Tools & How-To June 2026 · 11 min read

How to Design a Raised Bed: Size, Soil & Layout Guide

Dennis Mutahi

Landscape Design Writer

Raised beds solve the three most common growing problems at once: poor drainage, compacted soil, and back-breaking access. They warm up faster in spring, hold a custom soil mix, and let you grow intensively in a fraction of the ground-level space. This guide covers everything from dimensioning and material choice to soil blending and layout placement — so you build once and grow for years.

Raised garden beds with vegetables and flowers in a well-designed backyard layout

In this guide

Why Raised Beds Choosing Dimensions Materials Compared Soil Mix Layout & Placement What to Grow Visualise With Hadaa FAQ

Why Raised Beds Work

A raised bed is a contained growing area elevated above the surrounding ground level. The simplest version is a timber frame filled with soil. The most engineered version is a 60 cm corten steel planter with integrated irrigation. Both achieve the same core advantages over ground-level planting.

Drainage control

Water moves through a raised bed by gravity. Waterlogged clay soil — the number one vegetable killer in temperate climates — is no longer a factor. You control the drainage through your soil mix.

Custom soil

Ground soil takes years to improve. A raised bed lets you fill with the exact blend your crops need on day one. No double-digging, no pH lottery.

Warmer soil in spring

Elevated soil drains faster and warms earlier. Raised beds typically reach planting temperature 2–3 weeks ahead of ground-level soil in spring.

Accessible height

A bed at 60 cm eliminates bending entirely. At 45 cm it reduces strain significantly. For anyone with mobility limitations, a raised bed is not optional — it is the only practical growing method.

If you are planning an edible garden design, raised beds are the single most effective structural decision you can make. They define growing zones, create clear paths between crops, and make crop rotation physically obvious rather than theoretical.

Choosing Dimensions

Raised bed dimensions are driven by ergonomics, not aesthetics. The width is set by arm reach. The height is set by purpose. The length is set by available space and budget. Get the width and height right and the bed will serve you for decades.

Width: the reach rule

Accessible from both sides: maximum 120 cm (4 ft). You must be able to reach the centre without stepping on the soil. Stepping on raised bed soil compacts it and defeats the purpose.
Against a wall or fence: maximum 60 cm (2 ft). You can only reach from one side, so halve the width.
Wheelchair accessible: maximum 90 cm wide and minimum 60 cm high with a 60 cm clear approach on all access sides.

Height: by purpose

Height	Purpose	Best for
15–20 cm	Cosmetic edging	Defining flower borders on good existing soil
30 cm	Standard growing	Most vegetables, herbs, and annual flowers on open ground
45 cm	Deep root crops	Carrots, parsnips, tomatoes, or beds over compacted subsoil
60 cm+	Accessibility / container	Standing-height gardening, beds on concrete, wheelchair access

Length: practical limits

No ergonomic limit on length. Timber boards come in 240 cm (8 ft) lengths — build in multiples to minimise waste. Corten panels are typically 200 cm joined with brackets. A 240 × 120 × 45 cm bed holds ~1.3 m³ of mix; budget and delivery access set the practical cap.

Materials Compared

Material choice determines cost, lifespan, visual style, and maintenance. Every material below is food-safe for edible growing. The table compares them on the factors that matter most.

Material	Cost/m	Lifespan	Style	Maintenance
Pressure-treated softwood	$15–25	10–15 yrs	Informal / cottage	Re-stain every 3–4 years
Untreated hardwood (oak/larch)	$30–50	15–20 yrs	Natural / warm	None — silvers with age
Railway sleepers	$20–35	15–25 yrs	Rustic / heavy	Check for creosote leaching on older stock
Corten steel	$60–100	25+ yrs	Modern / architectural	None — self-sealing rust patina
Galvanised steel	$40–70	20+ yrs	Industrial / clean	None until zinc coating wears
Brick / block	$35–60	30+ yrs	Traditional / formal	Repoint mortar every 15–20 years
Natural stone	$80–150	Indefinite	Premium / heritage	None
Composite boards	$45–75	20–25 yrs	Contemporary / uniform	Wash annually

Different raised bed materials compared — timber, corten steel, and stone side by side

Decision shortcut

If budget is the constraint, use pressure-treated softwood — it gives 10+ years at the lowest cost per metre. If longevity and zero maintenance are the priority, corten steel or natural stone pay back over 25+ years with no upkeep. For a broader set of raised bed style ideas, see our guide to raised garden bed ideas.

Soil Mix

The soil you put in a raised bed matters more than the material you build it from. Ground-level garden soil compacts inside a raised frame because it lacks the natural worm and root activity that keeps open ground aerated. A purpose-blended mix solves this from day one.

General-purpose raised bed mix

60%

Quality topsoil

Screened, weed-free. Provides mineral content and weight to anchor roots.

30%

Mature compost

Well-rotted garden compost or composted green waste. Provides nutrients and organic matter.

10%

Sharp horticultural sand or perlite

Opens the structure for drainage. Prevents waterlogging in winter.

Heavy feeder mix (tomatoes, squash, brassicas)

Increase compost to 40% and reduce topsoil to 50%. These crops extract nutrients fast. Top-dress with 5 cm of fresh compost each spring before planting to replenish what the previous season consumed.

No-dig approach

Fill the bed with the standard mix and never turn it. Each autumn, lay 5–10 cm of compost on top as mulch. Worms incorporate it over winter. After 2–3 years, no-dig beds develop stable crumb structure that holds moisture and suppresses weeds.

Volume calculator

Length × width × depth (metres) = cubic metres needed. A 240 cm × 120 cm × 45 cm bed = 1.3 m³. Order 10% extra — the mix settles within the first month.

Layout and Placement

Where you place raised beds determines how much sun they receive, how easy they are to maintain, and how the garden flows around them. Placement mistakes are expensive to fix once beds are filled with 1+ tonne of soil.

Sun orientation

Run beds north–south so both long sides receive equal sunlight throughout the day. East–west beds shade the north side of the bed for most of the growing season.
Minimum 6 hours direct sun for vegetables. Place beds in the sunniest part of the garden, away from tree canopy and building shadows.
Tall crops at the north end of a north–south bed so they do not shade shorter plants behind them.

Path width between beds

Minimum 45 cm (18 in) between beds for walking access with a trug or bucket.
60–90 cm (24–36 in) for wheelbarrow access. At least one main path needs wheelbarrow width for soil delivery and harvest.
120 cm (4 ft) for wheelchair access between beds.

Proximity to water

Raised beds dry out faster than ground-level soil — the exposed sides lose moisture to wind and sun. Place beds within comfortable hose reach of a tap. If you plan more than 4 beds, run a simple irrigation spine (a single supply pipe along the main path) with drip lines branching into each bed. Watering by hand across 6+ beds becomes the task that stops people gardening in July.

For broader principles on placing elements within a garden plan, including how raised beds interact with other zones, see our full garden layout planning guide.

What to Grow in Raised Beds

Raised beds suit almost any planting scheme. The controlled soil and defined boundaries make them ideal for intensive cropping, cut flowers, herbs, and mixed ornamental displays.

Vegetables

Intensive square-foot planting works well — each 30 cm square gets one crop at optimal density. Rotate families annually. A single 240 cm x 120 cm bed produces enough salad for a household of four.

Cut flowers

Dahlias, zinnias, sweet peas, and cosmos thrive in rich, well-drained raised bed soil. Plant in rows 20–30 cm apart. Succession sow every 3 weeks for blooms June to October.

Herbs

Mediterranean herbs need sharp drainage — a raised bed with extra sand is ideal. Place near the kitchen door for daily harvesting. Mix perennial rosemary and thyme with annual basil and coriander.

Mixed ornamental

Combine structural evergreens with seasonal perennials and grasses. Raised beds elevate planting to eye level, making textural detail visible that would be lost at ground height.

Seasonal planning

Raised beds can produce year-round with the right succession plan. For a full seasonal approach including winter harvests, see our guide to DIY garden design step by step.

Visualise Raised Bed Arrangements With Hadaa

Deciding between timber and corten, 3 beds or 5, L-shaped or parallel rows — these choices are hard to evaluate in the abstract. Upload a photo of your garden to Hadaa and the AI renders raised beds placed in your actual space with accurate scale, material finishes, and planting arrangements.

Compare timber vs steel vs stone in the context of your actual garden
Test different bed configurations and path widths at true scale
See how planting fills the beds across seasons
Share the rendered layout with a contractor as a visual brief

The entire process takes minutes — upload, generate, compare, and download a contractor-ready image showing exactly what you want built.

Visualise My Raised Beds →

Frequently Asked Questions

What is the best width for a raised bed?

The maximum comfortable width is 120 cm (4 ft) for a bed accessible from both sides. This allows you to reach the centre without stepping on the soil. If the bed is against a wall or fence, cap width at 60 cm so you can reach the back row from the front edge only.

How deep should a raised bed be for vegetables?

Most vegetables need 30–45 cm of root depth. Carrots, parsnips, and tomatoes prefer 45 cm. Lettuce, herbs, and shallow-rooted crops manage in 20–30 cm. If you are building over concrete or compacted ground with no drainage below, build to at least 45 cm and add a 5 cm gravel drainage layer at the base.

What soil mix should I use for raised beds?

A proven general-purpose mix is 60% quality topsoil, 30% mature compost, and 10% sharp horticultural sand or perlite for drainage. For heavy feeders like tomatoes and squash, increase compost to 40% and reduce topsoil to 50%. Avoid using garden soil alone — it compacts in a raised structure and drains poorly.

Which material lasts longest for raised beds?

Corten steel and natural stone both exceed 25 years with zero maintenance. Brick and block last indefinitely when properly mortared. Pressure-treated softwood lasts 10–15 years. Untreated hardwood (oak, larch) lasts 15–20 years. Composite boards last 20–25 years but cost more upfront than timber.

How does Hadaa help visualise raised bed layouts?

Upload a photo of your garden to Hadaa. The AI generates photorealistic renders showing raised beds placed in your actual space — with accurate scale, material finishes, and planting arrangements. You can compare timber vs steel vs stone in context, test different bed configurations, and share the render with a contractor as a visual brief.

See Raised Beds in Your Garden

Upload Your Yard Photo — Visualise the Layout

Hadaa renders raised beds into your actual garden photo — accurate material finishes, correct scale, and planting detail. Compare configurations in minutes, not weeks. Every project includes a personal onboarding call so you get the most from your design.

Design My Raised Beds → See How It Works