How to make a raised bed: frequently asked questions

From how to make a raised bed to where to put it, we have covered the most frequently asked questions to help you make the best choices for your garden.

Q. What is the best position for a raised bed?

A. Once you have decided where you would like to build your raised bed, take some time to note where the sun rises and sets. The amount of light that falls on that particular spot will help you decide whether it is the best place to build it or not, for example, if your raised bed has shade cast over it for most of the day certain plants or edibles may not thrive there.

Q. What surface can a raised bed be built on?

Most raised beds can be built on any surface and there is no need for foundations or cement, build them directly on soil, grass, paving, tarmac, concrete or even sloped gardens, just make sure that you are building on a solid and level surface. WoodBlocX raised beds are unique in their design, incorporating a series of strong dowels which means they are able withstand ground movement when built on a reasonable surface. To find out how to build a WoodBlocX raised garden bed click here.

Q. What should I line my raised garden bed with?

A. We recommend using a geotextile membrane liner which should be placed in the bottom of the raised bed, as it will allow for better drainage. Use a damp proof membrane to line the sides of the raised bed and over the buttresses, this will ensure the structure remains in excellent condition.

Buy a liner for your raised bed

Q. What soil should I fill my raised bed with?

A. This totally depends on what you plan to grow. Raised beds are a great solution for gardens with poor soil as you can select the type you use. Filling the space with a rich compost mixture would work really well but would also be very expensive. We advise customers to use a good topsoil mix and add a soil improver or compost mix to the top layers. Sandy soil is the best all-rounder. Using a bought-in topsoil rather than using up any surplus from the garden gives you much more control over weeds. Soils can be made richer through using your own homemade compost or manure, but check whether these mixes are suitable for what you plan to grow and remember plants and vegetables can be supported with solid and liquid fertilisers too.

Q. What can I grow in a raised bed?

A. You can grow almost anything in a raised bed! Many of our customers favour them for growing edibles because the extra height makes the regular cycle of sowing, maintaining, weeding and harvesting really easy. Depending on the surface that your raised bed is built on you may need to consider planting deeper rooted varieties in taller beds rather than low-level beds.

Raised beds are ideal for organic growing as you can control exactly what is used in them, also ericaceous plants such as rhododendron and camellia can also be planted using an acidic soil mixture.

Q. How do I work out the soil quantity for my raised bed?

A. If you are filling your raised bed completely then a simple way to work out how many litres is length(m) x width(m) x height(cm). If you plan to add a drainage layer to the bottom, subtract the height of the layer from the equation.

Q. How do I maintain a raised bed?

A. Our raised beds are maintenance free, the wood is pre-drilled and then pressure treated, we expect them to last 15 years or more without rotting, cracking or warping. Our structures are joined by a series of dowels that help to create a rigid structure which can withstand tension forces (each dowel joint will withstand up to 0.9 tonnes of shear force in our tests).

Q. Can I build raised beds on a slope?

A. Yes! WoodBlocX raised beds are ideal for sloped gardens, the beds can be designed to match the contours of your garden and with the addition of ground spikes, which will help hold the structure down on slopes, helping to prevent the structure from slipping sideways down the hill. Ground spikes are placed on the first layer of all WoodBlocX structures and are also located in every buttress. Many of our customers also use WoodBlocX for retaining walls to landscape their gardens. We recommend using our Free Bespoke Design Service for these projects as our experienced team can help you work out exactly what you need.

Q. How deep does a raised bed need to be?

A. Raising the height of your garden beds and borders makes gardening instantly more accessible, but you also need to consider the layout of the rest of the garden. Paths and steps can prove troublesome, opt for wider paths if possible, especially between raised beds if you have more than one. Our wooden raised beds can be built at heights between 0.25m - 1.05m and each structure is strong and sturdy enough to sit or lean on. Our helpful calculator tools will help you to understand the best height to suit your needs, as you select the different height options you will see details of the different benefits that particular height offers.

Read our accessible gardening blog here.

Creating an accessible garden using raised beds

Q. How often should I water my raised bed?

A. This totally depends on there time of year but during warmer weather water twice a day, early morning and in the evening to prevent the sun scorching the plants. Solar or electric watering systems are a really good option if you struggle to lug watering cans around the garden. Raised beds also warm up quicker in the spring and cool down slower when the weather turns cold, which is brilliant for growing in general.

Q. Do raised beds need drainage?

A. Raised beds can be accessed without having to walk on them, this prevents soil compaction, which also improves drainage, helping plant roots to grow more freely and take on more nutrients. WoodBlocX raised beds of all sizes allow for drainage through the air gaps between each block, customers building our raised beds directly on patios, tarmac and concrete could benefit from a drainage layer at the bottom if the bed - stones or gravel can be used for this.

If your garden is particularly susceptible to collecting surface water and feel you need an additional drainage source you could add a French drain to the base of the wall, this requires you digging a small trench, adding a perforated drainage pipe, which will needs to be directed away from the wall to either a main drain or to somewhere where it can easily soak away. Then simply fill with Type 1 or subbase and cover.

Q. Can I build a raised bed on a roof or balcony?

Yes! WoodBlocX is perfectly suited to balconies and roof gardens thanks to the small light weight blocks which can be easily moved around, whereas lengths of timber and heavy railway sleepers can be difficult to get up stairways and into lifts. Our raised beds and planters can be made to fit tight or narrow spaces and will instantly add character to your outdoor space.

Find out about our free design service here.

Q. What weedkillers or fertilisers should I use when growing plants in a raised bed?

A. This is entirely up to the individual, we recommend using products that are kinder on the soil and environment, check for products that are clearly labelled natural, biological or have the stamp of approval from organic growing organisations such as the Soil Association or Organic Farmers & Growers Association. For weeds you can remove by hand or, if you're keen to use the no dig method, and have a space that you're starting from scratch with you can cover it with a sheet to stop the light getting in and then remove the weeds once they have perished. If you're keen to make your own natural weedkiller there's helpful information over at Garden Organic.

Q. What is the best wood for a raised bed?

A. Wood is by far the best material option for making raised beds, in most cases its easy to obtain, comes pre-treated and good value for money. The best wood for building raised beds depends on your preference. The most common varieties for for building raised beds, planters and even garden edging is pine or oak. Oak is generally much more expensive than pine. You can find out more about the different materials that can be used to build raised beds here.

Q. What is the best wood preserver for raised beds?

A. Buying a product that has pre-treated with a pressure treatment or wood that has been pre-treated is the best option. We drill the holes in our wooden blocks that our dowels fit into before we pressure treat the wood to ensure that the treatment penetrates almost 100% of the wood, this is why our structures will not rot, crack or warp. A pre-treated railway sleeper that is then drilled exposes untreated parts of the wood to moisture which, over time will lead to rot.

To browse our full range of wooden raised beds, ponds, planters, walls, seats and more or to find out about our FREE design service click below

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