Raised beds (now with pics)

[miles_hot]

In parallel with the fish tank build I will also be knocking together a set of raised beds. These will be around 2' tall and will be build using 2"x4" (approx) decking joists. I plan to wrap the inner surface in membrane to keep the soil away from the wood and hopefully prolong the life span of the "eco treated" softwood as I couldn't justify the outlay on oak. The top of each wall will then have an Oak sliver (maybe 2x1") of oak to hide the plastic. I plan to prefab each wall panel in the garage and then basically but joint each one to form the boxes of the raised beds in situ.

Currently I am trying to work out how to join the joists together to form each wall - something that is complicating matters is I am attempting to figure out how to enable each joist to be replaced separately when they actually start to rot out. This sort of rules out biscuit joints or just screwing each joist to the one below. The the moment it seems to be:
- Screwed to a strap on the outside of the bed
- Pocket screwed to the one below
- Bolted to a a strap inside the bed (would need to do something about the plastic when it comes time to replace

Any ideas?

Miles
PS Will post some pics of the design up when I have a little more time

 

[wizer]

On my old allotment I used 2x6 nailed together with a gas nailer (paslode). I copied a guys design on another plot. His had been there 10yrs. I reckon you've got at least 20yrs before it rots to the point you will have to replace it. If you're that worried then you could clad the front with shingles at a later date (I wouldn't).

How tall are these 'walls' going to be? The taller they are the more soil you're going to have to put in. If you're buying it, it becomes expensive (and back breaking).

Is this a veg plot or flowers?

This is all fresh in my mind as it's high on my to do list, now spring is threatening to break.

 

[matt]

How about wrapping each 2x4 individually and then screwing it to posts sunk in to the ground?

 

[jedmc571]

Could you simply butt join at the corners and countersink M6 / M8 Stainless coach screws and a washer? you can then remove it individually.

Straping would look untidy IMO, I used the above method about 10 years ago, the Tanalised timber was painted ( fence treatment ) and the coach screws uniformly fitted really stood out as a feature.

Cheers

Jed

http://www.screwfix.com/prods/13503/Bol ... Pack-of-10

http://www.screwfix.com/prods/54830/Bol ... Pack-of-10

 

[frugal]

I am currently doing something similar in the garden. 2' tall seems very high. I am making 6 beds, each 10'x4' and 8" high. I am working on the theory that the wood will take long enough to rot that we will have rearranged the garden by the time it gets bad enough to replace.

I am not bothering to use plastic sheeting as the compost heaps have survived well enough for 10 years

I am using 2" posts 2' long in each corner and along the sides, then just screwing planks to the posts. The whole lot then gets a coat of presetvative before being back filled with soil and compost.

I am sure that I could have just used the posts at 8" long and rested the whole thing on the ground, but I wanted to ensure that the sides did not bow out. So it ia all anchored 16" into the ground.

My first attempt was to make it all up in the workshop first and then just hammer it all into place. That caused the planks to split as it was driven in unevenly. Now I put the corner posts in first and get them all the right height (the ground is sloping and uneven so there has been a significant amounbt of digging out). Then I put the top planks on all around and then once I am happy that everything is straight I put on the bottom row of planks.

 

[miles_hot]

On my old allotment I used 2x6 nailed together with a gas nailer (paslode). I copied a guys design on another plot. His had been there 10yrs. I reckon you've got at least 20yrs before it rots to the point you will have to replace it. If you're that worried then you could clad the front with shingles at a later date (I wouldn't).

How tall are these 'walls' going to be? The taller they are the more soil you're going to have to put in. If you're buying it, it becomes expensive (and back breaking).

Is this a veg plot or flowers?

This is all fresh in my mind as it's high on my to do list, now spring is threatening to break.

The walls will be 2' tall - that is a lot of soil however I have two siazable piles from when we had the extension done to get rid of in the lawn as it stands so the hight is a useful thing. It will also reduce the amount of bending / kneeling which will be a blessing.

The plot will be mainly veg with some flowers - we will be adapting the "square foot garden" method so that will be interesting.

The breaking of spring is also in mind - I've just ordered the 19 odd metres of 2x4 which will be needed (though that figure feels alittle low in some respects - maybe the project is just looming large in my mind?!)

When you talk about the wood in the allotment staying there for 20 years I assume that it was softwood in contact with the ground? I ask as fence posts seem to rot rather faster than that

Miles

 

[miles_hot]

How about wrapping each 2x4 individually and then screwing it to posts sunk in to the ground?

Unless the post is on the outside I can't see that this would help - and if the post is on the outside it seems to me that having the poly spanning the gap of the plank that has just been removed would help the whole process.

Thinking about it if I have the post on the outside I would be unable to remove an individual plank without removing the post.

If the post is on the inside screwing to it will puncture the membrane limiting it's usefulness in waterproofing the timber. Rats, I think the post idea doesn't work with the membrane idea! Mind you from what others have been saying I may not need the membrane...

Miles

 

[frugal]

You haven't said how long or wide this bed is going to be. even with 2" thick walls, a 2' high bed is a lot of weight to retain without the sides bowing.

Admittedly I am only using 3/4" think planks rather than 2", but even with 8" high walls I need a support post every 2' or so to stop it bowing out.

 

[miles_hot]

Could you simply butt join at the corners and countersink M6 / M8 Stainless coach screws and a washer? you can then remove it individually.

Straping would look untidy IMO, I used the above method about 10 years ago, the Tanalised timber was painted ( fence treatment ) and the coach screws uniformly fitted really stood out as a feature.
Cheers
Jed

I'm not sure I understand - don't coach screws have to have a nut? In which case where are your screws put and in what orientation?

many thanks

Miles

 

[miles_hot]

You haven't said how long or wide this bed is going to be. even with 2" thick walls, a 2' high bed is a lot of weight to retain without the sides bowing.

Admittedly I am only using 3/4" think planks rather than 2", but even with 8" high walls I need a support post every 2' or so to stop it bowing out.

The beds will be 4' and 2' wide, I can't remember the lenghts (as promised I'll post some pictures tonight) but between the thee beds I think I have around 90 square feet, so something like 2x12, 9x4 and 8x4 feet??

I wasn't expecting to have to stake the centres of the walls - partly because when you mount up soil it takes around a 45* slope so that implies that only a triangle 2'x2' will need to be supported and I figured a 2" wall would be able to do this. I am of course all ears if this is not thought to be the case.

In terms of staking to the ground I was again not expecting to do this (thought my original design did have this) as the box would be heavy enough not to move and would be pretty ridged as a structure. ... again all ears if this is being silly!

Miles

 

[BMac]

I use scaffold planks to build raised beds. The beds are 8'x4'x9" and I use a kneeler to work at them. I put 3"x3"x12" posts in the corners and one in the middle of each long side and just dig a little hole for each to hold the bed in position.

It takes a huge amount of material to fill a bed (three beds take about 2 cubic metres) so you are going to get plenty of shovelling practice with 2' high walls. You will need to reinforce the walls because, as the soil compacts, it will push them out. I would suggest getting a few big bags of perlite and mixing that it to ease the load a bit as well as giving good soil structure.

I don't use a preservative because the beds will last for ages and cost me nothing because I get the planks from a mate who runs a plastering firm and is dumping planks that would fail H&S all the time.

Brendan

 

[wizer]

The plot that I mentioned in my initial post used standard sawn 2x4s from a builders yard and was just sitting on the soil and he'd not treated it any further, no inner liner and he said it'd been there 10yrs. It looked in good nick, so I see no reason why it wouldn't have gone longer.

I think you need to think about how long you're going to want these beds in their current position. 2' high is fine but I wouldn't fill it to the top. Leave plenty of room for mulching. The benefit of raised beds is that the soild doesn't become compacted and, with continued mulching will be fab for veg.

I wouldn't recommend the square foot method. Too formulaic and very American. Just follow the cottage garden method (forget the book\tv series).

 

[Dan-K]

I've just ordered the 19 odd metres of 2x4....

Did you miss a zero off there? Because with 2' walls and your 3 beds...well I worked it out to be in the region of 140 metres required (468 feet).

Have you considered using sleepers? They make excellent raised beds, won't need posts to hold them up, and won't bow...and second hand ones are heavily preserved so last forever.... plus, they're usually oak. And they're not so expensive considering what you get for the price.

 

[miles_hot]

I've just ordered the 19 odd metres of 2x4....

Did you miss a zero off there? Because with 2' walls and your 3 beds...well I worked it out to be in the region of 140 metres required (468 feet).

Have you considered using sleepers? They make excellent raised beds, won't need posts to hold them up, and won't bow...and second hand ones are heavily preserved so last forever.... plus, they're usually oak. And they're not so expensive considering what you get for the price.

Ah... good spot I'e actually ordered 260m

Miles

 

[miles_hot]

And now the pictures. I have shown the garden with the "square foot garden" grid as that's this week's book. Tom - do you have any further clues on your suggested approach as there's a lot of books out there with the sort of title! I agree that his approach is both very formulaic and rather boastful - i.e. I invented it all and "if it doesn't have a grid it's not a SFG"! . It does however seem to have some good points in it so we'll be heavily borrowing from it



All in all looks like a lot of work

Miles

 

[BMac]

Miles, my two reference books are 'The Vegetable Expert' by Dr. D.G. Hessayon and a new publication by Gardeners' World called 'Grow Your Own'. I find myself leaning towards the GW publication more and more.

Brendan

(There is a 'Grow Your Own' (very good) magazine too, not to be confused with the GW title)

 

[miles_hot]

Miles, my two reference books are 'The Vegetable Expert' by Dr. D.G. Hessayon and a new publication by Gardeners' World called 'Grow Your Own'. I find myself leaning towards the GW publication more and more.

Brendan

(There is a 'Grow Your Own' (very good) magazine too, not to be confused with the GW title)

Do these contain references to the differences that the raised bed approach can bring - as I understand it stuff can be grown closer together (overall) than would be normal in a veg patch such as my dad uses where you have to be able to get between the rows?

Miles

 

[jedmc571]

Miles,

Coach screws are just a bigger version of a normal screw, you're confusing it with a coach bolt.

They are fitted through pre drilled holes through the end face of one timber into the end grain of the other, easily allowing you to remove if required, but considering Tanalised timber has a life exppectancy of 20 years above ground and 10 - 15 years with ground contact, I think you might be over thinking this one.

Cheers

Jed

 

[wizer]

Miles it was the guy who used to present Gardener's World before Titchmarsh. Geoff something I think. I'll go through my collection later and dig it out.

 

[miles_hot]

Miles it was the guy who used to present Gardener's World before Titchmarsh. Geoff something I think. I'll go through my collection later and dig it out.

Thanks Tom

Miles