Corrugated steel garden beds are getting quite popular these days, and for a good reason. The demand is there and steadily increasing, so manufacturers have stepped up and increased production where they can. The problem with some available types is that the top and bottom edges are left quite sharp. We now have the problem of making the edge safe without spending heaps. The solution is a simple one.
Can sharp edges on metal garden beds be made safe?
Split poly piping or similar pushed over the sharp edges can protect the gardener from potential injuries, making the edges safe for fingers and plant stems. The longer answer is below, with examples from our personal experience.
This article goes into the methods and the materials to consider. It is surprising how easy and cheap it can be.
When we redesigned our backyard to fit raised garden beds, the local hardware was out of the Birdies bed we needed.
There was an extended waiting list, so we contacted a local plumbing outfit that fitted sheet metal roofing in the construction industry. This plumbing business had recently started making garden beds with spare metal.
We bought several of these, but they all came with sharp, exposed edges. They were also no match for the quality of the Birdies garden beds we have since bought to add to the collection.
What are the risks of corrugated steel bed edges?
The primary risks from the edges of corrugated steel garden beds are cuts, abrasions, rust, and rusty steel-related injuries that can cause serious problems.
Another issue that can be of concern is harm to plants as they grow outside the boundaries of the garden bed. This tumbling over the edge can cut stems and other plant parts due to the overhanging weight resting on the sharp edge.
There are also a couple of danger issues and longevity questions with metal garden beds, and most revolve around the rusting of the walls over time. Rust can be an issue if the soil within the metal raised garden bed is too acidic.
Using soil like this is probably purely accidental and likely something that originated from the soil supplier, assuming the gardener bought the soil.
Rust can also occur in the metal where it has been drilled or cut with a grinder or snips.
The cutting of the sheets can be from cutting down an old water tank or similar as many people like to re-purpose items instead of taking them to the tip.
Cut-down water tanks have a serious safety issue if the cut is at the top of the bed and is left unprotected.
The edges of these beds are likely to rust at the cut, leading to potential nasty injuries to the gardener. At this stage, you may wonder if these metal raised garden beds are worth it, so “Why use corrugated steel raised garden beds?” might help.
We have also listed the disadvantages of these beds in “Organic raised bed gardening, what are the disadvantages?” for you to consider before lining up to buy them.
How to cover sharp edges with minimal cost.
Because the corrugated steel beds are thin sheet metal rolled into the corrugated form, the edge we need to cover is often under 1mm.
This thinness allows for fitting a garden hose or similar to the sheet edge if the hose is sliced lengthwise in a relatively straight line. This hose is then spread apart and pushed over the cut metal edge, protecting the gardener from potential rusty iron cuts and injuries.
Garden irrigation pipe, poly pipe to some, can also be used and is potentially better than nylon garden hose because of the UV stabilizing that is often incorporated into the material.
A material called Carbon Black is added during manufacture and will protect the pipe from UV for many years.
How long will edge protection last on a garden bed?
Longevity will depend on the edge covering tube you use. Nylon garden hoses of poor quality will not last as long as PE pipe.
Industry claims 50-80 years is how long UV stabilized PE pipe will last.
The only causes of your poly pipe deteriorating should be from strong acids and hydrocarbons like diesel and fuel oils. Otherwise, the tube will not rust, rot, or react with your garden bed sheet.
The best solution we have found using this pipe is the thin-walled low-pressure irrigation line 3/4 inch in diameter (19mm).
It cuts easily along its length and wraps around curved ends of raised garden beds with some persuasion. The pipe has enough spring to hold it on the garden bed edge without other fasteners. It can pop off if the sun is scorching and the plastic softens.
Suppose your raised metal garden bed has cut edges; it might be a good idea to paint these edges before fitting the pipe. This painting can help counter rust issues that remain hidden under the tube.
Why use corrugated raised garden beds
Raised garden beds are helpful for the following purposes.
- Gardening with raised garden beds can be easier on your back.
- Raised garden beds allow you to control the soil conditions and ground critters.
- The garden beds are light and self-supporting. Some beds require a belly bolt to keep the sides from bulging out.
- Some brands of raised beds have a range of colors that can look great. Shiny galvanized beds can be glary in bright sun. The shiny-sided beds may reflect heat in summer, though.
Gardening while standing is very appealing for anyone with a back issue or anything related to pain when bending over. So metal garden beds are the solution that many of us find.
The beds allow you to control the soil conditions to benefit the plants you wish to grow. Semi-permeable fabrics placed at the bottom of the bed as you fill the bed can aid in moisture retention. Metal mesh can stop burrowing critters from entering the bed from underground.
There are temperature issues near the metal sides of these beds in certain conditions, and we go into this in-depth in “Does the soil in metal raised garden beds get hot?” We recommend reading this one.
Alternative ways to protect sharp edges on raised metal garden beds.
Some people like the look of a timber top edge. They look great and can give the gardener a seat to rest on as they do their tasks.
The problem with wooden garden top edges is they are exposed to the elements and are wet when plants get watered.
Moisture will cause rot in the wood, leading to early construction work to replace the tops when they fail. This will happen eventually; it is only a matter of time.
Some raised garden beds have quite a bit of wood in their construction, and from our perspective, any wood that is in contact with soil is subject to possible accelerated rot.
A full metal bed has no wood in the framework to create that issue.
This article using raised garden beds discusses more details.
Metal raised garden beds are fantastic. They have a decent life span and are simple to make. Kit form garden beds from manufacturers like Birdies (from Australia) can be made into several different shapes through their modular format.
These beds come with a plastic clip-over edge protector strip that serves the purpose, and while this idea is good for the DIY, it is pretty expensive for similar edge protectors bought separately.
It is one thing to have garden beds available; filling them with quality soil can be different. We have an article on how we fill our beds with naturally made organic soil using chickens. You might find it helpful.
Sharp edges can and should be covered. Little fingers from children are at high risk.
Article by Tim Blanch for TheTropicalHomestead.com. He is a qualified Permaculture designer.
data reference for PE pipe lifespan link