The short answer is yes, they are absolutely safe for gardening. Since acidity is needed to break down the zinc coating that galvanized steel has, and most garden soils are neutral, it won't do much. In addition, zinc is an essential micronutrient for plants and a normal part of soil. We'll cover all of this in detail later!
We love metal loft beds so much that they were the first product we chose to start our online store. With a variety of options, we think you'll love these high quality galvanized garden beds.
Galvanizing is the process of bonding a layer of zinc to the surface of steel or other ferrous metals such as iron. This process prevents steel or iron from rusting when exposed to moisture.
Most galvanized steel is made by hot dipping process. The steel plates, whether corrugated or smooth, will be fully immersed in the molten zinc. This creates an even coating on the steel surface. The metal is sometimes cooled to allow the material to fully bond before being dipped back into the secondary coat.
Not all galvanized steel is coated with pure zinc. Some galvanized metals are alloyed heat treated. For example, Aluzinc is an aluminum and zinc coating commonly used in hot-dip galvanizing. Aluminum forms the outer layer, which protects the zinc and steel inner layers from moisture damage.
What is the galvanized steel sheet used for?
A better question is what galvanized steel is not used for. Galvanized steel is the material of choice for livestock troughs, barn and water storage container exteriors, shed structures, roofs, gutters and downspouts, and many other products. It is sometimes used as a durable fencing board.
Galvanized steel pipe has also been the standard for home plumbing for decades. Although galvanized pipes are no longer replaced by PVC and copper pipes, most older homes still use galvanized pipe fittings. As long as the zinc coating remains intact, these pipes will continue to serve for many years.
In food use, galvanized metal is less common in cooking and more common in storage containers. When zinc is heated to high temperatures, it emits gases into the food and the surrounding air. This makes it unwise to use in a cooker. However, containers made of galvanized steel are great for storage!
Will galvanized metal leach zinc?
Yes and no. If you have extremely acidic water, such as acidified water from a well that has not been treated to neutralize the pH, the zinc will gradually break down. This process can take decades if the coating is thick. Most municipal water sources neutralize the pH of the water through their facilities, which means it's less likely to be a major problem.
In fact, zinc is a normal component in most soils. Both plants and humans require small amounts of zinc to survive. You can also find it in your daily multivitamin! Plants need less zinc than we do, but it's still a necessity. The trace elements they might pick up from your bed won't harm any food you grow, nor the plants themselves.
Zinc itself may not pose a threat to human or plant health, but impurities in zinc may. Concerns have been raised about lead contamination in zinc. This has led manufacturers to take steps to reduce the risk of lead contamination by using only pure zinc or aluminum-zinc alloys. Lead in galvanized containers is less likely to be a problem than lead that occurs naturally in soil.
So yes, acidic conditions may cause some zinc to leach. But this will be minimal, and some plants may actually prefer trace amounts of zinc in the soil. As long as the steel is from a reliable manufacturer, there is no need to worry about your bed leaching toxins.
Will galvanized metal leach aluminum?
While it can never be said never, galvalume does not pose a significant risk of aluminum leaching into the environment. The aluminum used for galvalume, which is lighter than zinc when molten, floats to the outer surface during the hot-dip plating process, providing an ultra-thin protective layer for the zinc. This protective coating prevents leaching of the more soluble zinc, and it can even add another layer of protection to the aluminum surface if there are any additional coatings such as paint.
Aluminum itself is not as soluble as zinc, which is why it has long been used for food storage. Additionally, it is resistant to acidic conditions, an important consideration when paired with the more soluble zinc. If it weren't for the aluminum linings in canned food and aluminum beverage cans, we wouldn't have most of the long-term food storage options we currently have! There were concerns about the safety of aluminum cookware as far back as the 1960s and 70s, but after in-depth research it was determined that even this posed no risk to humans. Since your garden beds will never be exposed to the hundreds of degrees of heat your cooker generates, the very limited amount of aluminum in the galvanized coating is very safe to protect the zinc from degradation, even in direct sunlight.
Can galvanized steel sheets be used for raised beds?
Absolutely! Galvanized metal raised beds are becoming some of the most popular garden beds. They are durable, strong, damage resistant, will not rot like wood, and will last for decades. Plus, they look great and can evoke a ranch or industrial vibe. A galvanized planter won't expand or contract, doesn't need oiling or painting to maintain it (although if you want, you certainly can), and will accept whatever Mother Nature has in its way.
Shallow raised beds are easy to fill with your preferred pH-neutral, well-drained soil. However, deeper beds may require more packing material. We have a great article on how to fill tall metal garden beds that goes into depth on this topic!
Are Metal Raised Garden Beds Too Hot?
not at all! It's true that most metals heat up in sunlight. But moist soil is an amazing coolant for hot metal. Generally, your vegetable garden or pots won't get too hot, especially if you've been watering them.
Because metal can conduct some heat, the soil attached to the sides of a raised bed may be warmer than the center of the bed. This is actually a beneficial thing, especially in spring. The soil in raised beds heats up faster than the ground, allowing you to start a vegetable garden faster. Your seedlings will love the warm soil for their roots!
In mild climates, metal raised garden beds can help you maintain a more consistent soil temperature throughout the year, provide good excess moisture drainage, and more. Hard, sturdy material will provide a good cold frame base for your overwintering plants. These beds hold moisture well when using a soaker hose.
Raised garden bed options
Choosing a commercially manufactured galvanized garden bed can be complicated. There are a surprising number of options on the market, from large vegetable garden styles to basic planters.
I am very partial to the beds designed by the Australian manufacturer Birdies. These sturdy galvanized raised beds are extremely efficient. They are galvanized, a material composed of 55 percent aluminum and 43.4 percent zinc with a small amount of silicon. Each container is designed with practicality in mind. Some even come in multiple configurations, allowing you to choose the exact size and shape you need!
Those of us with limited planting space may be interested in their collection of galvanized planters and planters. The patio-balcony-deck line (CBD for short) is a great line. Instead of corrugated metal, they opt for a sleek, sleek and streamlined design that fits seamlessly on porches and patios.
But if you have a lot of space in your garden, fear not! Their original collection is perfect for you. Available in 15" and 30" depths. These beds are generous in size and can be configured to suit your space. I prefer their long and narrow configuration (about 5.25'x2'). But there are square or rectangular options for other widths as well. These are great for growing vegetables and you'll be using them for decades.
Do you have a place with only one round bed? The tall, circular bed provides the perfect habitat for your potato plants, while the depth allows you to continually add soil and expand your potato harvest. You can top it with concentric rings of lettuce for an eye-catching salad garden, or for an herb display. The options are endless!
DIY build:
If you have galvanized sheet available, you may want to consider DIY beds. Make sure you have good quality galvanized steel for roofing or other steel exposed to the elements. You'll also need wood corner posts to hold the steel, and some corner burrs to keep the edges from fraying.
There are many designs of these types of beds online, a quick search will find a list of patterns and materials that are available for you. There are over 50 more loft beds on our list! One thing I would recommend, however, is to reinforce the sides of the deeper beds with galvanized pipe. A short length of pipe is bumped into the soil outside the bed, preventing the steel from bending outward as it fills with soil.
One of the considerations with these DIY beds is that they do require wood and metal. Wood has a shorter lifespan than galvanized steel, so you may eventually need to replace the corner posts and any other wood used in your construction. You may be able to extend the life of your posts if you paint them with an exterior paint first, but be careful to choose a product that won't leach chemicals into the soil.
Also, steel plates may have sharp edges, so you need to guard against potential injury. It was necessary to make a roof to cover the exposed edges of the steel. You can create a bench-like surface by mounting a 6- or 8-inch-wide plank on top of the bed and screwing into the corner posts to secure it. This will also hide the open end of the stiffener tube.
Keeping Your Metal Loft Bed Safe
Galvanized steel is a strong material that can withstand most garden uses. But there are ways to make sure your containers are safe for decades to come!
Avoid using fresh chicken manure in the garden. Amazingly, its acidity breaks down the zinc surface faster, putting the steel at risk of rust. Instead, use composted chicken manure or other organic options.
Choose plants that will grow in neutral soil and keep the soil pH on the neutral side. At neutral levels, zinc is less likely to break down into the soil.
If you are growing acid-loving plants, consider using a liner. Heavy plastic keeps acidic soils from direct contact with metal. Just make sure the plastic only covers the sides for good drainage.
Modify heavy clay to loosen it. Raised beds need well-drained soil to ensure they don't turn into muddy ponds. Also, clay is a very fine particle that can cling to the sides of the bed, and caked layers of clay can damage zinc finishes more than sandy soils.
So what have we learned? Zinc coatings are safe enough for livestock feeding and drinking. It is less likely to leach into your food. Steel garden containers are less likely to get too hot for your plants. Best of all, you'll be able to grow healthy food in it. Commercial containers are available and are easy to assemble for quick installation. You can also do it yourself if you are familiar with the tools. There are also ways to extend the life of a bed that have been around for decades.
Not only is it safe to grow plants in galvanized steel beds, but you'll grow better food than what's on the market.
