This post walks your through the steps to build your own raised garden bed using recycled materials, as well as how to fill them and maintain them for years of backyard harvests ahead!
Raised garden beds are easily my favourite way to grow vegetables. They look great, they retain moisture and they prevent grass and other weeds growing through your veggies. Raised garden beds can really optimise your use of space, and can be made in different shapes and sizes. They produce incredible results for many food crops from root vegetables to pumpkins to tomatoes and everything in between.
What is a raised garden bed?
A raised garden bed is pretty much what it sounds like – a garden bed that has been raised above ground level. They are usually constructed with solid walls to hold the soil within the bed. Raised garden beds can be any height, from 10cm above ground level up to waist height for easier access. If you have the garden space, raised beds are perfect for a vegetable garden, herb garden or ornamental garden.
What are the benefits of raised garden beds?
There are many benefits to growing in raised garden beds including
- Water retention – water tends to be held within the garden bed and made available to plants a little bit longer. Moisture can be concentrated into the bed rather than dispersed across the soil profile.
- Deeper soil profile – raised garden beds allow plant roots to extend deeper into the soil and utilise water and nutrients more efficiently.
- Reduced weed competition – helps to keep weeds and invasive grass out of your vegetable garden.
- Accessibility – raised garden beds are great for everyone, but especially for those with mobility limitations. Raised beds can be built to any height and customised for any ability ie wheel chair height/ hip height to reduce the need to bend and reach.
- Soil amendment – it is typically much easier to amend the soil in raised garden beds. The soil remains quite loose and workable, making it easier to add and incorporate things such as compost.
- They look great – there’s something about looking out the window at a raised garden, it draws the eye and puts your beautiful garden (and hard work) on display!
What are the best materials for building raised garden beds?
It’s important to choose the right materials to build a raised garden bed. You want to use materials that will last many years, continue to look great over time, and not leach anything nasty into you soil/food. I love using natural materials in the garden, its a great way to improve the look for an outdoor space.
When choosing timber, it is important to choose the right kind of wood. It’s a good idea to use hardwood or other rot-resistant woods that can tolerate getting wet and won’t break down too quickly. It won’t last forever, but it will last many years longer than alternatives such as pine. Avoid the use of untreated wood, as this will simply not last and will start to breakdown within 12 months. I don’t recommend using old pallets to make garden beds as the timber may be methyl bromide treated, which is a highly toxic compound used for fumigation.
Corrugated iron is a great material as it not only lasts many years, but actually looks better as it ages. I love the rustic look of corrugated iron in the garden.
A note on treated timbers
If using treated timbers, always double check that the method of treatment is safe to use in the vegetable garden. Older treatment methods involved the use of arsenic and other nasty chemicals, so beware when sourcing second hand materials.
More recent methods of treating timber are thought to be safer, but it is always worth researching to figure out what you’re comfortable exposing yourself and your soils to. Remember that you are growing edible plants/food crops, and if in doubt, I would recommend to choose another material.
Where to source reclaimed materials for minimal cost
As you know, I love a good bargain when it comes to sourcing materials. Here are a couple of ideas to get your started:
- Facebook marketplace – keep an eye out for materials popping up in your area. You can often negotiate a good price, or even find some free treasures.
- Scrap metal – if searching for corrugated iron, pop into your local scrap metal place to see what they have. If they don’t have exactly what you’re after, they might be able to keep you in mind.
- Clearing sales – when a property or farm goes on the market, they often have a clearing sale to clear out any materials or equipment. This is a great place to grab a bargain on timber or even some tools.
- Word of mouth – asking around may lead you to some great finds, and it never hurts to have people keep an ear out for you.
How to build a raised garden bed
Choose your materials
Hopefully you’re able to find some great reclaimed materials to build a raised garden bed. If not, you can always buy new. Either way it will be a good investment into your veggie growing passion.
For our raised garden beds, I used reclaimed corrugated iron, reclaimed hardwood timber, self-drilling screws, landscape fabric and reclaimed red brick. It’s always satisfying turning recycled materials into upcycled materials!
Source your tools and equipment
You will need some tools to complete the project. I used what we had and borrowed the rest from a friend. To build our corrugated iron beds I needed an angle grinder (for cutting corrugated iron), chainsaw (for cutting timber), drill (for attaching corrugated iron to timber), measuring tape and pen.
Safety is always important
I cannot underestimate how important it is to be careful and use adequate safety equipment.
If you don’t have these basics, this is the first place to start. Head to your local hardware store and invest in these important items.
- Safety glasses
- Ear muffs
- Gloves
- Long sleeves/pants
- Closed toe shoes/boots
If you don’t feel confident using power tools, please seek help from someone experienced. They may be able to give you a lesson to grow your confidence.
Measure and cut all your materials
It’s important to spend some time thinking about your garden bed design. If you have a lot of space, you may wish to design large raised beds. Alternatively, small spaces may benefit from a couple of smaller beds. Something to consider is the width of the bed – you need to be able to easily reach the middle from both sides, or the raised bed needs to be narrow enough to reach right across to the other side if only accessible from one side. Once you have your garden bed design written down and all your pieces planned out, it’s time to measure and cut your materials. I measured and cut enough to build one raised garden bed first, put it all together to make sure it worked, then proceeded to measure and cut the rest.
Putting it all together
This may require some extra hands. Start building your beds by joining all your pieces together. This will depend on your design, materials and equipment.
I used self-drilling screws to attach my short sides of corrugated iron to my timber corner pieces. I then used self-drilling screws to attach my long sides. Bracing timber lengths were added to some of the beds that needed reinforcing.
Suppressing grass and using landscape fabric
I decided to take off the top 10cm of soil/grass and partially sink my raised garden beds into the ground. I also decided to use some landscaping fabric/weed mat underneath my garden bed to suppress the grass. Weed mat is great as it allows good drainage to remove excess water.
If I were to do this again, I wouldn’t use weed mat or landscape fabric. These products are usually made from plastic and can cause microplastic pollution as they degrade. Instead, I would use a thick layer of cardboard to a few hessian bags to cover the bottom of the bed.
Check out my blog post for more tips on how to reduce unneccessary plastic in your garden.
The weed mat was extended out to 15cm on each side of the garden bed, folded up and held in place with reclaimed bricks. This also makes it much easier to mow, as you can guide the lawn mower wheels onto the bricks and really get the grass down.
I found this method worked really well and I haven’t had any issues with grass invading the beds.
How to fill your raised garden bed
One of the downsides to building raised garden beds is that you will need to fill them with fresh soil. You can usually find this at a garden supplies store/depot. Buying soil by the metre is significantly cheaper than buying soil in bags. Garden supply stores can usually deliver to you, and you will then need to move the soil yourself into the raised beds by wheelbarrow or bucket.
I chose to bulk out the bottom third of my raised beds with straw. Straw bales are usually affordable and readily available from garden supply or stock feed stores. I recommend against using hay bales as these will contain a lot of seed, which will add weeds to your garden beds. You can also add grass clippings and leaves as the base layer to your raised garden bed. Adding this base layer saves time and money (as you need less soil), as well as helps to feed the soil as the straw breaks down. I then added a good quality garden soil and compost blend from my local garden supply store to fill the rest of the beds. Soil quality is extremely important, always choose the best quality that you can afford. I then covered the soil surface with mulch and watered in well before planting.
If using soil that you already have on your property, make sure that it is good quality and low in weed seed, as this could potentially cause a headache down the track.
Maintaining your raised garden beds
As with any gardening method, your garden beds will require maintenance to ensure that the soil is healthy. Adding compost between growing seasons is a great way to boost the microbes and fertility in your soil. You can also add blood and bone, worm casting or worm tea to really give your soil a boost.
If you decided to use straw in the bottom of your raised garden bed, you will notice that after 6-9 months the soil in the raised garden bed will ‘sink’. This is because the straw has broken down over time, which is great because it adds organic matter, helps to feed the soil and improves drainage. In the first year, you will need to ‘top up’ your soil at the end of the growing season to make sure that your soil depth is adequate for the plant roots to reach their optimal depth. A good time of year to do this is either the end of summer or the start of spring.
My frugal tips
- Source your materials second-hand where possible – check out marketplace, clearing sales or use word of mouth to find a bargain.
- Don’t go and buy tools – ask around to see what you can borrow. Check out your local area for a ‘tool library’, these are becoming more common. You can borrow and return tools when you need them.
- Buy soil by the metre (or yard) – this is SO much cheaper than buying soil in bags.
- If you’re not ready to invest the time/money into building raised garden beds, check out my articles on how to grow food in pots and containers and how to start a sunken container garden.
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