If you’re thinking of building or buying new raised garden beds, you may be wondering what the best materials to use are. One material that you might be considering is aluminum, but is it safe for raised garden beds?
Aluminum isn’t safe for raised garden beds because high levels of it can be damaging to plants and humans. Although aluminum raised beds won’t always cause health issues, there is a high probability they will. For that reason, it’s best to use raised beds made of other materials, like steel or wood.
The rest of this article will discuss the safety of using aluminum for raised garden beds in greater detail. It will also discuss other kinds of metal raised beds and whether aluminum is carcinogenic or not.
Why Isn’t Aluminum Safe for Raised Garden Beds?
Aluminum isn’t safe for raised garden beds because it has the potential to seep into the soil and crops, causing death and other issues in plants. Although this only occurs if there are high amounts of aluminum present, there is always a risk that aluminum toxicity may occur.
Aluminum toxicity is also known to cause problems in acid soils. This means that plants growing in acid soils are more likely to experience growth issues if exposed to aluminum (for example, in the form of a raised garden bed).
However, it’s also important to note that aluminum is considered safe when used as a food or medicinal additive, so it’s certainly not the most harmful material you could use.
But it is possible for a raised garden bed made of aluminum to contaminate soil, especially if the soil remains there for a long time. With constant exposure, the soil has a higher risk to experience problems. The same goes for plants that are in an aluminum container for long periods.
Is Aluminum Always Toxic to Plants and Soil?
Aluminum isn’t always toxic to plants and soil. It’s generally only harmful if there is a high enough amount present. In fact, small amounts of aluminum are good for plants and soil. But since aluminum occurs naturally in the soil, there is no need to add extra.
However, according to Western Australia’s Department of Primary Industries and Regional Development, aluminum can become toxic when the soil’s pH level decreases. When this occurs, plants can suffer aluminum toxicity.
A big issue with aluminum toxicity is root health. When a plant gets too much exposure to aluminum, the roots may become weak and brittle. Additionally, the plant will grow more slowly (or stop growing entirely).
Plants that are at high risk for aluminum toxicity are those that prefer acidic soil, such as blueberries and hydrangeas.
So by adding an aluminum container to the soil, you’re increasing the risk of aluminum toxicity. The best way to prevent this is by avoiding aluminum containers.
But it’s important to note that aluminum raised beds aren’t always going to affect your plant or soil’s health.
For example, if the soil in question has a high pH level, the soil and plants are less likely to experience aluminum toxicity. This is because the higher the pH, the less soluble aluminum becomes.
Symptoms of Aluminum Toxicity in Plants
If you are currently using an aluminum container for your plants and have noticed they’re starting to look less than ideal, you might be wondering if it’s because of aluminum toxicity. There are specific symptoms you should look out for, and they include the following:
- Slow or stunted growth
- Oddly dark leaves
- Wilting leaves
Although these symptoms may indicate aluminum toxicity, they may also indicate other problems, such as over or under-watering. Therefore, you shouldn’t assume that your aluminum containers are the issue right away.
Another indication of aluminum toxicity is brittle and weak roots. Of course, you’ll only know if the roots are brittle by removing the plant from the soil, and you may not want to do this right away. But if you have no other option, it’s good to remove the plant from the soil and examine the roots.
Is Aluminum Carcinogenic?
Aluminum is not considered carcinogenic. However, there haven’t been many studies done on the topic. Only very high exposure to aluminum can cause health issues, but these issues generally don’t include cancer.
According to a study by the National Library of Medicine, people are more likely to get cancer from aluminum exposure through aluminum production. So if you use an aluminum container for gardening, you don’t have to worry about getting cancer.
Nonetheless, you may want to avoid using aluminum for your raised garden beds containing edible plants.
To avoid potential problems for your plants or your health, you should consider using a different material for a raised garden bed.
Aluminum vs. Other Materials for Raised Garden Beds
Aluminum is only one kind of metal. There are many other metals out there, and not all of them are as toxic to soil and plants. One of the most significant benefits of using a safe metal container to grow plants is that metal lasts much longer than wood because it doesn’t rot or get moldy.
There are also non-metal materials that are safe for raised garden beds.
Below are some of the safest metal and non-metal materials that you can use for raised garden beds.
Steel
Many raised garden beds are made of galvanized steel, which means there is a layer of zinc on them to prevent rusting. Because of this, most steel garden beds are highly durable and long-lasting. And although high amounts of zinc can damage plants and soil, most galvanized steel only has small amounts of zinc. This means they’re perfectly safe to use!
Plastic
You may also want to consider a raised garden bed made of hard plastic. It’s no secret that plastic contains some chemicals and isn’t the best for the environment. Still, raised garden beds made of plastic are safer than aluminum and usually fully recyclable.
Additionally, they tend to last longer than wooden raised beds because they’re less susceptible to rotting.
In addition to plastic raised garden beds, you can also purchase plastic pots. These are useful if you’re tight on space but want to grow a small number of plants or vegetables.
Wood
Possibly the most popular material for a raised garden bed is wood. The most common types of wood used are cedar and cypress. Cedar is so popular as a raised garden bed material because it has a natural resistance to rot and other annoying issues.
Preventing rot is highly important for garden bed material because the soil is always moist. This creates an environment for bacteria and fungi to grow, causing problems for the wood material.
Cypress is another type of wood with a natural resistance to rot, so it’s another popular option for gardeners and homesteaders.
Other woods can also be used, but it’s essential to seal them with an appropriate sealer if you want them to last as long as possible. Some examples of plant-safe wood finishes include:
- Shellac
- Flaxseed oil
- Lacquer
What Is the Best Material for a Raised Garden Bed?
The best material for a raised garden bed is cedarwood because it is safe and lasts a long time. Any untreated wood is a good option for a raised garden bed because it won’t release any harmful chemicals into the soil.
If you want to use untreated wood, you can treat it organically using a non-toxic material like flaxseed oil. This essentially helps it last longer because untreated wood will break down quicker than treated wood. But of course, treating the wood isn’t necessary.
And if you’re still wondering if aluminum is a good material for a raised bed, the answer is no. But as mentioned earlier, you can opt for galvanized steel instead if you want to use a metal container. It’s safer than aluminum, and many steel containers are available to buy across the country.
You should also avoid using tires as raised beds because, like aluminum, they can also emit harmful chemicals into the soil, plants, and air. To learn more about the dangers of using tires for gardening, you can check out my other article: Is It Safe to Grow Vegetables in Old Tires?
Other materials that I haven’t mentioned yet are concrete and stone. These are other excellent options if you’re looking for something sturdy and non-toxic!
Conclusion
Aluminum is generally not safe for raised garden beds because it can seep into the soil and surrounding plants. Therefore, it’s best to use a different material like wood, steel, or concrete.
Although small amounts of aluminum are safe for soil and plants, high amounts can cause severe problems (and even plant death). If you’re looking for something like aluminum that’s also safe, you should consider a galvanized steel raised bed.
Some people use aluminum containers for plants and experience no issues. However, it’s best to stay on the safe side and use other, safer materials.
