Raised Beds - Soft or hard wood?

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melliff
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I want to install some raised beds in my garden for vegetables. My initial thought was to have them built using hardwood but the contractors I have asked for estimates say that these days they nearly always use treated softwood which, they say, gives a good life expectancy. Treated softwood is significantly cheaper than hardwood, but I don't want to have to replace them all in ten years time.

Anyone know how good the treated softwood is and what is a realistic life
expectancy?

Also, I see some people advocate lining the beds to increase the life but I have seen other comments that this traps water next to the wood and shortens the life.

It's all worry!
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Pa Snip
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Hi meliff

Reading your post it would appear that cost is not a major defining factor.

A few years back, about 5 or 6, I was told by a wood merchant that using treated timber would be more cost effective and highly durable.
I took their advice and even gave the timber extra treatment before making a number of 9inch raised beds.

Now experience has played its hand, if cost was not a factor to consider, I would not do the same again.

As one of my posts shows, viewtopic.php?f=8&t=12466
I have made some raised beds out of pallets. These I also treated and did line as the pictures show on that post

Apart from some fading in colour of preservative on some the pallet beds are fine, even though pallets are not made from highest quality wood, and just entering their 3rd year. Since the pallets cost nowt there was only the cost of the lining and preservative to take into account, plus the 1.25inch clout nails I used to secure the lining and corner brackets to hold the four sides together.

In the case of both types of beds made it seemed as if the corner brackets were the costly part.

The danger when people start to believe their own publicity is that they often fall off their own ego.

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Old railway sleepers are the most durable, but, that is due to creosote and tar ingrained in the wood. Some folk get wound up about "deadly toxic creosote". A more pressing issue is that tar does seep out in patches and lets say, doesn't do your clothes any favours. A cap across the top and down the outside would solve that.
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Pa Snip
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Indeed Peter, they are very durable. Costly mind but long lasting.

I just wonder where all these sleepers have been stored, it's years since concrete sleepers have been replacing wood. Are they still pulling them up from disused rail lines perhaps or are a lot of what we see today 'modern reproduction'.

The danger when people start to believe their own publicity is that they often fall off their own ego.

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I have 10 raised beds all apart from 1 are made from ex scaffold planks these where all past there best for what they where designed for, we paid £2 each for them, hardwood would be better but as a retired joiner the thought of using it for raised beds frightens me, you could use concrete panels and posts which would last a life time
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Another thing to take into consideration is how you want them to look. If you want them to look attractive and don't mind spending quite a bit on them there are some very good ones on the market, but if you want an economical D.I.Y. job you can knock something together from what ever materials you like as suggested. I have found that soft wood, even treated, doesn't last very long - up to 10 years. Perhaps I expect too much, and they may have lasted better with a plastic lining.

A very durable alternative is the concrete blocks (breeze block size) but with two holes through them from building merchants. I edged a path with these and planted the holes up with herbs which look lovely and to make a more attractive finish I brushed the outsides with a wet cement mix which weathers nicely. It would be easy to build a 9inch high raised bed from these.
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peter
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Robot's suggestion is good.
The slotted concrete posts and concrete gravelboards used with larchlap fencing panels.
I've used then for terracing my garden. If holding back soil you do need a decent length firmly fixed in the ground. Three foot in using an auger and setting with postcrete. The gravelboards come in 6" and 1' depths, they come plain or mock stone wall. Six foot posts with three by one foot deep sides is entirely practical and possible.
Posts are available as corners, T-junctions, intermediates and ends(1 slot only). So intricate layouts would be possible, just no curves. With end posts you could but up against a previous construction, provided that the foundations aren't in the way of your post touching the above ground side of the previous construction.

With nine foot posts you could even go 3' in ground, 3' high bed and 3' readymade cover frame, into which you could slot 2"x2" chickenwire covered 3'x6' frames and Chuck a net on top.


I can only see four downsides;

Cost
Weight
Easy to crack if not handled carefully
Six foot wide beds.
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Geoff
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I always ask "why raised beds?" Fashion or necessity?
melliff
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Thanks for all your comments.

I would prefer to stick to wood as I want the area to look attractive as well as productive. I also want to avoid railway sleepers because of the seepage issues.

Pa Snip: Based on your experience, if cost was no factor what would you build them from today?

Robo: Your comment about hard wood is interesting. My contractors appear to want to avoid using it, I assume because it is very heavy and difficult to work?

Robo/Peter: Concrete gravel boards sound good for the durability but I only want the beds 1 foot high. Do the posts don't come in that height?

Geoff: Why raised beds? I am a convert to "square foot gardening" for the manageability and productivity.

I guess I shall opt for treated softwood lined beds and hope for a 15 year lifespan which will see me out.

Martin.
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Five foot concrete slotted posts at my local fencing specialist are £11.45, corner £19.99, end £;13.96, 6" gravelboard £7.42 and 1' £12.10. Postcrete £4.79 per bag - allow a bag per post more if you use spade instead of auger)

6'x12' bed with 1' or 2' mini border fence come net support would be £204.20 plus delivery and installation (or buy an auger between £30 and £80)

Geoff I agree, but if you're going to do something do it properly. Actually make something strong enough to hold a raised soil level. All the raised bed s my plotholders make are actually 6" or 8" little fences whose bottom edge had gaps or barely touches the soil.
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Ricard with an H
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For all my outside construction in timber I use treated softwood, for the raised beds I use 8 X 2 and you don't need corner brackets if you buy 6 inch coach screws. Three in each end, you will also need a long series drill bit to drill into the end-grain and stop it splitting. As regards the timber rotting you must treat all cut ends with Ensele which is a paint-on treatment.

I'm told that farming timber has a heavier treatment and is designed to be outdoors whereas construction treated timber isn't as heavily treated. Farming timber is only available in sizes for fences and gate posts. Its' cheaper but the lengths are short. Gate posts are 8 foot or 6 foot. My log stores are all made with farming timber.

I can't vouch for that comment.

Scaffold boards are not treated, not the ones I use.

I recommend you use construction treated timber in the way I describe. I have some thats been going 15 years now in all weather, the only failures are where I failed to use Ensele on the cuts. When you drive the coach screws in use wax and try to afford stainless coach screws.

8 X 2 timber is just big enough so you drill 16mm holes in the top, place 15mm copper tube X a foot long in each hole (Don't forget treatment) at intervals and these will robustly support 25mm blue alkathene water pipe for your netting supports. Less than £30 for 50 metres plus the copper tube it's good value and strong.

I'll take some photos but it's XXing down with rain and blowing a hooligan right now.
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Ricard with an H
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You can't see the corner-fixing in this two year old photo but trust me, those six inch coach screws do a good fix. I glue 45 degree fillets on the insides of the corners though later beds I didn't bother. Corner brackets have to be galvanised and add to the cost by a lot, you also have to use either stainless screws or exterior plated screws. I don't know how long they would last.
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melliff
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Ricard with an H: Thank you for the excellent information. I assume you do not line your softwood raised beds? A lifespan 15 years would do me fine.

And thanks for the tip re Ensele.

Martin.
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Cider Boys
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Regarding raised beds but slightly off topic, does anyone know what the Planning Authorities attitude is to constructing raised beds on a paddock?

Barney
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As far as I remember, Cider Boys, putting raised beds onto a paddock changes the use from agricultural to horticultural, domestic at that, and would require planning permission.

But I am with Geoff: why go to all that effort to make raised beds? Beds can be created by digging the ground and/or heaping up suitable growing material on the same site which could easily be "raised" but not surrounded by anything. Saves time, effort and money. I think raised beds just invite nooks and crannies for nasties like slugs and woodlice!
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