Building your own raised aluminum garden bed: The ultimate DIY guide

Reading time approx. 8 minutes

A raised bed is a space-saving and back-friendly way to grow vegetables, herbs, or flowers. A construction made of aluminum angle profiles and boards makes it particularly durable and stable. The aluminum profiles form the edge finishes, while the boards serve as the side walls.

In this guide, we will show you how to build a raised bed yourself using aluminum angle profiles. You will learn about the advantages of this construction method, which materials you need, and what you should consider regarding planning, assembly, and filling.

Content

• Why a raised bed with aluminum angles?
• Location & Planning
• Which aluminum profiles are used?
• Suitable Products
• Material List
• Step-by-Step Instructions
• Filling the Raised Bed Correctly
• Raised Bed with Cold Frame Attachment
• Tips for Longevity
• Aluminum Angles & Boards vs. Pure Wood
• FAQ

Why a raised bed with aluminum angles?

A raised bed with aluminum angle profiles and boards combines the advantages of both materials: the boards provide a natural garden aesthetic, while the aluminum angles protect the corners, stabilize the frame, and provide a neat finish.

The most important advantages:

• stable edge finish due to aluminum angles
• neat and modern outer edges
• boards remain visible as natural side walls
• aluminum does not rust like steel and is well-suited for outdoor use
• simple bolting without welding
• customizable in size and location

Additionally, a raised bed allows for back-friendly gardening. Due to the raised working height, you have to bend over less, can reach your plants better, and can manage bed maintenance, sowing, and harvesting much more comfortably.

Important regarding thermal behavior: Aluminum conducts heat more strongly than wood. Since only the edges are made of aluminum in this construction and the side surfaces are built from boards, the warming is less than in a raised bed with all-metal sides. In very hot locations, however, a light-colored surface or a semi-shaded spot may still be sensible.

Location & Planning for Your Raised Bed

Before you build your raised bed, you should determine the appropriate location. For vegetables, herbs, and many flowering plants, a sunny to semi-shaded spot is ideal. Also, make sure that the raised bed is sheltered from the wind and is easily accessible.

Important points for planning:

• level and load-bearing ground
• sufficient sunlight
• short path to the water supply
• enough space to work around the bed
• appropriate size for garden, balcony, or terrace

Recommended dimensions:

• Height: approx. 70–100 cm
• Width: maximum 120 cm so that you can easily reach the center
• Length: customized according to space availability

Note: A fully filled raised bed can weigh several hundred kilograms depending on its size. Therefore, on a balcony or roof terrace, the permissible load capacity should definitely be checked before assembly.

Which aluminum profiles are used?

For this construction method, you use 35x35 mm aluminum angle profiles with a 2 mm wall thickness. The angle profiles are mounted on the four vertical corners and serve as a stable edge finish. Additionally, they can be used on the top edges to protect the boards and give the raised bed a clean look.

The side surfaces are created from boards that are bolted between or onto the angle profiles. This creates a stable frame with a natural look and resilient aluminum edges.

Anodized or coated aluminum angle profiles are recommended for outdoor use. You can find more about this in our article on anodizing.

For the outdoor area, stainless steel screws are particularly suitable as they are corrosion-resistant and can reduce contact corrosion.

Suitable Products for Your Raised Bed

Material List for a Raised Bed with Aluminum Angles and Boards

For a stable DIY raised bed, you will need the following materials depending on the desired size:

• 4 × 35x35x2 mm aluminum angle profiles for the vertical corners
• Boards for the side walls, e.g., larch, Douglas fir, or black locust
• optional: aluminum flat profiles for internal reinforcement of long sides
• stainless steel screws for attachment
• drill bits suitable for aluminum and wood
• measuring tape, square, and pencil for marking
• hacksaw or custom-cut
• wood saw, if the boards are to be cut yourself
• vole mesh for the bottom
• garden fleece or foil
• compost and raised bed soil

Example for a simple construction:

• 4 × aluminum angle profile 35x35x2 mm as vertical corner posts
• several boards per side, depending on the height and length of the raised bed
• stainless steel screws for attaching the boards to the angle profiles
• optional flat profiles inside if longer sides are to be additionally stabilized

Many aluminum profiles can be ordered directly to size. This saves you time on cutting and provides clean edges for quick assembly.

You can learn more about suitable materials and properties in the article on aluminum alloys.

Building a Raised Bed from Aluminum Angles and Boards – Step by Step

1. Determine dimensions

First, determine how high, wide, and long your raised bed should be. For comfortable working, a height between 70 and 100 cm is recommended. The width should be a maximum of about 120 cm so that you can easily reach the center of the bed.

2. Prepare aluminum angle profiles

Cut four 35x35x2 mm aluminum angle profiles to the desired height or order them directly to the matching size in our shop. These profiles form the vertical corners of the raised bed and simultaneously serve as a stable edge finish.

3. Cut boards

Cut the boards to the desired length. For each side, several boards are placed on top of each other until the desired raised bed height is reached. Ensure all boards are cut cleanly and evenly.

4. Mark drill holes

Place the boards against the aluminum angle profiles and mark the drill holes. The screws should be evenly spaced so that the boards are securely connected to the angles.

5. Pre-drill aluminum angles

Pre-drill the marked spots in the aluminum angle profiles. Use a suitable metal drill bit for this. Pre-drilling facilitates assembly and prevents screws from being set at an angle.

6. Bolt side walls

Bolt the boards to the aluminum angle profiles. Start with one long side and then attach the short sides. Regularly check whether the corners are square.

7. Close the frame

When all four sides are connected, a closed rectangular frame is created. Tighten all screws and check if the raised bed is stable.

8. Optional: Mount flat profiles for reinforcement

For long side walls, aluminum flat profiles can be mounted on the inside. They additionally stabilize the boards and prevent the sides from bulging outward due to earth pressure.

9. Prepare the ground and insert vole mesh

If the raised bed is placed directly on earth or lawn, you should insert a vole mesh on the bottom. It protects the plant roots from rodents.

10. Line the insides

With this board construction, an inner foil or garden fleece is useful to protect the wood from permanent moisture and reduce soil leakage. Ensure that water can still drain well.

When combining different metals, a separating layer may also be useful to avoid contact corrosion.

11. Fill the raised bed

After assembly, the correct filling follows. The layer structure determines how well water drains and how many nutrients are available to your plants.

Filling the raised bed correctly – the optimal layer structure

A raised bed should not simply be filled with earth. The classic layer structure ensures better drainage, more nutrients, and natural heat development through decay.

Proven structure for vegetables and herbs:

1. Branches and brushwood as a drainage layer
2. Green waste, leaves, or upturned sod
3. half-ripe compost or garden waste
4. ripe compost
5. high-quality raised bed soil or potting soil

The lower layers decay slowly and release heat and nutrients in the process. This creates a particularly good microclimate for vegetables, herbs, and many flowering plants.

Since the raised bed will settle over time, you should refill earth or compost annually. After a few years, it may make sense to completely renew the layer structure.

Using a raised bed with a cold frame attachment

With a cold frame attachment, you can use your raised bed earlier in the year. A transparent cover stores heat and protects young plants from frost, wind, and heavy rain.

Popular extensions are:

• Raised bed with cover
• Raised bed with lid
• Cold frame attachment made of polycarbonate
• Slug protection
• additional intermediate shelves or storage

Due to the aluminum angle profiles, an attachment can be easily fastened or retrofitted later.

Tips for long-lasting raised beds with aluminum angles

• use 35x35x2 mm aluminum angle profiles as a stable corner solution
• use weather-resistant boards or appropriately treated wood fillings
• use stainless steel screws
• cleanly pre-drill drill holes
• protect boards inside with foil or garden fleece
• avoid waterlogging
• level the ground before assembly
• regularly check screws
• refill earth annually
• cleanly deburr open edges

If you would like to learn more about aluminum surfaces, you can find more information here regarding surfaces.

Aluminum angles & boards vs. pure wood – which material is better?

The combination of aluminum angles and boards is ideal if you want to combine a natural wood look with stable, clean, and durable edges. Compared to a pure wood raised bed, the corners in particular are better protected and more dimensionally stable.

FAQ about raised beds with aluminum angles