Raised garden beds also make tending your crop easier because you don’t have to bend down or do any heavy digging.
Why build a raised garden bed?
There are many reasons why you would want to build a raised garden bed.
Firstly, you have total control over the type of soil that your vegetables are growing in. This means that you won’t have to spend hours tilling the ground in your garden and adding amendments to the soil to make it suitable for growing your produce.
Raised garden beds are also great if you don’t have a large garden or you live in a unit with a small courtyard.
Some raised garden beds are also portable. So, if you’re a renter, you can easily take it with you when you move.
Lastly, raised garden beds are ideal for older gardeners or those with mobility issues because you can raise the bed to waist height which eliminates the need to bend down. This makes looking after your garden so much easier.
Types of raised garden beds
Raised garden beds come in all shapes and sizes. You can build one from scratch using recycled timber, sleepers, corrugated iron, bricks, or even Besser blocks.
In addition, there are numerous kits available made from a variety of different materials. These can be made from plastic, metal, or timber. I’ve even seen large wooden crates for sale like the ones you see at produce stores that are ideal for use as a raised garden bed.
Then, there are some very sophisticated kits available that include their own irrigation system, wicking beds, and even covers to keep the insects at bay.
While these can cost more, they can be a great way to start your own veggie garden if you’re not too handy with the tools.
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How to build a raised garden bed
The easiest way to build your own garden bed is to use recycled timber.
You want to ensure that the timber has not been treated with CCA as the nasty chemicals used for this can leach into the soil. CCA stands for copper and chrome arsenate.
Here’s a simple guide to building a raised bed that is 2.5 metres long and 1.25 metres wide, adapted from this guide by Gardening Australia.
Materials needed:
- 4 sturdy timber posts that are 70 cm high
- 2 solid timber planks that measure 20 cm x 5 cm x 1.25 metres for the short sides
- 2 solid timber planks that measure 20 cm x 5 cm x 2.5 metres for the longer sides
- Landscaping fabric to line your bed if you want to use it
- Screws for securing the timber and tacks for securing the landscaping fabric
Tools needed:
- A drill for predrilling the holes for the screws
- A screwdriver for securing the screws
- Large clamp for holding the timber planks to the posts while securing them
- A spade or other digging tool to dig the holes for the posts
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Instructions for building the raised garden bed:
Prepare the area by removing weeds and grass. Remember to choose a sunny spot for your veggie garden.
Sink the posts, around 10 cm deep into the ground. You don’t have to concrete them in because the soil will hold them in place.
Start on one corner and attach one of the shorter planks to the post with screws. You should predrill the holes to make it easier and use the clamp to hold the plank in place to make sure that it gets secured nice and tight.
Secure this plank to the post on the other end and then add the second plank on top of the first one to create the height and secure it.
Do the same with the other short side by securing the planks to the posts.
Next, you want to add the planks for the long sides. Start with one side and secure the lower plank and then add the second plank above it. Repeat this with the second long side.
Your raised garden bed is now complete and you can start to fill it.
The best wood for a raised garden bed
One of the best timbers that you can use to build a raised garden bed is recycled hardwood. This includes sleepers.
You can also use treated pine but make sure that it is H4 treated and ideally not treated with CCA.
While CSIRO has saidthat the risk from using CCA treated timber for vegetable gardens is within tolerable limits, for growing vegetables, many people prefer to not use treated timber.
H4 treatment can be conducted using a non-arsenic-based preservative that is termite resistant and suitable for outdoor use. Bunnings have a range called H4 Treated Pine Sienna MicroPro that could be a good option.
Should you line your raised garden bed?
In Australia, it’s not an absolute necessity to line your raised garden bed since we don’t have digging garden pests such as moles and gophers.
However, there are a couple of reasons why you might want to. Firstly, if the ground that you’re placing the garden bed on was heavily infested with weeds, lining it will provide a good barrier.
Secondly, it will stop the soil from moving out of the bed as you constantly water it.
Finally, if you’re placing your raised bed onto concrete or another hard surface, you definitely want to line it to stop the soil from staining the surface below.
To line your raised garden bed, only use good-quality landscape fabric, geotextile fabric, or weed matting that will allow water to flow through freely.
Never use plastic as this will retain the water at the root level and you’ll end up with root rot problems.
How to fill your raised garden bed
Filling your raised garden bed is easy when you use the layering method.
Here’s what you need to do.
Materials for filling the raised bed:
- A few bags of animal manure
- Compost, either from your own compost bin or in bags that you can purchase from your local garden centre
- Some garden soil, either from your own garden or from the local garden centre
- A bag of straw or sugar cane mulch
Instructions for filling the raised garden bed:
To cut down the cost if you’re buying compost for your raised bed, fill the bottom half of the bed with garden soil.
Use the landscape fabric to line the base and the sides of the bed. Use tacks to hold this in place. This effectively creates a barrier for the roots of the plants but will still allow the water to drain through. This part of the process is optional, however.
Next, you want to layer the remainder of the bed with animal manure and compost. Start with a layer of animal manure and then add a layer of compost.
Add some more manure and another layer of compost and top the bed with a layer of straw or sugar cane mulch.
Other tips for starting a raised garden
Once you have your raised garden bed all set up, you should consider installing some type of irrigation system so that you don’t have to hand water on a daily basis.
Raised garden beds have excellent drainage, so on hot summer days, your bed will require more water than if you were growing in the ground.
However, if you use a drip irrigation system and connect this to a timer on your tap, this task is made much easier.
Another thing to remember is that the soil and compost will need replenishing from time to time, especially if you don’t use a liner.
This is actually a good thing because you can add compost to your bed in between plantings and replenish the nutrients at the same time.
FAQ
What do you put in the bottom of a raised garden bed?
If you’re raised garden bed is placed on soil, place a few layers of newspaper and cardboard in the bottom to suppress the weeds. You can also line your bed with good-quality weed matting or geotextile fabric that will allow water to drain freely.
How deep does a raised garden need to be?
The minimum depth of a raised garden bed should be at least 30 cm. However, if you build the bed a little higher, it will make it easier to tend the crops without having to bend down as much.
What are the disadvantages of raised garden beds?
The two main disadvantages of raised garden beds are that they’re more expensive to set up in the beginning and that they will require more frequent watering as the drainage is so good. However, if you install an irrigation system and have this on a timer, it won’t take up a lot of your time.
Insights, advice, suggestions, feedback and comments from experts
Raised garden beds are a popular choice for many gardeners due to their numerous benefits. They make tending to crops easier by eliminating the need for bending down or heavy digging. In addition, raised garden beds provide better control over the type of soil used for growing vegetables, making it unnecessary to spend hours tilling the ground and adding amendments [[1]].
One of the main advantages of raised garden beds is that they are suitable for small spaces, such as small courtyards or units, where traditional gardens may not be feasible [[1]]. They are also portable, making them a great option for renters who can easily take them along when they move [[1]].
Raised garden beds are particularly beneficial for older gardeners or those with mobility issues. By raising the bed to waist height, they eliminate the need to bend down, making it easier to tend to the garden [[1]].
There are various types of raised garden beds available. They can be built from scratch using materials like recycled timber, sleepers, corrugated iron, bricks, or Besser blocks. Alternatively, there are kits made from plastic, metal, or timber that are easy to assemble. Some kits even come with additional features like irrigation systems, wicking beds, and covers to protect against insects [[1]].
When building a raised garden bed, using recycled hardwood or sleepers is considered one of the best options. Treated pine can also be used, but it is important to ensure it is H4 treated and not treated with CCA (copper and chrome arsenate) [[1]].
Lining a raised garden bed is not necessary in Australia, as there are no digging garden pests like moles or gophers. However, lining the bed can serve as a barrier against weeds and prevent soil from moving out of the bed when watering. Good-quality landscape fabric, geotextile fabric, or weed matting can be used for lining, while plastic should be avoided as it can cause root rot [[1]].
Filling a raised garden bed can be done using the layering method. Start with a layer of animal manure, followed by a layer of compost. Repeat this process until the bed is filled, and top it off with a layer of straw or sugar cane mulch. This layering method helps provide nutrients to the plants and improves soil quality [[1]].
Some additional tips for starting a raised garden bed include installing an irrigation system to make watering easier, as raised garden beds have excellent drainage. It is also important to replenish the soil and compost from time to time, especially if a liner is not used, as this helps maintain nutrient levels in the bed [[1]].
In summary, raised garden beds offer numerous advantages, including easier crop maintenance, better control over soil quality, suitability for small spaces, and accessibility for older gardeners or those with mobility issues. They can be built from various materials or purchased as kits, and filling them using the layering method helps provide nutrients to the plants. Lining the bed is optional but can be beneficial in certain situations. Installing an irrigation system and replenishing the soil and compost are also important considerations for successful raised garden bed gardening [[1]].
