Raised Flowerbeds

I'm thinking of creating a couple of raised flower beds using old railway sleepers, and I've a couple of questions...

The sleepers are made of wood, so when I'm setting them in place, do I just set them directly onto the soil, or will I need to set them on something else (Concrete? Gravel?) to give them a stable base and/or prevent them from rotting too quickly?

Similarly, do I need to think about "lining" the inside of them with something to help prevent them from rotting? And if so, what?

Also, do I need to put anything in the bottom of them for extra drainage? or will the fact that they're open to the normal garden soil (or sub-soil) be good enough?

And finally, is normal garden topsoil good enough to fill them with? or do i need to add some sort of compost?

Any advice gratefully received.

 

Hi ballinran and welcome, if they are old sleepers then they will have been treated with creosote, so they wont rot but you will need to line them with heavy duty polythene to stop the soil being contaminated with this creosote. As for the soil, ordinary garden soil is fine for filling the beds but before you do so dig over the bottom of the bed first, don`t forget you are making DEEP beds. A fact you may not know, a deep bed 10ft long by 4ft wide, if properly managed, will feed a family of 4 for a year, also the Chinese have been using deep beds for thousands of years.

 

I agree with David - that's sound advice. But I am amazed at the fact that a bed 10 x 4 will feed a family of 4 for a year.

David, what is the importance of a deep bed as opposed to a raised bed? And can you have a deep bed that is not raised?

 

Peter, they are one and the same, just differant names.

 

Peter, when growing veg in deep/raised beds your planting distances are so much smaller, for example, onions would be planted 4" apart in a bed instead of the 8" in the ground. Runner beans would only be about 3" apart. You can do this because the roots have a good depth of soil to root into, about 15" to 16" inches instead of the normal 6" to 8". But as I said the beds need to managed properly.

 

Thanks David - that was the answer that I was sort of expecting. But on the other hand I thought that plant roots grew to a natural depth irrespective, as long as the subsoil is not too compacted.

Are you saying that extra deep digging, assuming the sub soil is good quality, will make plants root much deeper, and does this mean larger plants in the border for instance?

 

Peter if you are putting in a "raised bed" then you are building it on existing topsoil, so you turn that over then add more topsoil to top the bed up. So, basically you are growing plants in a TOPSOIL depth of about 16"

 

Yes - we are really talking about depth of topsoil - which varies anyway from place to place. I am thinking about my front garden, which I dug up this autumn. I dug it to a depth of about 18 inches. I must have mixed some subsoil with the top soil - but not much. I put a lot of organic material in, including three years worh of newspaper, a ton of manure and 60 bags of garden compost, plus sharp sand and small gravel. The level in places is a now foot higher than it used to be. I guess I could be feeding a family of 100. :D

 

Thanks for the info.

That's interesting about feeding a family of 4. The area we're building will be about 10ft * 5ft and there's 4 of us, so we should be able to grow all the veg we need. (Although given that 1 of the 4 is a teenage boy, we only need veg for 3 :D )

My wife's talking about ornanmental grasses and the like, maybe we should think about doing some veg in it. as well? Hmmmm.

 

ballinran, may I suggest you invest in a book on the subject. This will tell you the best things to grow this way and their planting distances.

 

Folks,

We're eventually getting round to this (next weekend weather permitting).
So far we've established that the old sleepers, soaked in cresote won't rot quickly from contact with the soil, but what if i use "new" pressure treated ones? (They're cheaper, and we don't need to worry about the cresote leaking out into the soil and they can be used as a bench too)


Obviously they'll not last as long, but is it still OK to put them straight onto the soil? or should i look at putting them on gravel "blinding" (if that's the right word?).

They'll be filled with soil (obviously), so will it make any difference if the underside is in contact with the soil as well?

 

I wouldn't worry to much about the rotting. Even if you put them on top of something, they will still be outside in the wet and will ultimately rot anyway - but not for a long time.

The main thing I was going to say is that if you are doing it from scratch add loads of organic matter, and possibly grit/sharp sand if the topsoil you are adding is slightly clayey. It is so much easier to do it at the initial stage, when there are no plants.

 

Aye, I'm beginning to think that's the case.

looking on t'internet for examples of "how to do it" i've only seen one case where they put a concrete bed below the sleepers, mostly they're straight onto the soil

Our soil is pretty good - somewhere between "silty" and "loamy" i'd say (I looked those terms up) so we won't need the sand, but I'll mix in some garden compost or somesuch. We want to be plant in it straight away, and hopefully get something out of it this year.

 

Not wanting to hyjack but what is a good book on raised bed husbandry?