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Is it Safe to Use Galvanized Metal for Raised Beds?

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Many gardeners are beginning to construct raised garden beds for various reasons. Raised beds can be constructed with many different materials, the most popular being wood and rocks. Recently, people are using galvanized metals to construct raised beds. But is galvanized metal safe and recommended in the construction of raised beds?

Raised-bed gardening

Galvanized metal is perfectly safe to use in constructing your raised bed. It is strong and built to last a long time. Galvanized metal also does not have negative effects on your plants. It is completely safe to plant in raised beds made of galvanized metal.

Making Raised Garden Beds Using Galvanized Metal

There are many questions to answer about using galvanized metal if you have never worked with it before.

A raised bed vegetable garden with wax beans, lemon balm, mint, red leaf lettuce and tomatoes in a backyard garden

What is Galvanized Metal?

You know how most metals begin to rust after a few months in the elements? Well, metals such as aluminum and zinc do not get rusted. Galvanization is the process of coating metals that easily get rusty using metals that do not get rusty. People mostly use zinc in galvanization.

Advantages of Using Galvanized Metals

Some advantages of using galvanized metals are:

  • Long Life: The most prevalent form of metal damage is rust. Galvanized metals do not easily rust, so they have a long life. Most galvanized metals can endure for 50 years or more.
  • Reliability: When using galvanized metals as a frame for your raised bed, you can be certain that your raised garden bed will not fall or collapse one day.
  • A Form of Season Extending: Being made of metal, galvanized metal raised beds can conduct heat, so they can store the heat of the sun and heat the soil close to the edge of the raised bed. This heat can extend the growing season to accommodate heat-loving plants in late autumn.

Is it Safe to Use Galvanized Metal to Make Raised Beds?

Using galvanized metals for raised beds is fully safe. Consider the fact that most water supply pipes are made with galvanized metal. This should show you just how safe galvanized metal is for use in your raised beds.

galvanized steel

Zinc in itself is a plant micronutrient. Even though plants do not need zinc in large quantities, they need zinc to make the process of photosynthesis more efficient. Other micronutrients that plants need are:

  • Iron (Fe)
  • Boron (B)
  • Copper (Cu)
  • Chlorine (Cl)
  • Manganese (mn)
  • Molybdenum (Mo)

Is it Safe to Consume Products of Plants Grown in Raised Beds Made of Galvanized Metals? As you already know, galvanized metals do not harm plants and if any zinc leaches from the frame, it will be beneficial to the plants.

Note that plants only consume zinc and other micronutrients in very little quantity. Also, note that just like plants, we need zinc in little quantity, but high exposure is toxic to us and plants.

Caring for Raised Beds Made of Galvanized Metal

Galvanized metal is strong and durable, so a raised garden bed made of galvanized metals is not very difficult to take care of. There are, however, some ways that you can damage the raised bed frame.

Galvanized  Raised garden  Bed

Some ways to easily damage raised garden beds are:

  • Presence of Sodium Chloride (Salt): Salt causes metals to rust quickly
  • Acidity: Simply put, metals rust faster when exposed to acidic conditions
  • High Humidity: If the humidity level is above 60%, galvanized metals can corrode quickly
  • Presence of Moss and Lichens: Moss and Lichens, though they do not directly affect galvanized metals, can retain and build up moisture
  • Constantly Wet: Even though zinc does not rust, a raised bed frame that is constantly moist corrodes quickly.

Now that you know what makes galvanized metals rust quickly, how can you care for your raised garden bed to prevent the frame from getting damaged? Here are a few suggestions:

Watering Plants

When watering, you should not overwater your plants. Overwatering does not only damage the root of your plants and make them sick, it can damage the raised garden bed frame. Overwatering can cause soil moisture to build up and damage the frame.

Overwatering can also encourage the growth of algae and lichens.

Applying Manure and Compost

You should not use unfinished compost and fresh manure. By unfinished compost, I mean any organic (biodegradable) material that has not fully decomposed. Fresh manure needs extra time to decompose.

If you use these products, they can increase the acidity of the soil while they decompose. Remember that galvanized metals should not be exposed to acidity.

Shading Galvanized Metals

metal raised bed

If you do not like the heat of galvanized metals, you should consider constructing the raised bed at a shady spot.

Another way to prevent sunlight from reaching the raised bed frame is by planting crops that crawl such as cucumbers, indeterminate tomatoes, and watermelons.

Lining Galvanized Metals

What does it mean to line a raised bed made of galvanized metal? Lining means to coat the internal side of the garden frame with materials that serve different purposes.

For example, people use plastics to line their raised beds to prevent moisture from reaching the frame. Others line below the soil in their raised bed with weed fabric to prevent weeds from growing.

Some common types of liners for raised beds are:

  • Plastics
  • Cardboard
  • Weed Fabric
  • Underground Layer of Leaves

Why should you line your raised bed made of galvanized metal?

If you are growing water or acid-loving plants, you should consider lining the raised bed to prevent it from damaging quickly. Liners can increase the life of raised beds made with galvanized metals.

Other Materials Used to Make Raised Garden Beds

If you are not comfortable with constructing your raised bed using galvanized metal, you have many other options to choose from. Some great materials to use for your garden bed are:

flowerbed with concrete material
  • Rock
  • Cedar
  • Plastic
  • Redwood
  • Concrete or Cement

Some materials that you should avoid when constructing your raised bed are:

  • Tires
  • Railroad ties
  • Untreated pellets
  • Any material coated with toxic chemicals

You should avoid the materials above because they either contain a high amount of heavy metals or they contain chemicals that can kill plants and animals, therefore making the plant product unsafe for you.

Final Thoughts

Galvanized metals are fully safe to use as a frame for your raised garden beds. The zinc used to coat the metals does not corrode easily, but if it does, it can be consumed by plants (in little quantity).

After reading this article, will you use galvanized metals as their raised bed frame? What other materials are you considering? Share your thoughts in the comments section below.


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