Allotments 4 All
Allotment Stuff => The Basics => Topic started by: AndyTranter on February 09, 2016, 17:27:43
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Hi,any advice on raised beds for a newbie, ie size and depth,will be much appreciated.Andy.
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Hi there,
The important thing about a raised bed is that you need to be able to be able to access every part of the bed without standing on the soil - for most people that is approximately 4 foot wide while being able to comfortably access the centre but I make mine a little wider. With beds this wide - they can be as long as you like! I have mine in strips the whole length of the allotment - but you might want to make them broken up with paths in between.
Depth is another thing which is negotiable. Anything under one foot high won't benefit much from the added drainage and soil warming you get with raised beds. Between one and two feet is the normal range - but you have to remember that the higher you build it - the more soil/manure/organic matter you will have to shift. I can assure you that raised beds just eat up stuff and they never look like they're going to fill up at all! If you go for a 3 foot "no-bending" accessible bed you will seriously be there for weeks trying to get it filled with growing material. I made mine by digging the paths down and using the path soil to build the beds up ... but in seriously wet weather like we've had this winter the paths quickly become muddy canals.
If you're starting on a lawn then you can probably get away with the method of laying cardboard over the grass and building the bed above that - but if, like me, you're putting them on an overgrown allotment, I really recommend that you dig out all the roots thoroughly. Perennials like docks, bindweed and nettles will push their way up through at least 2 foot of bed and emerge triumphant and much harder to get at once they're safely inside a finished raised bed! It might seem like a pain now - but it's definitely worth doing!
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Without hi jacking the thread, can I also ask for suggestions for inexpensive retaining sides. I have just created 4 new beds approx. 11 feet by 5 feet each. I now realise they will need to to be raised but sleepers and similar from local wood yard would cost a fortune. It needs to be a neat job. Thanks in advance
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Yeah - that's the problem with conventional raised beds - if you make it out of timber that is too thin then it doesn't last very long - but decent sized stuff will cost a fortune to buy.
Most of my allotment raised beds don't have sides at all - they're just mounded up towards the middle like a ridge & furrow type thing. It's not as neat and sometimes the line between path and bed become blurred - but it didn't cost anything - works just as well and you don't get slugs and snails making a home in the sides. The places where I do have wooden supports for the sides tend to be where mice & voles like to tunnel under too.
When I've made them with sides I've either bought scaffolding boards from a place near me called Oxford Wood Recycling which they can cut to size, but they're still quite pricey. Otherwise it's skip diving which can yield remarkably good pieces of decent sized timber if you search properly.
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Like squeezyjohn I to don't use any sides although I did start with sides the length of the plot. It became very expensive. so within these lengths I just mound up the beds, mine are 4 foot by 10. I have well defined paths of just the natural ground, I edge these at the beginning of the growing season just to redefine the edges. In late autumn I just pile as much manure etc. onto the beds after roughly turning the bed over and let nature take its course. As stated it just seems to disappear. At the onset I did double dig each bed putting some good compost/manure into the bottom of the trench. I make sure that I don't stand on the raised beds although in practice this can't be helped. In the spring all that is required is a light forking over and the bed is ready for planting or sowing. Hope that helps.
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Might I suggest trying to source scaffolding boards from a local scaffolding firm? That's where I picked mine up from, OH cut them in half lengthways and they make great chunky edges.
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This might give you some cheap ideas,I used damaged scaffolding boards which were given free(lots of scaffolding firms give them away) and old decking boards
https://www.youtube.com/watch?v=Q1llKeOOXZo
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I definitely wouldn't use the method in that video! It isn't really a raised bed, it's more like a big wooden window box with a space underneath it. One of the best things about planting in the ground vs planting in pots is the fact that you hardly have to water once the plants get established roots going. A raised bed will give you the advantage of quicker warming and better draining soil while still having the benefits that deep-rooted plants in the ground have.
The video shows a nifty way of making cheap wooden troughs for planting. And yes if you're planting next to trees that would be a good idea ... but in the summer they will require a lot of watering just like plants in pots do.
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Scaffold yards can be a good source of cheap wood - they often throw out old boards that are past their best or you can buy damaged ones fairly cheaply - a coat of preservative and they can last years. Unfortunately a lot of them have caught on to the idea round my way and are now charging too much. We get a good deal as we get a load in at once. We also use a local Jewsons who leave off cuts and old stock in a pile to take away.
I don't build my raised beds that high - certainly not two foot. The amount of material required to cover a plot 2 ft thick boggles the mind..
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I definitely wouldn't use the method in that video! It isn't really a raised bed, it's more like a big wooden window box with a space underneath it. One of the best things about planting in the ground vs planting in pots is the fact that you hardly have to water once the plants get established roots going. A raised bed will give you the advantage of quicker warming and better draining soil while still having the benefits that deep-rooted plants in the ground have.
The video shows a nifty way of making cheap wooden troughs for planting. And yes if you're planting next to trees that would be a good idea ... but in the summer they will require a lot of watering just like plants in pots do.
I was thinking on the lines of just the sides and not having a bottom
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Hi, thanks for the ideas will certainly think through them all we do have a scaffolding firm nearby so will check that out first thanks again, Andy.
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I find beds raised a mere 20cm do have a dramatic effect on soil temps - in an average spring I get volunteer tomato seedlings - that never happened before - they aren't far behind the plants I buy.
It may be that my heavy clay soil is much more affected by improved drainage - it must take much more to improve better soils.
Keep a vigilant check on your local skips - 8 inch rafters/joists (20cm) are my holy grail!
You can get the same effect by nailing 4x2s together in a "bonding" pattern and they'll still outlast any floorboard - though floorboards are very useful on a sloping site (use them on the upper side of the bed where there's less pressure).
NB. the easiest source of topsoil for your beds is the path either side - but you need something to fill the trench you've made - a) free woodchip is just brilliant, but b) you can also chuck in any old branches and prunings as long as you cut them up enough to pack neatly - basically if it isn't dead straight you need to chop it into 50-80mm lengths.
I use a) on the allotment and b) at home.
Cheers.
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I use scaffolding boards; they raise the level about a foot, and last several years. Filling them is a massive job; I make mine four metres long - the length of a board - by three foot six wide. I could make them wider but that width fits the space nicely.
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Do you guys treat your scaffolding boards.
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I paint my ones with coloured woodstain to give them a bit of protection...my old free pallet wood ones lasted 9 years like this!
http://www.allotments4all.co.uk/smf/gallery/3629-200815212015.jpeg
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Thanks for that. I think this is the way to go for us
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I paint my ones with coloured woodstain to give them a bit of protection...my old free pallet wood ones lasted 9 years like this!
http://www.allotments4all.co.uk/smf/gallery/3629-200815212015.jpeg
Ask at your local amenity tip if they will "sell" you all the part used cans of the decorative fence treatment such as Fencelife or Timbercare. You want the water based non-preservative type. (Non toxic ). If they will play ball, select the fullest, and just mix them all together. It will be "brown", shade dependent on the ingredients! Bit of blue, green whatever. If you get the chance, get hold of some preservative type(such as Solignum) and soak the lower edges on the rainward side that is not where you will plant. Allow either to dry before you use, over paint or plant. I reckon 10 part cans assorted for a £1 should be your opening bid.
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this is my strawberry bedworks well
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Scored myself a dozen free scaffolding boards from a local building site yesterday - six 8ft ones and six 13ft ones, enough to build three beds. My old ones had practically disintegrated!
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My experience of timber sided raised beds is they they are a perfect homes for pests, slugs, ants, woodlice etc... also they don't last more than a couple of years... Try the concrete gravel boards used for fencing 6' x 9" ... builders scaffold planks, are probably treated with nasty chemicals :(
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My experience of timber sided raised beds is they they are a perfect homes for pests, slugs, ants, woodlice etc... also they don't last more than a couple of years... Try the concrete gravel boards used for fencing 6' x 9" ... builders scaffold planks, are probably treated with nasty chemicals :(
I put in timber raised beds in 2008, and am only just replacing them now. And the wood's much thinner than scaffolding boards!
The ends of the boards I cut look like untreated wood to me, but I'm in no way an expert.
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My experience of timber sided raised beds is they they are a perfect homes for pests, slugs, ants, woodlice etc... also they don't last more than a couple of years... Try the concrete gravel boards used for fencing 6' x 9" ... builders scaffold planks, are probably treated with nasty chemicals :(
Timber does have a limited life, but if it's free, who's looking gift horses in the mouth?
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I don't have any problems with pests in my raised beds either.....less compared to the open part of my plot. I did use nematodes for two years when I first started but do not bother now, it was easier to water over a confined area too.
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Timber also has the advantage of bring easily cut. I don't walk on my beds, so really they can only be maximum 4ft wide.
With concrete gravel boards you're stuck with 6ft wide beds.
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Scored myself a dozen free scaffolding boards from a local building site yesterday - six 8ft ones and six 13ft ones, enough to build three beds. My old ones had practically disintegrated!
Have a mental picture of stranded builders up on a higher level!!!!!
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Scored myself a dozen free scaffolding boards from a local building site yesterday - six 8ft ones and six 13ft ones, enough to build three beds. My old ones had practically disintegrated!
Have a mental picture of stranded builders up on a higher level!!!!!
That's funny! :D
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Timber does have a limited life, but if it's free, who's looking gift horses in the mouth?
I'm with Robert on this one - and I use joists when I can - they are mostly from 1930s properties round here and seem to be un-treated - they certainly rot but they are good seasoned timber 5cm thick so it takes many years. Yes they do harbour pests but the only thing that stops cheap gravel boards rotting much quicker is the fact that they are heavily pressure-preserved - which also sees off the slugs etc.
When my un-preserved joists do rot they go into the bottom of next deep-chip path I set up.
Cheers.
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Is there anyone here who has tried using breeze blocks as raised bed edges? I'm sure they're not the prettiest thing and quite wide, but they're strong, don't rot and there seem to be a never ending supply of them in skips outside houses being renovated!
I'm toying with the idea ... they are very heavy!
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Cinder blocks are lovely and light, you can also saw them to fit an odd gap. I've used them before for a cold frame surround. They also insulate in the winter, but keep the warmth from the sun like a storage heater.
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Old blocks (70s/80s) can be disintegrated very quickly by frost, but I've got some in my back garden that I bought 25 years ago and they are fine, despite being in an exposed position holding back claggy soil - and getting walked on.
The only reason I don't use them on the allotment is that they work best mortared onto a good foundation - and my site doesn't allow anything that 'permanent'.
Cheers.