Building A Raised Bed
When we moved to our new house earlier this year our new front garden was completely slabbed over. The previous owners had used the space to park a works van and a car. It was functional but bleak and unlovely.
During the summer we started to soften up the edges of the garden by planting into the gravel at the edges, by the house and neighbour’s fence. We put in a climbing rose by the front door and planted alpines, hollyhocks and a row of Hyssop.
But we had always planned to dig up some of the slabs to create a large flowerbed, leaving about half of the slabs in place for visitors to park.
We started work on the front garden in late October and started taking up slabs, something that was reasonably easy to do. We took up 24 of them, breaking four in the process. We were also able to chip away at the layer of cement holding the slabs in place. But underneath this thin layer we found a much thicker and tougher layer of concrete, of unknown depth. It was time for a rethink.
We decided to make a raised bed where we had taken up the slabs, using old railway sleepers. The slab-free area was 16 feet by 6 feet and we decided to make the outside dimensions of the raised bed slightly larger, by resting the sleepers on the slabs. Luckily the front drive drains well, the concrete being porous and resting on very sandy soil, so we could leave the concrete layer in place. If not, we would have had to use a pneumatic drill to break up the concrete.
New sleepers cost about £35 – £40 each but we discovered that Ridgeons sell used sleepers for £15.46 each (+ VAT). Each sleeper measures 2.6m by 125mm x 250mm. These are reused railway sleepers, complete with holes where bolts had fixed the metal railway chairs to the sleeper. Reused sleepers are soaked in creosote, which is a potential carcinogen in contact with bare skin. However, it is still possible to use these sleepers provided you follow the regulations:
“Old railway sleepers treated with creosote can be used in parks, gardens, and outdoor recreational and leisure facilities but only if there is no risk of frequent skin contact. However, old railway sleepers treated with creosote must not be used inside buildings, whatever their purposes; in toys; in playgrounds and for garden furniture such as picnic tables.”
We used gloves when handling the sleepers and we found that they were relatively easy to cut and make into a raised bed two sleepers (500mm) high. We used nail plates to hold the sleepers together – right-angled plates for the corners and flat plates for horizontal joins. Nail plates cost between 55p and 84p each, depending on size and we used 14 small ones and two big ones.
We filled the bottom of the raised bed with some spare gravel for drainage and then a layer of partly-rotted turves, both left over from our work in the back garden. Then we ordered screened topsoil to fill the bed from local suppliers Longwater Gravel, who were cheaper than other companies we had looked at. We used their gravel calculator to work out how much soil we would need. We ordered four tonnes of soil, which was exactly the right amount.
The construction of the raised bed took us just over a day, spread over several days. The sleepers cost £185, the nail plates cost just under £5 and the soil cost £125. The weathered old sleepers look quite attractive and match the colour of the existing slabs.
The next bit was most fun – choosing and buying the plants. The front garden faces south and is very sunny, even in winter, so we had decided to use drought tolerant, sun loving plants. The two main features of the bed are a small olive tree which we grew in a pot for about ten years and a single Stipa gigantea ornamental grass. I first grew the Stipa in Grapes Hill Community Garden, where it puts on a magnificent display of airy, oat-like flowers from early Summer onwards. The grass reaches eight feet tall but the flower spikes are see-through, so plants further back in the bed will still make an impact.
Other plants for the bed included six lavenders, a couple of semi-hardy Salvia microphylla, several different varieties of Sedum (Sedum pachyclados, S. forsterianum ssp. elegans and S. forsterianum ssp. elegans “Silverstone”), Hebe “Emerald Gem”, Cistus × dansereaui “Decumbens” and some “Archer’s Gold” thyme. We also added some spare Erigeron karvinskianus plants from the allotment – a beautiful, spreading daisy that I first saw growing between cracks in paving in Hestercombe Gardens in Somerset – plus a few other smaller plants. For spring there are some miniature daffodils (Narcissus “February Gold”) and I’ll probably add a few dwarf irises as well. Since I’ve reused several plants we already had, the cost of plants has been around £70.
Already the front garden looks so much better. We’re looking forward to next year, when the plants should flower and start attracting wildlife.
Update – 29th November 2016:
We replaced the raised bed earlier this month – see my blog post “The Raised Bed Is Dead… Long Live The Raised Bed“.
Although this version of the raised bed only lasted for three years, it was well worth doing and could have lasted in its original form for many more years.
If I was doing it again, I would make a couple of improvements:
- Fasten a piece of plastic or rubber over the joins between sleepers, to prevent soil from washing out of the bed. This didn’t happen very much and plant roots help to prevent it but covering over the joins is very easy and quick and well worth doing. We did this when we rebuilt the bed, using small pieces of butyl rubber left over from building a pond.
- Buy better soil. The soil we used suited the plants in the bed but had become rather compacted. When we rebuilt the bed we bought topsoil mixed with soil conditioner (composted green waste). This was not much more expensive than the screened topsoil we used intiially.