13 Cheapest Ways to Fill Raised Beds

What Are The Cheapest Ways to Fill a Raised Bed?

Raised beds offer a great way of growing a huge variety of plants; from colourful flowers to delicious veggies and fragrant herbs. But while you may think the hard work is done once your new raised bed has been built and installed, you’ve still got to fill it. 

Filling a raised bed garden with the best soil you can get your hands on can cost a lot of money, especially if you’ve got a few raised beds or the bed you’ve built is very large. 

Fortunately, there’s plenty of materials that can be sourced cheaply (or even for free!) and used to fill your raised garden beds. Even better, many of these materials can benefit your plants – improving poor soil, aiding plant growth and, if you’re growing edible produce, leading to a better harvest! 

Let’s take a look at some of the cheapest ways to fill raised beds. 

1. Homemade Compost

Topping up your raised bed with homemade compost will improve the quality of your soil, adding nutrients while also helping you to make the most of household waste.

Making your own compost is a slow process, but it’s arguably the cheapest way to fill your raised bed, as you only need to use waste products. While bags of compost can be picked up at garden centres, building your own compost pile is far more cost-effective. 

To make your own compost, combine green and brown waste materials in a compost bin (which can be made out of pallets), then add water and aerate regularly. 

Green materials to use include grass clippings, food scraps and coffee grounds, while brown materials include fallen leaves, twigs and hay. 

Once the pile dries and stops giving off heat, it can be mixed with topsoil then used to fill your raised beds. 

2. Manure

Proper use of manure in your raised beds can add vital nutrients to your soil and plants, including nitrogen, phosphorus and potassium. It can also improve soil structure, increasing its water holding capacity and enabling good drainage. 

So really, we should all be using manure in the garden!

If you’ve got livestock or know someone who has, getting hold of some manure should be fairly easy. Well-rotted horse manure is the best option, and this can be spread over the soil in early March.

Other good options include chicken, rabbit, cow and goat manure. These are full of nutrients and are relatively easy to get hold of. Bear in mind that if you are growing vegetables, you should never use fresh manure, as this can lead to contamination. 

To use manure in your garden, simply add a few inches to the top of your raised bed, then work it into the soil using a rake. 

3. Hugelkultur

One way of filling a raised bed without spending a lot of money is to use the Hugelkultur method. 

This gardening practice involves burying rotting debris underneath the soil, around 10″ to 12” deep. Debris that can be used includes large logs, sticks and organic matter. Using large pieces will ensure they break down very slowly.

In between the large pieces of material, add smaller matter such as grass clippings, dried leaves and wood chips. Once the gaps have been filled, thoroughly water, then add soil on top to fill the rest of the bed.

This method creates a sponge-like effect underneath the soil. As the matter breaks down, it holds water and nutrients, allowing the plants to collect what they need. 

Once the material has fully broken down, a microclimate is created underneath which will warm the soil, so you may even get a head start when it comes to your planting. 

4. Coconut Coir

With the move towards peat-free alternatives well and truly underway, many gardeners are opting to use coconut coir as opposed to peat moss to fill their raised garden beds. 

Coconut coir can absorb up to ten times its weight in water, which means it’ll help keep your plants hydrated.

Mixing coconut coir with compost at a 50/50 ratio makes a great starting mix for your seeds. For a high quality soil mix, go for 40% soil, 30% compost, 20% coconut coir and 10% worm castings. 

Coconut coir can be picked up from garden centres, and is relatively inexpensive when purchased in compressed form. 

5. The Ruth Stout Method

Put together by Ruth Stout or as she’s otherwise known ‘The Mulch Queen’, the Ruth Stout gardening method involves using organic matter to enrich the soil. 

While seen as revolutionary for a period of time, the concept is actually very simple. Natural debris such as leaves, hay, twigs, tree branches and kitchen scraps can be added to your raised bed to mulch the soil. There’s no equipment needed, simply large amounts of organic matter. It’s inexpensive, and should also save you a lot of labour. 

To fill your bed using this method, place a thick layer of organic matter on the soil, then spread around 8″ to 12” of soiled hay on top of it. 

The hay will decompose over time and enrich the soil. 

6. Core Gardening

Another gardening method that can be used to cheaply fill your raised beds is core gardening. Using this technique can help your soil to retain water better, while your plants may also develop stronger roots and be more resistant to disease. 

Core gardening involves digging a trench around 10” deep into your raised bed – ideally in the very centre. 

Add cardboard to the bottom, then fill the ‘core’ using wet, organic material such as leaves, grass clippings, old twigs, straw or hay. 

Once the core has been filled, water it thoroughly and fill the rest of the bed with soil. A 50/50 mixture of garden soil and compost should be suitable for the remainder. 

The section in the middle will break down, adding nutrients to the soil which can then be used by your plants. 

While this method can be repeated every year, it’s not necessary. So long as you add mulch and compost each year, your soil should stay healthy. 

7. Lasagna Gardening

Lasagna gardening has nothing to do with pasta or cheese, but it does involve a lot of layers!

This gardening method involves filling your raised bed with layers of organic matter. The material will break down and turn into rich, healthy soil that’s perfect for planting. Essentially, your raised bed will become one great quality compost heap!

Include a range of green and brown materials, such as newspaper, cardboard, leaves, grass clippings and twigs. 

The first layer is usually cardboard or newspaper. 

Next, add high carbon materials such as dried leaves, coconut coir and straw, followed by a layer of high nitrogen materials such as grass clippings, vegetable scraps, coffee grounds and manure. 

The green layer should be around ¼ as thick as the brown layer. 

Continue to layer brown and green material until your raised bed is filled. 

From here, you can either wait for the matter to break down, or cover with a layer of compost if you want to get planting immediately.

This method is not only very good for your plants, it’s also very affordable. Most of the material can be sourced either from your kitchen or garden, which makes it a lot cheaper than purchasing bagged soil. 

There’s a few disadvantages. If you’ve got a lot of raised beds, it can be hard to find enough organic materials.

It also takes a long time for the materials to break down. While it’s breaking down, it can be a bit of an eyesore!

8. Straw

Some gardeners are opting to use straw as mulch in garden beds. This will compost into nutrients which can then improve the quality of your soil. 

There is a risk, however. Some straw bales may contain weed seeds. You should ensure the straw bales you purchase are weed-free, otherwise you risk introducing weeds to your garden beds. 

Break the bale of straw into pieces then add a layer around 4” deep to the top of your raised bed. Don’t use it right up to the plant stem – leave a few inches of space around each plant. 

Straw can also be used as a lining at the bottom of your raised bed. Adding a thick layer should help improve your soil quality over time, while also preventing weeds growing up from underneath. 

9. Newspapers and Cardboard

Most gardeners choose to line their raised beds before adding soil or compost, and this can be done using either newspapers or cardboard, both of which are readily available and inexpensive to source. 

Lining your bed can prevent weeds from growing up from the bottom, and can also improve the drainage. Newspaper and cardboard will break down over time, improving the quality of your soil. 

Before filling your raised bed, place a few layers of newspaper or a layer of cardboard to the bottom. Add soil on top, and then it’s ready for planting. 

While newspaper ink won’t damage your plants, you should ensure that you don’t use glossy and colourful cardboard (for example the cardboard used in cereal boxes). This can release toxins into the soil. 

10. Grass Clippings

Grass clippings can also be used as mulch in your raised beds. Instead of disposing of your clippings after mowing your lawn, use them to fill your beds!

Grass clippings provide the soil with nutrients which can help prevent weed growth and preserve moisture. Adding them to your raised beds can reduce the amount of water and fertiliser that you need to use in the growing season 

It’s best to add grass clippings to the tops of your raised beds, once your plants have become more established. Spread a 2-3” thick layer near the base of your plants. 

Try to use dry grass clippings, as fresh ones may slow drainage and prevent oxygen from getting down into the soil. 

As the clippings decompose, the height of your bed will drop. Keep adding more throughout the growing season.

Another option is to line the bottom of your raised bed with grass clippings. 

Add a thick layer to the bottom of the raised bed, then pile soil on top. The weight of the added soil will cause the grass clippings to compact, meaning weeds won’t have enough space to grow up through the bottom. 

11. Fallen Leaves

Garden waste products such as fallen leaves can make a great base layer for your garden beds. 

If you’ve got a large tree in your garden, make the most of fallen leaves by collecting them and using them in your raised beds. 

Leaves will add brown, high carbon material to your compost, but they can also be added directly to the soil. Many gardeners choose to shred their leaves first, then add a 2 – 3” thick layer to the tops of their beds. Try not to let the leaves directly touch the stems of the plants.

This mulch can help to retain moisture, maintain a consistent soil temperature and limit the germination of weeds. As the leaves break down, nutrients will be added to the soil. 

Fallen leaves can also be used for the base of your raised garden beds. They will decompose at the bottom, adding organic matter to the soil. Add a thick layer of leaves to the bottom of your bed, then place your soil on top. 

12. Perlite

One ingredient that makes a huge difference when added to raised beds is perlite. This natural, organic material can help to prevent the soil from becoming too compact. Soil that’s very compact will block water and air from reaching the roots of the plants. 

Perlite is a lightweight, granular material made from expanded volcanic glass. It’s extremely porous, so it both holds water well and improves drainage. 

When planting your raised beds, add a cup or two of perlite and work it into the soil. 

Perlite is widely available at garden centres but it can be pricey. If you’ve got a lot of raised beds and don’t have the budget for perlite, opt for coarse sand instead. 

13. Soil Bought in Bulk

If you do need to purchase soil at a garden centre, try to buy it in bulk instead of in individual bags. Multiple, smaller bags of soil can work out very expensive, especially if you’ve got a lot of raised beds to fill! Many garden centres offer discounts if you’re able to purchase a lot of soil in one go.

The average shelf life of soil is around 6 months once opened, while unopened bags should stay in good condition for up to two years.