We have two types of raised beds: the larger ones are timber framed, but we also use some smaller metal raised beds in corrugated steel. They are more portable and can be used for specific crops; ideal for small gardens.

Size does matter for raised beds. It is important to be able to reach across them easily, so 1.2m is the maximum width you should use. Length can be adapted to your space. We have used 1.8m and 2.4m timber beds. Height is the most important factor. We tried 30cm, 45cm and 60cm high beds, and the optimal height seems to be 45cm. Ideally you would be able to rotate crops between your beds, and the 30cm beds are a little too shallow for good root crops. For our salad crops, we use a 60cm high table bed which makes it easier to protect those plants from slugs and ground flying insects.

All our timber beds come from Harrod Horticultural. A professional gardener recommended them to us and they have been an excellent investment. They are easy to build (I would recommend using an electric screwdriver) and very good quality. They also supply a very sturdy bed liner for these beds, which help prevent soil from leaching out at the bottom. Construction of the four timber raised beds took about 4 hours.

It is important to leave enough space between the beds to manoeuvre equipment, especially a wheelbarrow. There is a surprising amount of soil, compost, manure and other growing mediums that need to be moved between the beds, as well as all the organic debris at the end of the season.

Our metal raised beds are smaller, and can be configured in different sizes and shapes to suit your space. The corrugated metal is very practical and they have a cool vintage look about them. We use them for single crops that need to be contained, like strawberries and squashes. We use heavy duty weed membrane to line these beds. Their small size makes them easy to dismantle and move around if needed.

The last step is adding the growing medium. You need a lot more than you think. I use a combination of topsoil, compost and manure, and fill the beds 2/3 of the way up. That leaves space for a top dressing at the end of every season to replenish the soil. I top them up every year with fresh compost and manure.

The beds take about a week and ideally some rain to settle in properly. I had to top them up a couple of times with more soil to get it to the right height. Raking it over every couple of days helped to settle the soil.