Raised garden beds: how to build and maintain - Which? (2024)

Raised beds allow you to improve your garden soil, or even grow crops where there’s no soil at all.

Most people use wooded-sided beds, but you can create a raised bed by just putting a thick layer of garden compost on the soil and topping it up every autumn.

Breathe new life into your outside spaces.Sign up for our Gardening newsletter, it's free monthly

The advantages of raised garden beds

The main advantage is that when your soil is poor that extra 15cm of soil that the raised beds provide makes all the difference, particularly as it’s topped up with soil improver regularly. The surface dries out and warms up quicker in spring, so you can also get ahead with early sowings.

The growing areas are differentiated from the paths, so the soil in the beds remains loose and easy to plant into. The paths can be mulched with wood chips and kept weeded. Most raised beds are no wider than 1.2m as this allows you to reach into the centre of the bed from the sides when planting, weeding, watering and harvesting so you don't ever need to tread on the beds. This width is also easy for you to protect from insects with fine mesh or from cold with fleece.

Discover ourBest Buy frost protective covers

Raised garden beds: how to build and maintain - Which? (1)

If you want raised beds on a hard surface, raise the sides to at least 30cm or preferably higher to give plants a decent depth of soil. Taller raised beds are also useful if you have trouble bending or kneeling, or garden from a wheelchair.

The wooden sides can be a hiding place for slugs and woodlice so be vigilant.

Which? Gardening Magazine

Expert advice through the seasons so you know what to do and when. £4.99 a month, cancel anytime.

Sign up now

Raised garden beds: how to build and maintain - Which? (2)

Best Buy raised garden beds

Raised beds kits are increasingly popular for growing vegetables because they look neat and can make cultivation easier. You can make your own, but if that seems like a challenge too far there’s such a huge choice of kits it can be hard to know what type you should go for. Our Best Buy are the most robust beds that gave the best results.

Best raised bed kits

When testing raised bed kits, we looked for the products that were easy to build, robust and attractive. They also had to give us a great crop of veg.

Which? members canlog innow to see the full results and which are our Best Buys. If you’re not a member, join Which?to get instant access.

ProductOverall scoreInstructionsEase of constructionStructural strengthAppearance of bedEase of usePotato conditionPotato weightFinal condition*
Forest Garden Caledonian rectangular raised bed, wooden








Forest Garden raised bed builder pack, wooden








Garden Gear Original Veggie bed, metal









Garden Life metal raised garden bed kit








Garden Skill Build a bed 250mm raised bed kit, plastic









Greena Rectangular raised bed, wooden









Harrod Horticultural Allotment wooden raised bed kit, including capping









Overall rating The more stars the better. Ignores price and is based on: Clarity of instructions, 5%; Ease of construction, 10%; Structural robustness, 20%; Appearance of bed, 10%; Ease of use, 15%; Potato condition, 10%, Potato weight, 10%; Final condition, 20% *The condition one year after being constructed

Best materials for making a raised garden bed

You can buy ready-made raised beds, but if you want to save money, you can build your own bed.

Which? Gardening magazine trialled making beds from different materials to see how they compare.

Only Which? members cansee the full results of the two materials on test.

Material one and material two will be revealed once you log in.

If you’re not a member,join Which?to get instant access.

Material one

Material one pros:

  • The long length of this material meant that we only had to buy two to cut down for the size of our beds.
  • At 23cm-wide, they were also bigger than most of the other materials we tried. This gave the bed a good depth of soil to plant in to.
  • The bed looked strong, and when first built it gave the impression it would last for years.
  • The material faded a bit in the 18 months they were outside, but the only sign of deterioration was a bit of movement away from the fence post in one corner.
  • This bed gave the best yield of vegetables, particularly potatoes.

Material one cons:

  • This material were among the heaviest to work with.
  • The visual appeal of the otherwise chunky and robust-looking beds was also reduced.
  • The long length of the material makes it difficult to get home in a car, so you may need to pay to have them delivered.

Material two

Material two pros:

  • Inexpensive
  • As they were already sold in the length we required, we didn’t need to cut them down to size.
  • They were solid enough to screw together without needing a corner post. This reduced the installation time.
  • This material was easy to screw together and created a solid bed with a good depth of soil to plant in to.
  • The construction was solid and the material showed no signs of rot, warping or soil seepage, even after 18 months.
  • The yield of crops was satisfactory.

Material two cons:

  • You’ll need a long drill bit to create the pilot holes to screw together this material.
  • The thickness means the bed takes up slightly more space and also reduces the internal planting area.
  • The bed retained moisture well, but made the soil a bit wet and heavy to dig in spring.
  • Delivery charges for this material can be high.

Tips for making a raised garden bed

Raised garden beds: how to build and maintain - Which? (3)
  • Although 15cm is typically considered a reasonable height for a raised bed, you might prefer to build out of a slightly wider plank, which will give you a bit more depth of soil.
  • Strong corners helped to keep our beds in good condition – use 10 x 10cm fence posts rather than thinner battens to build a strong structure that will last.
  • Use screws rather than nails to build your bed. Nails will pull away from the corner posts more easily.
  • Restrict the width of your bed to 1.2m to ensure that you can easily reach the plants in its centre without having to stand in the bed.
  • None of the prices for our beds include the cost of delivery for materials. This ranged from £7.50 to £55, so is worth factoring into the cost of your project if you can’t collect the materials yourself.

What to fill raised garden beds with

Choose the wrong filling and you can end up with a bed that’s saturated in wet weather and slumps to create a compressed, airless mass with a hard crust that’s tricky to dig, or a mix that is so free-draining that your plants become parched in dry weather.

Which? Gardening magazine trialled different soil mixes to find the best recipe.

Best soil mix for raised garden beds

The best soil mix

  • Log in orjoin Which?to reveal the soil mix.
  • This mix excelled in most areas, giving us the biggest and healthiest-looking plants and best yields of potatoes and baby carrots.
  • Although the mix was quite heavy to put in the bed, it did not settle much and was very easy to dig.
  • It was easy to weed by hand without leaving roots behind. Soil fertility was good, and the pH around neutral.
  • The amount of moisture in the mix was well balanced, and it also had the warmest soil temperature – on average 1.5°C warmer than the ground temperature in the early part of the year

A soil mix worth considering

  • Log in or join Which? to reveal the soil mix.
  • They settled the least between autumn and spring, and the soil was on average 1.3°C warmer than the ground.
  • The mix also had a more neutral pH of 7.4than soil-only, and was just a little low in phosphorus when we tested it in the autumn.
  • The beds were easy to dig and weed, but could be drier than our best mix.
  • The yield of carrots was average, but the yield of potatoes was good.

The worst soil mix

  • Log in or join Which? to reveal the soil mix.
  • The average temperature was barely warmer than the ground, and it became so wet and heavy during the soggy spring that we had to delay planting our potatoes until it was workable.
  • Weeds snapped off when pulled, leaving their roots behind.
  • Soil fertility tests in autumn revealed that the soil had an alkaline pH of 7.9 and was lacking in nitrogen, phosphorus and potassium.
  • Despite adding NPK fertiliser in spring, the plants looked smaller and paler in these beds and produced the lowest yield of potatoes and carrots.

Discoverhow to grow a range of different veg

Raised garden beds: how to build and maintain - Which? (2024)

FAQs

What do you put in the bottom of a raised garden bed? ›

To put it simply, you should put a layer of organic material at the bottom of your garden bed, which will break down and enrich the soil. This can include compost, or woody material such as logs, dry wood, branches, and leaves.

How do I keep my raised beds soil healthy? ›

There are many choices that fall under this category but my favorites include the following:
  1. 1) Add Compost to Your Garden Beds. My number one go to choice always. ...
  2. 2) Shredded Leaves and Wood Chips Help Your Soil. ...
  3. 3) Worm Castings Improve Soil Health. ...
  4. 4) Add Nitrogen to Garden Beds.
Oct 21, 2023

Do raised beds need new soil every year? ›

“But even the best of gardeners will need to refresh the raised bed eventually. Settling soil is simply a fact of raised bed gardening.” Annually, topdressing with a few inches of compost or high-quality topsoil into raised beds should be enough to keep up with the settling soil level, Enroth says.

Should I put landscape fabric under a raised bed? ›

Water doesn't gush out of the raised bed as quickly. Prevents nutrient loss: Soil loss from watering can lead to nutrient loss too. Using landscape fabric as a raised bed liner prevents erosion and minimizes nutrient loss risk. The liner is especially useful for maintaining water-soluble nutrients from the soil.

What are three mistakes to avoid when gardening with raised beds? ›

What Are 3 Common Mistakes to Avoid When Gardening with Raised Beds?
  • Overcrowding Plants. One of the most common mistakes made when gardening with raised beds is overcrowding plants. ...
  • Using Poor Quality Soil. Another common mistake when gardening with raised beds is using poor quality soil. ...
  • Neglecting Watering and Drainage.
Mar 11, 2023

Why put cardboard in raised beds? ›

You can line the bottom of your raised garden bed with cardboard and newspaper to block out weeds or act as a barrier against rhizomatous, weedy or invasive plants. While some may opt for landscape fabric, cardboard is a more cost-effective option.

What are the disadvantages of raised garden beds? ›

The cons of raised beds

The soil mix also can be a significant, albeit one-time, expense. Raised beds need water more often since the soil is more exposed to air and dries quicker. Similar to growing in containers, the extra watering can leach nutrients out of the soil quicker than in-ground gardens.

How deep should a raised garden bed be? ›

The Best Height for Raised Beds

Keep in mind that beds 18 inches deep or more will have better drainage than shorter beds. While most plants don't need anything deeper than 18 inches, I prefer beds that are two feet deep (24 inches). The extra height is mostly just for the ease and convenience of the gardener.

What vegetables grow best in raised beds? ›

Carrots, beets, and radishes are some of the root vegetables that will really benefit from the improved soil. Spinach, chard, arugula, kale, and lettuce are some leafy greens to plant in raised beds. These quick-growing greens can be planted together or interplanted with other vegetables.

Can you reuse soil in a raised bed? ›

Yes, you can reuse a raised bed! You'll just need to refresh the nutrients in the soil to replace all the nutrients used up last year.

What is the best fertilizer for raised garden beds? ›

Most gardeners should use a complete fertilizer with twice as much phosphorus as nitrogen or potassium. An example would be 10-20-10 or 12-24-12. These fertilizers usually are easy to find. Some soils contain enough potassium for good plant growth and don't need more.

What is the best fill for raised beds? ›

Bagged raised bed potting mix is commonly used in small raised beds, but you can purchase it in bulk from local landscape companies. Another option is to make your own potting mix by blending equal parts of topsoil, compost, and sand to create a quality mix that's appropriate for most vegetables, herbs, and flowers.

How do you extend the life of a raised garden bed? ›

It's best to use untreated wood to build your raised garden beds, preferably a type of wood that won't decay quickly, such as cedar, redwood, or hemlock. Both the type of wood that you might find for sale and its affordability will vary based on where you live.

How do I protect my raised garden bed? ›

First, there are two covering materials that are most recommended for protecting gardens from animals and other pests: chicken wire and polypropylene mesh. Since hungry critters can become aggressive when it comes to acquiring food, securing your garden's chicken wire or mesh net is of the utmost importance.

How do I keep my raised garden bed from drying out? ›

Raised beds are likely to dry out faster due to airflow than beds in the ground. Adding a layer of absorbent materials like shredded newspaper and cardboard to your bed will help retain moisture in the soil. A good blend of compost and a layer of mulch on top of your bed will also help reduce the rate of evaporation.

Do I need to seal my raised garden bed? ›

Do I Have to Seal a Wood Raised Bed? Using an eco-friendly wood treatment is a great way to increase your confidence that your raised beds will last a long time. I recommend at the very least coating your lumber in linseed oil or beeswax to preserve them for the long haul.

References

Top Articles
Latest Posts
Article information

Author: Jeremiah Abshire

Last Updated:

Views: 6173

Rating: 4.3 / 5 (74 voted)

Reviews: 89% of readers found this page helpful

Author information

Name: Jeremiah Abshire

Birthday: 1993-09-14

Address: Apt. 425 92748 Jannie Centers, Port Nikitaville, VT 82110

Phone: +8096210939894

Job: Lead Healthcare Manager

Hobby: Watching movies, Watching movies, Knapping, LARPing, Coffee roasting, Lacemaking, Gaming

Introduction: My name is Jeremiah Abshire, I am a outstanding, kind, clever, hilarious, curious, hilarious, outstanding person who loves writing and wants to share my knowledge and understanding with you.