Allotments 4 All

Hi

Well finally getting around to building the raised beds in the back garden. But need some sanity checking that i am doing this right.

Beds Themselves

2 beds are 4 ft wide and 16ft long
2 beds (against back fence) are 4ft wide and 6ft long with a 4ft gap between them.

Will be 4 scaffolding boards high.

Filling

On the existing soil i am going to put 2 layers of membrane.
Followed by newspaper and shredded paper
Followed by fresh straw which will have some perforated pipe though it and the pipe would be screwed up to each end of the beds at least a foot deep.
Followed by 2 layers of fleece completes wicking layer (will drill a overflow hole)
Back filled with compost mixed with Vermiculite
Top 6inches "fen black" soil

Hoping to resolve the issue with raised beds needing constant watering with a wicking layer and a soil that will hold some water.

Long term

I would like to make covers like these over the winter and spring as were in the fens i think it would help with wind damage.
Thinking over the summer i can swap the plastic for netting :)

http://www.motherearthnews.com/diy/garden-yard/raised-garden-bed-zm0z12fmzhun.aspx

Any comments welcome :)

Cam

I can't really advise much but I'll be interested to hear what others have to say!

Make sure there is air between the raised bed and the fence or it might rot.

Fresh straw tends to heat up, and then collapse as it rots.  6 inches of soil may be extremely expensive.  Do you have a source of recycled compost can be quite cheap.  Can you use some soil from the bottom and fill the hole with something cheaper.

Perhaps you can plumb in a drip to make watering easier.

I like the picture on the link.  Not sure how long scaffolding board last.  Suggest you think about using breeze blocks. 

yes have cheap supply of compost skip full for around £100

can't afford enough gravel for the beds would wood chips and straw work?

Hi Cambourne that's some project you have taken on, better you than be.

You asked for opinions so here is mine.

You seem not to considered a few things e.g. Weight of the soil, particularly when wet and the power of the wind.

I will comment on various things in your post in turn.

Quote1) Will be 4 scaffolding boards high.

You will need lots of intermediate posts  to support these,particularly on the 16 ft bed.

When the soil goes in the weight of the soil will tend to push outwards bulging the boards.

Personally in the long term I would have gone for two courses of 6" concrete blocks ( these won't rot)

You mention thinking of put what is basically a lightweight greenhouse on top of you boards.

In my opinion the boards won't support such a structure.

If you still want to use the scaffold board way  I would suggest you get metal hoops similar to those used in a poly tunnel.

These could be concreted in and the boards bolted them.

Then you could get some poly tunnel plastic and form a a roller blind arrangement with this.

This means you could roll it out in winter then roll it up in summer.

I mentioned wind power, a tunnel shape is more wind dynamic than that greenhouse seen in the link.

In terms of filling four boards is around three foot deep which will take a lot of filling two course of blocks will be only half that depth, and I think that is deep enough for most things unless you are going for long carrots and parsnips!

If you want to progress in stages then star with the two course of blocks and just cover the beds and use hoops made from 1" diameter water supply pipe and drape plastic over it in winter and or debris netting in summer.

Then later if you want to make your covers more permanent you could get metal hoops and bolt them to the blocks.


In terms of cost four rows of scaffold boards and wooden posts won't be cheap and the blocks might cost slightly more initially, but in the long term will probably work out cheaper because they do not rot and will contain the soil without bulging.

.....and that my thought on your project".....................well you did ask for comments :happy7:

In terms of moisture retention you could fix a seeping hose.