Raised bed options

[GreyCat]

Well, my polytunnels are up and running on a mix of a couple of small raised beds, growbags and various buckets/pots etc, but i am starting to plan for doing the main raised beds properly after the tomatoes etc have finished.

But I'd like to garner some thoughts on my options from the forum hive mind.

Background: the raised beds must be minimum 200 mm (8 inches) or so deep because the ground underneath is a mix of gravel, rocks and some small amount of soil. I knew I would need raised beds when I put the tunnels there, however tunnels are located where they are as it's (a) level-ish, (b) the light is as good as it gets, (c) it's sheltered a bit, (d) the rest of the surrounding area is a swamp and (e) the only other location would have needed planning permission as extends forward of the house.

I am not paying silly money for delivery, as I have a truck which takes a bunch of 1.8m lengths (it is 2.3m long load bed and although I can get a small number of 2.4m lenghts in, not that many) and can carry half a tonne, in any case prefer to shop locally.

I have whittled down the options:

(1) Rough sawn treated timber. 150mm x 25mm by 1.8m lengths. Would need building 2 high and bracing. Local supplier about 25 min drive away. Cheapest option and quickly available. Treated softwood timber, would need to cut to size and quite a bit of build time.

(2) Softwood sleepers, 195 x 95 x 1.8 (and 1.2 and 0.6) lengths, can select so I don't need to do any cutting to size. Same local supplier as above, would fit all I need in my truck. About twice the price and heavier to work with. Single layer needed- less work.

(3) Milled wood from a local sawmill, sourced locally. 200mm x 50mm x 1.8 or 1.2 (some cutting required) or 200mm x 38mm (same lengths). Single layer needed- less work. Choice of Western Red Cedar, Larch or Douglas Fir. The Cedar or Douglas Fir seem options that resist rot naturally. 10 to 20 working day lead time (not a problem). Western Red Cedar is most expensive, the Douglas Fir comes in lower price than the sleepers option. Not many reviews of the mill on google and they are a bit mixed. Mill is about 40 minutes drive away and all would go in my truck.

So, I am a bit torn. My heart is saying the Douglas Fir or Cedar from the sawmill, my head says the sleepers are a more reliable option.

Aside from the potential issues with customer service at the mill (I will do the acid test and phone them and see how they respond), I like the approach of local source timber which does not need treatment. Local source: there's a bunch of old Forestry Commission plantations in the area, now being selectively felled and native trees planted in felled areas.

But the sleepers will be bombproof.

This is a significant project- it is 10 beds each 1.8m x 0.6m. There's a couple or three of months before I would be starting, so I have time to ponder, wait for materials and generally get it right. This is to be a "fit and forget" approach, and I plan to source good quality organic compost (to add to my own) to fill the beds. Budget is not unlimited- but I would rather pay a bit more and do it right once, than need to redo in a couple of years time.

What does the hive mind think? What would you do?

GC

 

[Toddy]

I think it depends on how tidy you want it to be.

I know a couple who lived on fresh air, wombling and the kind of happychance of swapping good labour for 'stuff'.

They sourced the sawmill scraps...the outside bark strips that gets taken off to get to the useable timber.
They literally used those to frame what we would now call hugelkultur but in the past in the UK we called lazy beds.

The crucial bit was siting the beds. Never mind the subsoil, where are they in relation to light and water and wind.

The thing was though, those outside bark rich 'planks' don't last terribly well, and certainly not when in contact with soil, but they last long enough to get a couple of years, and then my friends just broke them up into the bed and lined it with new ones.

Cost them nothing but a bit of labour, and the end result is incredibly productive beds of rich black soil.

Not so much built in obsolescence as an acceptance that they used what they could find, did the work and as the seasons turned they just kept it going.

Lazy beds aren't, but they produced really good crops in very small areas. Carefully sited, every kind of organic material they could find added to it. The midden, the old thatch, the ashes....it's all in it's way nutritious to the soil.

My eldest son and his girlfriend bought a house last year. It's on heavy Lanarkshire clay soil, but it has a little orchard, and it has raised beds.....which originally were filled to the top with good topsoil. Cost a fortune to do apparently....but the soil slowly sinks, slowly becomes impoverished, and the sides of the beds need work too, the move, they rot, they collapse. They're working at it; they're composting everything, even the bedding from the duck house. They could just have bought another lorry load of topsoil, but they both know soil needs work, especially trapped in a raised bed, especially if you're taking crops from it.

Very few allotments have raised beds, they just carefully work the ground, keep it fed.
I don't know anyone who has raised beds who hasn't had to add to them at times, but I can show old lazy beds going back over a thousand years that when re-opened and worked over, still produce good crops on what is otherwise really harsh land. Pockets of Fertile Soil....just carefully sited.

You're good at planning, good at the work, I'm sure whatever you decide will be successful, just I don't think the work is ever a one off and it's done and dusted.
Very best of luck with it

M

 

[Pattree]

Will your truck haul pallets?
Do you have a supply of pallets?
My homesteading friend used halfed pallets held up with angle iron in some places and rough sawn timber in others.

Yes they rot but you get a few years and they don’t all go at once.

 

[TeeDee]

Timber and corrugated sheeting cut down can make a strong high raised bed.
I would advocate for going higher in height because if you put the effort in now , you'll be paid back when you are a tad older. Its in investment in time and energy for a latter pay off - also lets you put some manure in the bottom for a longer enrichment of the soil.

 

[slowworm]

Personally, for growing food in I've never liked the idea of treated timber or something you don't know what's been done to it such as pallets.

I've just got one raised bed and I used locally milled larch. It's lasted about 10 years untreated but is fairly rotten now. The local mill was ok but took a lot of chasing as I'd asked for some wide larch planks and a fair bit of WRC which the mill took a while to source. In the end the WRC wasn't great quality as it has a few soft knots in it, fine for my use of making hives but not ideal for raised beds. So, if you get boards milled locally it might be worth ensuring the quality of the logs is up to the job.

I would question how long modern treated timber will last as you hear people moan about it.

 

[Falstaff]

There's one of the commercial raised beds growers on Youtube who got rid of his sides and just lets it taper off. He found it stops the slugs having somewhere to hide and didn't affect productive area.
I'm half and half, I lift my treated planks out for the winter and loose fit them back with stakes for the summer. I also pour a cheap kitchen saltwater mix along the bottom edge of the boards into the ground to kill & deter sheltering slugs hiding under the edge - seems to work.

 

[Mesquite]

Scaffold boards might be a good option for you and a lot sturdier than 1" boards. Used ones work out a lot cheaper than new timber

 

[Broch]

Our garden is on sloping ground so I had to build terraces. The first lot I did used second hand scaffold boards but they rotted down far too fast. The second lot I made from softwood sleepers. They're holding out much better 6 years on.

I had to build the lower wall three sleepers high on their edge. I joined them by boring half way through then used 250mm long heavy duty hex head self-drilling screws - I then plugged the holes. Half-round fence posts were driven into the ground against the wall and I used the same type of screw to secure to the wall. It has worked well so far!

 

[HorseGuy]

my head says the sleepers are a more reliable option.

the sleepers will be bombproof.

Due to my lack of knowledge I can't personally give any constructive advice on what wood would work best as I have no idea. But reading through your post you seem to have already answered you own question:

You heart may 'want' one of the other options but logically you seem to have already come to the conclusion that the sleepers would be the most sensible and functional choice.

So ask yourself what is the most important factor for you. Something which will look pretty or something which will be reliable and long lasting?

 

[GreyCat]

Many thanks everyone for your replies. Much food for thought, and indeed @TeeDee's suggestion has reminded me I have a pile of corrugated metal sheets in a pile in a corner (salvaged during the renovation.

@HorseGuy : yeah the sleepers do seem the logical choice, not least because I can add a layer later on if needed later on.

There's some composite scaffold boards near me on a well known auction site at the moment, but not sure if they have the amount I would need. And plastic doesn't appeal somehow.

I am not too worried about slugs as the beds will be in the polytunnel on a ground of gravel (hence specific size needed), and so far with the various things I have growing in a mix of old pots, buckets and grow-bags, not been much evidence of slugs...... so far.

There's a place down the road I found does pallets- will visit them, but I see used pallet collars are going for silly money on eBay now folks have realise they are useful for raised beds. However for general use beds outside, pallet collars would be way to go as being cheap and cheerful.

GC

 

[bobnewboy]

In our raised beds I used gravel boards, as they are available in bulk numbers, are well treated for contact with soil, and are of dimensions that are exactly what I (and you) were looking for. I did give them an extra coat of Cuprinol Ducksback wood finish before assembly. They’ve been down in our fruit cage for 7 years now, and seem to be holding up.

 

[TeeDee]

Wickes H Shaped Slotted Timber Fence Post - 90 x 90 x 2400mm | Wickes.co.uk

Wickes H Shaped Slotted Timber Fence Post - 90 x 90 x 2400mm

www.wickes.co.uk

These can be reasonably useful as vertical uprights - @ £22 for 2400 , divide that by whatever figure you need to stick out of the ground and be concreted in.
Slide a piece of corrugated roofing material down the recess from above and fix in directly with screws into the wood and then with a piece of appropriate sized batten screwed in to keep it all snug and tight.

 

[Falstaff]

Pallets rot pretty fast. so do most untreated scaffold boards.
One thing you can do for any left-in wood, incl planters, is to (galv) staple DPMembrane or cut open rubble bin liners on the inside and around the bottom edge. Almost any timber lasts a lot longer like that.

 

[dnarcher]

Use 2400X50 X200 C24 as your main boards, if delivered you can get them 4.8m long. If you want to build them 2 deep, use 50mm square c24 for the corners and screw in from both side boards. I used the screwfix 80mm t25 screws, predilled 2.5mm holes. Line the wood with dpm before the soil goes in. Spray the outside with ronseal fence treatment. I built 5 beds, two planks (400mm) high, 2.4 by 1.2m.
Halved one to make an acid bed.
I bought a rage sliding chop saw, which made the job a lot easier, and i highly recomend some kind of electric screwdriver. Mine are 6 years old now, and still in excellent condition. Oh, and thats a lot of wheelbarrows of soil, compost, manure and grit by the way.

 

[Mandelised]

I have used scafold planks, when these rotted i used sleepers and now those have rotted, so i went on a bricklaying one day course and will be building brick raised beds. My dad always used pallet collars on his allotment. https://www.universalpallets.com/product/brand-new-standard-size-pallet-collars-heat-treated-copy/ Super cheap esp 2nd hand on the right industrial estate. and instant.

 

[slaine_23]

(2) Softwood sleepers

I heard or read somewhere that sleepers are a bad idea if talking about using the treated ones for food? Old scaffolding is a good choice apparently because they have lifespan as scaffolding but are still more than good enough for these sorts of jobs. The raised beds I just got rid of (more than 15 yrs old) were just treated timber.

 

[Mandelised]

I heard or read somewhere that sleepers are a bad idea if talking about using the treated ones for food? Old scaffolding is a good choice apparently because they have lifespan as scaffolding but are still more than good enough for these sorts of jobs. The raised beds I just got rid of (more than 15 yrs old) were just treated timber.

possibly from the old days when the railways treated them with less friendly preservatives (creosote ) they used to literally soak them in it.

 

[HorseGuy]

I have used scafold planks, when these rotted i used sleepers and now those have rotted, so i went on a bricklaying one day course and will be building brick raised beds. My dad always used pallet collars on his allotment. https://www.universalpallets.com/product/brand-new-standard-size-pallet-collars-heat-treated-copy/ Super cheap esp 2nd hand on the right industrial estate. and instant.

I'm no expert but if I were to build raised beds I would go for a proper brick one with good drainage.

 

[Pattree]

I'm no expert but if I were to build raised beds I would go for a proper brick one with good drainage.

I’ve done that for the decorative part my garden but in my opinion brick would take up far too much space in a polytunnel. I would want a double course. In any case, even with a 4 1/2” brick wall there is no flexibility as there is with wooden beds.

I’d certainly go for something 600mm high rather than 200. So much easier to manage.

 

[slowworm]

I'm no expert but if I were to build raised beds I would go for a proper brick one with good drainage.

I'm considering some sort of hybrid deep bed/cold frame and thinking of brick or whitewashed block. With a cover of some sort It would give us a deep, rich bed and some protection to raise crops earlier and save room in the greenhouse.

I would agree that brick might be a bit of overkill in a poly tunnel.