How to Plan a Modular Corten Steel Raised Bed: Layouts & Sizing Guide

A modular Corten steel raised bed is built from straight panels and corner sections that bolt together, so you can plan any shape — a simple rectangle, an L-shape, or a full kitchen garden layout — before you order a single piece. Here's how to plan it properly.

Step 1: Sketch your footprint

Measure the space and draw the outline to scale, in 500mm or 1000mm increments to match panel sizing. Straight CortenGrid panels come in 1000mm and 1500mm lengths; corner sections handle 90-degree inside and outside turns for L-shapes and enclosed beds.

Step 2: Choose your height

• 200mm — a low border or edging-style bed, good for shallow-rooted planting.
• 400mm — the most popular height, comfortable for most vegetables and no-dig gardening without bending too far.
• 600mm+ — accessible, back-friendly growing for anyone who struggles to kneel, or for deeper-rooted crops.

Step 3: Count your panels

Add up the total run length of each side and divide by your chosen panel length, adding corner sections wherever the layout turns. For an enclosed rectangular bed you'll need four corners (inside corners for a simple box); an L-shaped bed needs a mix of inside and outside corners depending on the turn.

Step 4: Plan for soil and drainage

Modular beds are open-bottomed, so they sit directly on your existing soil or a prepared base — good news for drainage and for deep-rooted plants that benefit from reaching the ground beneath. Fill with a mix of topsoil and compost, allowing for settling over the first season.

Frequently asked questions

Can I extend a modular bed later?

Yes — that's the main advantage of the modular system. Add further straight or corner sections at any time to extend or reshape your layout.

Do I need tools to assemble it?

Panels bolt together with basic hand tools — no welding or specialist equipment required.

Is a modular raised bed safe for growing vegetables?

Yes — see our detailed guide on Corten steel and vegetable growing.

How does it compare to a solid trough planter?

A trough planter is a fixed size and shape; the modular system is for anyone who needs a bespoke footprint or plans to expand later. See our full planter buying guide for a side-by-side comparison.

Start planning your layout

Browse straight and corner CortenGrid sections from £70, made in Britain and ready to build any shape you need.