There was quite a bit to building my raised beds so I am splitting it into two posts so as not to bore you (or to bore you twice, depending on your point of view).
In a previous post I rambled on about my decision making process on what to build the raised beds from. Now I had to decide how to construct them. I know my way around a cordless drill and a saw, but I am no DIY guru, and I had to deal with a sloping site. So I set about exploring the Google tubes for some simple plans…. and I found some excellent ones here. I won’t repeat the full instructions, but basically here’s what you do:
- Build a simple box frame where you want the bed
- Prop it up so that it’s level
- Hammer some corner posts in, and screw the frame to them
- Fill in the gaps underneath with timber that is cut to fit
- For long beds, brace the middle with metal bars to stop them bowing out when filled with heavy wet soil
I decided to plan the dimensions around the size of my sleepers (2.4 m long x 20 cm deep x 5 cm thick). This reduces the amount of cutting you need to do. Also, a 1.2 m wide bed – half a sleeper – was pretty much exactly what I wanted anyway.
Next I used Visio to draw up a scale diagram so that I’d know it was all going to fit, and exactly how much timber to buy. I wanted a long bed down the whole 10 m southern fence line of the back garden, which faces north and is in full sun for most of the day. This is to grow espaliered fruit trees in. I have read that espaliered (dwarf) fruit trees should be spaced about 2 m apart, which meant I could fit in 5 trees along the fence line. I decided to squeeze in one more tree by making the bed into an L shape, with a short 2 m section as the bottom of the L.
The fall of the ground along this fence line is around 60 cm, with the higher end at the back, so I had to cater for that in the plan. I basically made a sort of terraced bed of 3 sections, each one dropping by the depth of a sleeper.
Espaliering requires solid posts, between which you run wires that the fruit trees are trained on. Since they have to support the weight of the (hopefully) fruit-laden branches, the posts and wires need to be strong. So I went for 3 m long, 10 cm cross-section posts, which I concreted into the ground every 2 m.
Apparently post holes for concrete should be 3 times the width of the post (30 cm) and at least 60 cm deep. Now, I didn’t fancy digging 7 of these in heavy clay soil by hand, so this presented an ideal opportunity to play with a big boys toy: a petrol-powered post hole digger. Apparently for 30 cm wide holes you need a 2-person machine, so I duly hired it and enlisted the help of J to bore the holes. Suffice to say lots of fun was had! And lots of hard manual work avoided. Here’s a picture of the beast – basically a giant motorised corkscrew:
And here’s what we did with it:
Next up was the construction of the frame, but that’s for the next post…