We are often asked for our advice on which soil to put into a raised bed, the best method of construction, whether or not to line them and a dozen other queries. Therefore we thought that a post covering the reasons why you might want to use them, and the best methods of doing so, might be helpful.

The first recorded mention of raised bed gardening was amongst the tribes of Bolivia and Ecuador, in around 300bc. They used a method called “waru waru”, which involved raised fields, built alongside canals to provide irrigation. Similar techniques were then used by the Aztecs and Mayans, and have continued to be popular throughout history.

Raised beds are now taken to mean a timber or plastic box filled with soil, but any method of raising the soil level from the surrounding area has the same effect. 

Benefits

You can control the soil type within the bed

In my mind this is far and away the biggest benefit of raised bed gardening. By controlling what goes into the bed you can do away with a lot of the challenges that gardeners face.

Want to grow both acidic and alkaline loving plants in the same garden? No problem, simply add lime for a more alkaline soil, or coffee grounds, pine needles or sulphur for a more acidic soil. 

Want competition winning carrots? By sifting the soil as it is added to the bed you can ensure that there are no nasty stones lurking beneath the surface, just waiting to make your veg fork out in different directions.

Controlling the soil that is within the beds also means that it is less crucial what the natural soil of your garden is, although gardens with poor draining soil may still have to take some steps to overcome this.

Raised beds are easier to work in

Although this is typically phrased as an advantage purely for older gardeners, the reduced stress on your back and knees should be taken into account for people of all ages and levels of fitness.

Gardening tends to mean spending lots of time bent over, in contact with the ground, whether this is when planting, weeding or harvesting crops. Having that ground 300-600mm closer to you can make a big difference to the level of stress on your back, knees and hips.

Better Drainage

Although they aren’t a magic cure for poor drainage, a raised bed will certainly help in areas with drainage issues.

Provided they are filled with the right soil type then a raised bed will drain rainfall away up to 20% faster than a ground level bed. There is a downside to this however, they will require more watering during hot, dry spells.

No till gardening made easy!

No till is something of a buzzword in gardening at the moment, although there is still a debate as to whether or not it is the best way forward. Simply put, no till gardening does away with the traditional method of digging a bed over each season to add organic matter and instead replaces nutrients by adding compost or other well rotted organic matter to the top of the bed and letting worms and other lifeforms distribute them throughout the soil for you.

A key element in no till gardening is reducing unnecessary compaction of the soil, and a well sized raised bed helps as you can reach the middle from both sides, meaning that there is no need to walk on your soil. 

If you are interested in learning more about no till gardening there is a great article at growveg.co.uk.

Layout and aesthetics

For people that like a well laid out garden, raised beds are a great option. They will typically all be the same size, with straight edges and well defined pathways between them.

This not only helps with the look of the garden, it also makes upkeep easier, as there are clear zones to work on.

You can plant in them earlier in the season, and get longer growing times

Due to the improved drainage, increased organic matter content and better solar conductivity plants can be propagated into raised beds earlier in the season than would be the case in traditional beds.

This also holds true at the end of the growing season, where many gardeners find that they get a few extra weeks of growth on plants in a raised bed, or can even overwinter some varieties that they haven’t been able to previously.

Pest Control

Although slugs can climb a raised bed can provide the opportunity to slow them down, or defeat them entirely. There are dozens of different slug defense products, from copper tape to lambswool, some of which are more effective than others. Whichever method you choose, the sides of a bed give a great opportunity to position the defences away from your crops and stop more slugs.

The walls of a bed are also great for fixing cages or netting, which can be key to stopping birds or deer from eating what's inside.

 

Constructing and filling beds

Size

The right size for the beds will depend on the size of your garden, what you want to grow in them and your budget. However there are a few things to consider when planning.

Firstly, consider how much space you want between each bed. At a minimum you will want to be able to walk between them easily. If you want to be able to get a wheelbarrow between them for easy addition of compost then you will need a wider gap. We normally recommend a 1- 1.2m gap in this case.

The next thing to consider is how wide you want them to be. If you have easy access from both sides then an external width of 1.2- 1.5m is ideal, as this enables planting anywhere in the bed without having to lean on the soil and compact it. For areas where you will only be able to access one side then you are better sticking to a width of around 600mm.

The final thing to consider is the height you want them. Again this will depend largely on what you want to grow and your budget, but as a rule of thumb the deeper the better. The more soil that is in the bed the more control you have. Any bed under 150mm deep will not get the majority of benefits of raised bed gardening as the roots of the plants will still be in the soil underneath.

Orientation 

The majority of gardeners will say that a north/south orientation is best for growing in, as it gives the most sunlight to the crops throughout the day. However if this doesn’t work in your garden, then don’t worry, lots of people are very successful with beds on an east/west orientation.

Soil Type

This is the question we are asked more than any other. Which soil is best for my raised bed? 

The answer is always the same, it depends what you would like to grow in there!

For general planting, or for people who haven’t quite decided what they are going to put in their beds, we would always recommend a topsoil/compost mix. This is a blend of our sandy loam topsoil, with added peat free compost to increase the nutrient levels. That means that it will be a great base no matter what you would like to plant.

If you are set on growing vegetables in your beds then the topsoil/manure mixture may be better for you. This is a blend of our sandy loam topsoil and well rotted manure. This is the perfect base for leafy greens and any heavy feeding vegetables, such as tomatoes, squashes, courgettes and cabbages. Root vegetables, such as carrots, parsnips and potatoes, will not need this mixture though, they will be better off with the soil/compost mix.

Soil Quantity

The second most popular question we get asked is how much soil will I need to fill my bed. Luckily this is very easy to work out, the formula is:

 

Length (In M) x Width (In M) x Depth (in M) = Cubic meterage of the bed

Once you have the cubic meters you can work out how many bags it will take to fill. Our bulk bags are always a minimum of 0.8 Cubic meters. Remember to add 10-15% for settlement of the soil once it is in the bed.

Hopefully this post has answered all of your questions, but if there is anything we have missed or you need some more help then please don't hesitate to contact us via email or on 01323 370265