containers shape your gardening style below!

Understanding Plastic Containers for Gardening

View of an urban garden in plastic pots with chives and garlic in the foreground
Image credits: andres barrionuevo lopez via Shutterstock

Although plastic looks and feels the same, they come in different variations, classes, and types. For example, the plastic used to create a baby’s milk bottle isn’t the same as the one used to create a recyclable water bottle.

To help people understand the kind of plastic they’re using, The Society of the Plastic Industry, Inc (SPI) introduced Resin Identification Code (RIC) in 1988. This helped people make conscious choices about the type of plastic they wanted to expose themselves to.

Today, ASTM International controls plastic resin number regulation.

So, What Do These Numbers Mean?

Variety of colorful ceramic and plastic flower pots on the shelf in a plant store. Shopping for trendy pot flowers and home interior design concept. Selective focus, copy space
Image credits: lermont51 via Shutterstock

If you turn a plastic container or bottle upside-down, you’ll see a three-arrow triangle with a number inside:

RIC Description Used In Impact on Gardening

1

Polyethylene Terephthalate (PET or PETE) Used to create plastic jars and containers for one-time use. It’s recyclable. Don’t grow anything inside this, as it can break down easily when exposed to light and heat. Use it as a temporary cloche for young plants.

2

High-Density Polyethylene (HDPE) Used to create cloudy milk and detergent bottles. Extremely heat resistant and hard to break down. It’s recyclable. You can use this to carry liquid, i.e., water, fertilizer, feed, etc. You can even use it to DIY scarecrows to keep birds away.

3

Polyvinyl Chloride (PVC) Used to create pipes, wheelbarrows, and large detergent containers. Has recycling limits. Not safe for gardening as constant exposure to heat causes chemical leach.

4

Low-Density Polyethylene (LDPE) Used to create trash bag liners, food containers, shrink wraps, and squeeze bottles. Generally not recyclable. In your garden, you can use this type of plastic to store soil or cover your hoop house.

5

Polypropylene (PP) Used to create straws, bottle caps, and microwavable containers. Is recyclable unless black. You can use this plastic for flower pots, plant trays, ropes, and netting. This is because it has good resistance to wear and tear.

6

Polystyrene (PS) Used to make packing peanuts, Styrofoam items, and takeaway containers. Not recyclable. Don’t use styrene because the International Agency for Research on Cancer (IARC) classifies it as a possible human carcinogen.

7

Catch-all. Includes acrylic, nylon, polycarbonate containing BPA, and polylactic acid. Used to create sunglasses, goggles, mobile phones, and CDs. Don’t use this plastic in your garden because it could contain BPA that’s harmful to health.

Hopefully this list proves helpful when you’re looking for a new planter. There are some plastics that are just unfit for planting. Chemical leaching is something that all gardeners should be aware of.

Using Plastic in Your Garden Safely

plastic resin identification
Image credits: Trounce via Creative Commons

Each RIC is made from different kinds of plastic with unique properties that leach chemicals. And you guessed it, they break down differently too. Understanding the type of plastic you’re dealing with in your garden is essential to see how it affects your personal health.

Don’t use any plastic with RIC 3, 6, and 7, as they’re unsafe and could leach harmful chemicals into the soil when you constantly expose them to heat and light.

Most gardeners agree that wood, metal, bricks, and stone are the best planter materials. But if you can’t use these materials and prefer plastic, use RIC 5 to grow edible crops and RIC 1, 2, 4, and 5 to grow other non-edible plants.

You can safely use plastic in your garden, but you’ll need to monitor the type of plastic you use to grow your plants. Have fun but be cautious!

Tips for Growing Plants in Plastic Containers

Adding soil in pot
Image credits: Karolina Grabowska via Pexels

Apart from knowing what type of plastic you’re using, it’s important to learn how to use it correctly. Using safe plastic correctly helps prolong its life, prevents material compromise, and limits or prevents chemical leach. This will be financially beneficial in the long run because you won’t need to replace your pots or bags frequently.

1. Don’t expose your plastic pots to extreme heat

When it’s too hot outside, it’ll be too hot for the plants growing in your pots, even if they’re sun-loving. If your pots are on the balcony, invest in high-quality water and weatherproof curtains, like Bonzer’s Sheer Outdoor Curtains, to shield them from prolonged exposure to direct sunlight. If your plastic pots are exposed to direct sunlight daily, they’ll degrade quickly, chip, and break sooner than expected.

2. Don’t buy black or dark-colored pots

Placing black pots under direct sunlight is a recipe for heat! This is because dark colors absorb sunlight and convert it into heat. Although black pots won’t bake your plants, if you keep them under direct sunlight, the soil’s moisture will evaporate faster, leaving it dry. From the pot’s perspective, this could lead to breakage. If you have no choice but to buy dark-colored pots, invest in some sort of shade to prevent prolonged exposure to direct sun.

3. Use potting soils with high organic matter

According to research, soils with high organic content degrade pesticides and prevent them from leaching into groundwater. This is because pesticides automatically attach to organic matter. When you add organic matter to your soil, you usually mix it in the soil’s top three to five inches.

Going by the research, the more organic matter your soil has, the higher the chances that the pesticides are ‘being held’ at the top few inches of the soil. Thus, potting soil with high organic content in plastic containers can help catch BPA and other leached chemicals (if any) and prevent them from reaching the roots.

Lettuce Romaine Calm!

Plastic containers, even those deemed safe for gardening, may release small amounts of chemicals into the soil—however, safe plastics leach low amounts of chemicals into the soil.

Use RIC 5 to grow edible crops, and avoid using RIC 3, 6, and 7 for gardening purposes because they can leach dangerous chemicals into the soil, causing various health problems. Contact your local authorities to find out how to safely dispose of unusable plastic.

As always, leave your experiences, thoughts, and questions in the comment section! And share with friends and family who might find this helpful.

Happy Gardening!

shares