This isn't to say what we did was the best way, or the only way but just how we did it! So if you're thinking of constructing a raised bed there may be a few tips in here for you.
First let's run through the advantages and disadvantages of raised bed gardening.
- You can choose the soil you add to a raised bed. So if your soil isn't optimal, no problem, change it out for some you like!
- They warm up quicker in spring, so you can get planting earlier.
- If you find it hard to bend or access the ground, a raised bed is easier to use - and they can be built fairly tall too.
- You can plant slightly more densely in a raised bed due to the earth not being quite so compacted.
- If your plot suffers with waterlogging or poor drainage, raised beds will provide a solution to that as they drain efficiently (as long as you don't fill them to the gunnels with clay soil.
- You don't have to dig over a raised bed as you do with a plot.
- Initial costs can be expensive - lumber/screws/brackets and soil all cost money (we were lucky in that this was all going free on our plot).
- Raised beds will need watering in dry weather where a plot may survive for longer without a watering.
- You must improve the soil every year (although you should be doing this on your plot anyway so it's not really a disadvantage).
So a few things to think about there. As previously mentioned we were lucky enough to be given the wood to create our bed, so this didn't cost anything. We purchased some brackets, I think these were around £7.
So the first thing to do is to decide where you want to place the bed. I decided that I want my bed to be for carrots every year. Strictly speaking you're supposed to practice crop rotation but I plan on removing and reviving my soil every year so this shouldn't be a problem with regards to pests.
Lay out the planks where you want them and when you're happy, butt them up against each other.
A good thing to bear in mind is that you don't want the middle of your bed inaccessible from either side - it wants to be big enough to be worth building it but not so big that you can't reach the middle without walking on it. You don't want to walk on your bed!
Here you can see that one plank is slightly higher than the other, so we dug a small trench to make sure the plank sat fairly level with the other one.
We started on the left hand side - we wanted to make sure there was enough space to walk alongside the bed (hence the paving slab).
Backfill the trench and shore some earth up against the side to hold it in place.
Place a bracket between the ends - you should only need two on each corner - one at the top and one on the bottom. Three is overkill and one in the middle isn't really enough.
Screw them in and when you're done you'll find they're surprisingly sturdy.
Do the same with the trench and plank on the other side.
When we got to the opposite ends we found that because our ground isn't level we needed to rest the bed on the paving slabs. This isn't an issue because we had planned for the slabs to run around the outside anyway.
Screw your brackets in place in all four corners as before and eventually you'll have the bottom layer of your bed.
We debated having two low raised beds rather than one tall one but I decided that because carrot fly tend not to fly more than 30cm high it would be more beneficial to have one tall bed (and at least you don't have to bend far to weed it).
So to construct the top level we just placed another plank on top of the existing one (with me balancing them as Adam bracketed them together) working our way around again, bracketing as we went.
We discussed placing stakes at each corner and screwing the planks to the stakes but because the planks are so heavy (old rafters we think) we didn't think we'd need the extra support.
Even though we decided we didn't want stakes, we didn't want the pressure of the soil when filled to knock the top planks away from the bottom. So we improvised to overcome and made some flat brackets out of our L shaped ones. To do this, you literally just lay it with the point up and whack it with the hammer. It's not what a professional would do but honestly we're on a budget here people (and couldn't be bothered going back to B&Q).
Screw the top planks to the bottom planks. You can see below the little v shape fits nicely between the planks as an added bonus.
We actually ran out of brackets for the end pieces and luckily one of our plot neighbours showed up and generously gave us some pipe clips (I think they were pipe clips) which served just as well to secure the top to the bottom.
So here you can see the completed bed! Nice and deep, ready for a spring planting of lovely carrots as soon as it's filled. There's a local company that will deliver top soil for £25 a tonne which is VERY reasonable, so we'll be taking advantage of that soon (there's no rush, we're not planting carrots until next year).
You can't see the paving slabs here but I placed them around the bed with gaps, I plan on planting herbs in the gaps to walk on - chamomile carpet smells lovely, makes lovely tea and actually enjoys being walked on. Thyme is also a good herb for this.
My next post will be about Autumn planting onion and garlic sets, mine arrived this week and it's about time for them to go in!