How to choose steel thickness for your Garden Edging

When it comes to choosing the right steel thickness for garden edging, the ideal choice depends on several factors. Here’s an honest review of different steel thicknesses and what you will need to consider before making your choice. 

Compromise: How it Affects Steel Thickness

Before we consider some different options, let us start by asking why you are choosing between different steel thicknesses.  Is it:  

• Because of its strength?  
• Its aesthetics?  
• Budget?   
• Ease of installation?  
• Lead time?  
• Safety?  
• Durability?  
• Longevity?  
• Or something else?   

There are many things which could be influencing your choice, and it is important to understand what your priorities are. Often, you cannot have everything, so you must choose what you are prepared to sacrifice. One question that comes up often is, “If you can’t see the thickness of the steel and the edging system is suitable, does it really matter?”  

Or is there an option that does not compromise?... 

With that, let us look at some options:  

 

What Steel Thicknesses Are Available? 

Corten steel is available exclusively in sheet form, meaning all sections must be cut from sheets before being formed or welded. It comes in a wide range of thicknesses, from as thin as 0.5mm up to 40mm. For steel edging, 1 – 6mm is normally used.

Stainless steel and mild steel are also commonly available in standard sheet sizes across a range of thicknesses. 

For galvanized steel, it is available up to 5mm thick. Beyond this thickness, hot-dip galvanizing is usually preferred, as it offers better corrosion protection for thicker steel.  Thinner steel sheets may warp when hot dip galvanized due to the heat involved in the process. 

 

100 - 300mm Garden Edging

When selecting the best steel thickness for garden edging with heights ranging from 100mm to 300mm, the choice depends on the durability, soil pressure, and longevity you are aiming for. Here is a breakdown of which thicknesses work best for different applications: 

1.6 - 2mm Steel Thickness 

Ideal Application: Small vegetable or flower beds. 

Pros: 

• Offers a good balance between strength and flexibility. 
• Suitable for light-duty raised beds where soil pressure is moderate. 
• Easy to form curves onsite 

Cons: 

• Only suitable for straight installed edges up to 150mm high (unless formed for extra strength)  
• Hard to achieve straight edges  
• Can be moved out of alignment after installation. 

4mm Steel Thickness

Ideal Application: Ideal for raised borders, flower beds, lawns, and small paths. 

Pros: 

• Much more durable and resistant to bending or warping under soil pressure. 
• Long-lasting and provides a clean, professional finish. 

Cons: 

• Heavier and more difficult to handle, requiring more effort during installation. 
• More expensive than thinner options. 

6mm+ Steel thickness

Ideal Application: Ideal for driveways and can manage the largest burdens. 

Pros: 

• Extremely durable, capable of withstanding soil loads without warping or bending. 
• Ideal for heavy-duty residential applications where longevity is critical. 
• Provides a strong, premium look. 

Cons: 

• Much heavier and cannot be installed without some prefabrication.  
• May require onsite welding/fabrication. 
• Most expensive option, potentially overkill for home gardens. 

GEO SYSTEM: Groundline. Find out more here.  

 

300- 600mm Raised Beds 

Once we are over 300mm high, the weight of the soil acting on the edge becomes notable. At this point a formed system is usually preferable to ensure your edge design is suitable. Some other considerations if given the choice. 

Top edge vs no top return?   

If the retaining wall has a top return, the thickness of the steel cannot be seen. Therefore, providing the system is proven, thickness may not be a consideration.  Here we look at some other things you may want to think about if opting for a system with no top-edge return.

 

 

 

 

 

 

1. Sharpness and Safety: Without a top return, the exposed edge of the steel can be sharp. You may need to take precautions to avoid injury.  
2. Structural Integrity: The absence of a top return reduces the rigidity and strength of the steel edge. This may be an issue in high-traffic areas.  
3. Deformation: Without the additional support provided by a top return, the steel is more susceptible to deformation over time, especially in straight-edge installations. This is less of an issue to curved designs where deformation is hidden within curves.  
4. Corrosion at the Edge: A raw, exposed edge, without a return can be more vulnerable to corrosion.  A powder coated edge would chip easily, the steel will then rust more quickly along the thin exposed edge, reducing its lifespan and aesthetic appeal.  
5. Aesthetic Appeal, a matter of opinion: A straight-cut, unfinished edge might appear less refined than an edge with a top return, especially in high-end landscaping designs. On the other hand, an unfinished edge may provide a ‘cleaner’ edge which could enhance the design.  
6. Maintenance Challenges: Sharp, exposed edges are harder to maintain as they may catch debris or damage easily during regular garden upkeep. 

Contour solves all the above issues and more, whilst also retaining the aesthetic of a 7mm thick steel system... there is no need to compromise after all!  

GEO SYSTEM: Contour. Find out more here. 

 

600- 1200mm Retaining Walls  

600mm to 1200mm retaining wall heights call for a structurally approved system. Structural calculations are the numbers behind the confidence that a system is suitable for its intended purpose. At these heights, steel retaining walls have a lot of soil weight to withhold so it is more important that the system is proven.  

GEO SYSTEM: Anco. Find out more here. 

If given the choice, the considerations are like as we discussed for 300 – 600mm high edges. However, more pronounced. At these increased heights to counter the effects of removing the top edge, it is necessary to increase more than just the thickness of the steel.  

 

Conclusion  

Before we conclude, you will notice that most of our systems on GardenEdgingOnline.com do not even mention how thick the steel edge is! This is because we have done the research and testing and have selected thicknesses that are most suitable. Take Anco, we have full structural calculations which enable us to offer its lifetime guarantee! Thicker steel would add nothing to the system, thinner steel would fail structurally.  

Therefore, if given the choice, selecting the right steel thickness is critical! Hopefully, you now understand some of the main considerations which will help ensure your steel edge is installed to last! It’s tempting when budgets are tight to select a thinner gauge of steel but be aware it could be the difference between success and failure!  Our recommendation is a system that is proven, well thought out and suitable for every element of your project. 

GEO SYSTEM: Anco. Find out more here

GEO SYSTEM: Contour. Find out more here

GEO SYSTEM: Groundline. Find out more here