Are cinder blocks safe for gardening?

QUESTION: Are cinder blocks safe for gardening? I’ve heard they can be bad for you and you aren’t supposed to use them, but I see raised bed gardens made of them all the time. Is it not a big deal? – Jackie K

GARDENING CHANNEL REPLIES: The short answer to this question is, it depends. The idea of a cinder block has changed drastically over the decades.

Cinder blocks were originally created from a byproduct created by coal fired factories in the early 1900s. However, the true cinder blocks stopped being manufactured in 1947.

The likelihood of you having antique cinder blocks hanging around are very slim. On the off chance, you are someone who found a great find and thought, “I wonder if I can use these for my garden?”

No, please don’t use antique cinder blocks for your garden. They aren’t safe as there’s a risk of materials leaching into the soil.

Yet, most of us have seen cute ideas for raised garden beds and other fun DIY projects that thrifty people have figured out how to create out of what we still commonly call cinder blocks.

These creations are usually made from blocks purchased at big box stores. Though they’re still referred to as “cinder blocks,” they aren’t. These blocks are made from concrete.

Concrete is made from sand, stone, and sometimes small amounts of fly ash. This is concerning to some people because there is no ingredient label on these blocks, so you can never be certain as to how much fly ash is in the material.

If you find this concerning, there are methods for sealing concrete blocks to avoid the materials from making their way into your garden plot.

However, if you aren’t too concerned about how much fly ash is in the concrete block, it could be one of the easiest methods for building a raised garden bed.

Ultimately, what materials you decide to use in your garden is a personal decision. Hopefully this information has given you some things to consider.

Now, take this information and use it to equip yourself in deciding what materials you do (or do not) want in your growing space and enjoy creating a garden you can be proud of.