Raised Beds for Vegetables: Size, Soil and Siting Guide
How to plan and fill a raised bed for vegetables in the UK, including ideal size, materials, soil mix, siting, watering and what to grow first.
Raised beds make growing vegetables more manageable. They warm up faster in spring, drain better, keep you off the soil and give a defined space for crops. They are not magic, though, and the choices you make at the start affect how well they work.
Where to put them
Most vegetables need at least six hours of sun a day. Choose a spot that is:
- Sunny and sheltered from strong wind.
- Level, or easily levelled.
- Close to a water supply.
- Within easy reach of the house, so you actually use it.
Avoid positions directly under trees, where roots, shade and drips compete with your crops.
Size and shape
A bed that is about 1.2m wide lets you reach the middle from either side without stepping on the soil. Length is flexible, commonly 2 to 3m. Depth can be 20 to 30cm for most crops, more for carrots and parsnips. If you have back problems, taller beds around 60 to 80cm reduce bending, with a ledge to sit on. See also garden help for older homeowners.
Leave paths of at least 60cm between beds so you can get a wheelbarrow through.
Materials
- Untreated timber such as larch or cedar lasts longer than softwood. Sleepers are sturdy but heavy.
- Scaffold boards are cost-effective and easy to cut.
- Metal or composite panels are durable and low maintenance.
- Brick or stone is permanent but expensive.
Avoid old railway sleepers treated with creosote for edible crops, as they can leach chemicals into the soil. Check labels of treated timber to ensure it is suitable for growing food.
Preparing the base
On grass or weeds:
- Cut the turf or flatten weeds.
- Lay cardboard over the ground to suppress growth, overlapping edges.
- Place the frame on top and fix the corners securely.
- For moles or rabbits, lay mesh under the frame.
Do not line the base with plastic, which prevents drainage and root growth.
Soil mix
Fill with a blend that drains yet holds nutrients. A common mix is:
- Around 60 to 70 per cent good topsoil,
- Around 30 to 40 per cent well-rotted compost,
- A little grit if the topsoil is heavy.
Do not fill with compost alone; it settles and becomes depleted quickly. To fill a large bed economically, add coarse woody material or logs in the bottom layer and top with soil, the so-called hugelkultur approach. You can also see our guide to improve it with compost in the first year.
What to grow first
Start with reliable crops:
- Salad leaves and radishes: quick and forgiving.
- Beetroot and carrots: do well in the loose soil of a raised bed.
- Broad beans and peas: sow early and gain structure.
- Courgettes and runner beans: productive in summer.
- Herbs: parsley, chives, thyme and mint (keep mint in a pot).
Rotate crop families each year to reduce pests and disease.
Watering and feeding
Raised beds dry out faster than ground soil, so water regularly in warm weather, ideally in the morning. A thick mulch of compost or straw helps retain moisture; see watering your garden in hot weather. Top up with compost every spring and add a balanced organic feed as plants start to grow.
Common mistakes
- Beds too wide, so you step in them.
- Too shallow for root crops.
- Poor-quality fill that sinks and runs out of nutrients.
- Siting in shade.
- Forgetting protection from slugs and pigeons.
Getting someone to build them
If you prefer to buy the beds built and filled, a gardener or handyperson can do it, and you can plan the planting. On Compito you can search by postcode, compare ID-verified local providers and send a request with sizes and materials. See how it works.
Worked example: a first 2.4m by 1.2m bed
A beginner builds one bed from untreated timber boards, 25cm deep, on level lawn with cardboard beneath. Filling it with a topsoil and compost mix takes roughly three cubic feet per square foot of depth, which for a bed this size means a delivery of a few bags or a small bulk load. Materials and fill might cost in the region of £80 to £200 depending on timber and soil. They sow salad, radishes and beetroot in April, add runner beans at the back in May, and mulch with compost in June. By summer the bed gives regular pickings with about half an hour of care a week.
Material comparison
| Material | Lifespan | Notes |
|---|---|---|
| Untreated softwood | Several years | Affordable, replace eventually |
| Larch or cedar | Longer | Higher cost, good appearance |
| Scaffold boards | Several years | Easy and practical |
| Brick or stone | Decades | Permanent, higher cost |
| Metal panels | Long | Heat up in sun, durable |
Filling economically
Fill the base with branches, turf turned upside down and wood chips, then top with soil and compost. It saves money and recycles garden waste. Avoid compost-only fills that sink and run out of nutrients.
Special cases
- Rentals. A freestanding bed or large planters are easier to remove than dug-in structures.
- Clay or poor soil. Raised beds are particularly helpful here.
- Accessible gardening. Taller beds around 60 to 80cm high reduce bending; see garden help for older homeowners.
- Pests. Netting for pigeons and slug control keep early crops safe.
Year-two checklist
Top up with compost, rotate crop families, remove old plant debris and check timber for rot. Small annual care keeps the bed productive for years.
Frequently asked questions
How deep should a raised bed be?
Around 20 to 30cm suits most crops. Deeper is better for long root vegetables or if the ground below is poor.
Can I put a raised bed on a patio?
Yes, if it has a base and drainage and the surface can bear the weight. Wet soil is heavy, so check carefully, especially on balconies.
Do I need to replace the soil every year?
No. Top up with compost each year and rotate crops. Replace the top layer if disease builds up.