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Raised Bed : Filling and Growing

Hi all,

First time poster, so hi, wave, etc. I've just finished building a raised bed for my lovely wife. I'm more a woodworker than a gardener so my idea of a raised bed is from my mind's eye, not from experience, and having built it I then realised I need to fill it. As it turns out it's quite large, 2.4mx1.2mx0.5m, c. 1m³ internal volume.


I'm not one to ask without doing some research, so I've pulled together my thoughts and am looking for some advice.

1. Lining

The raised bed is built on an area that has been disused for sometime, it's sited next to a holly tree (in the background) and next to where a Eucalyptus tree was (chopped down as was getting very tall and is too close to house). I dug the ground over, down to about 10cm and sieved out all the roots, then levelled and tamped down. The area has been covered in weed control fabric as I'm going to put large pebbles around the bed, and I've lined the bed in the same fabric to stop any soil getting between the sleepers (new untreated oak, so not worried about contamination of the soil).

Question 1: Should I cut out the weed control fabric in the base of the bed? The benefit of the fabric is that it may help prevent the tree roots growing up into the bed, the downside seems to be that it may prevent crops grow deeper than the bed depth (50cm) and also prevent worms getting into the bed.

2. Filling it:  

Initially I was going to just buy a bulk bag of topsoil, until I found out that i'll need potentially a couple of bulk bags which could set me back over £100 and that topsoil on it's own is not great for growing veggies in. I understand that I need a mix of soil and compost with some other bits added, ie fertiliser etc. I have also read about the lasagna method, ie throwing a load of stuff in the bottom to rot and putting a layer of soil/MPC on top. Through all my ongoing projects I have lying around:

- a huge bag of larch wood shavings (all untreated wood)

- lots of rubble sacks full of tree roots, leaves, top scrapings. From building a shed foundation where i had to dig the area over and sieve out all the dross.

Question 2: I was planning on throwing the shavings in the bottom, then the old roots/leaves/scrapings on top of them, then filling the remainder (at least the top half) with soil/MPC mix. Does this sound sensible?

3. Growing stuff:

Question 3:  With a bed of these dimensions what/how much should I (well the wife and kids; I do woodwork) be able to grow. Could we realistically grow a significant amount of veggies, or should we understand that this is just playing at the edges.

Many thanks in advance for any advice.


PS: Apologies for the essay!


  • pbffpbff Posts: 433

    Hi Fitz,

    Welcome to the forum!

    Q.1: I would leave your weed control fabric in place. Many people construct raised beds on patios or other hard surfaces and so the bed has no contact with the earth. Think of your bed as a very large trough or container. Most vegetable crops will be happy in this depth. The fabric is woven polypropylene so is permeable to water, meaning you shouldn't get any water-logging problems, but if it really bothers you, just cut some slits through the fabric in the base.

    Q.2: If you use un-composted materials to fill the lower part of your bed there are 2 main points to consider a) as the materials lower down decompose they will reduce in volume and cause the level of the growing media in the bed to sink, which will result in you have to top up with 'proper' compost on the surface anyway b) the decomposition process uses up nitrogen and so if you are growing crops, especially leafy ones, in the bed you will definitely need to add nutrients to compensate for that. I would suggest putting a layer of grit/stones/rubble/upturned turves at the base of the bed, then you could add well-rotted farmyard manure (if it is available) - you could also use fresh farmyard manure, but in this case, do not plant anything in the bed for a few months until the manure has rotted, as it will burn the plant roots, leaves/leafmould and any waste compost from containers (provided that the plants previously in them were not affected by pests or diseases). Then fill in the rest with a mix of quality topsoil and MPC. You could also add vermiculite, which improves the porosity of the growing media. If you use the larch shavings, do make sure that they go at the bottom, but mixed with some other nitrogen-rich organic matter e.g. grass clippings. Wood takes up an awful lot of nitrogen in the decomposition process and larch may make the growing media more acidic, which is not great if you intend to grow things like brassicas.

    Q.3: If you're selective as to what you grow, you should be able to get quite a variety of vegetables out of this space - not enough for a family to be exactly self-sufficient, but still quite good. My advice would be to choose crops that really taste good for being home-grown, ones that mature quickly, that don't grow too big (so you can sow, plant, grow, harvest and sow another type of crop for variety) and are reliable in our climate. Suttons seeds offer a range of seeds for small spaces that I would highly recommend. Even if you have a large space, it's worth growing the small spaces range so that you can grow more different types of crops in that space! Dwarf French beans, broad beans, leaf beets, carrots, kale, lettuce, spring onions, pak choi, peas, radish, rocket, etc will all grow well in a raised bed.

    Get a copy of Alys Fowler's book, 'The Edible Garden'. It is a brilliant book with great advice on growing plants in spaces that you didn't even know were there. It also has great recipes for cooking all your goodies!

    James Wong's 'Homegrown Revolution' is also good, especially if you fancy growing some more unusual vegetables, fruit and herbs.

    I hope this helps!

    Good luck and happy growing.

  • FairygirlFairygirl Posts: 54,353

    A general mix of soil and compost will be suitable for most things. You can add extra nutrition to the mix as and when you need, and depending on what you eventually grow. I wouldn't add the shavings. 

    More important is how much light and shade the bed has, and most important of all, what do you like to eat? Not much point in growing fabulous beans, for example, if no one likes them  image

    Looks like there's quite a bit of shelter form a building too - you'll have to make sure you water well enough too, if the bed won't get a lot of direct rainfall. Some crops will need rotaion too, to prevent a build up of pests and diseases. 

    2.4m x 1.2 m might seem quite a lot of room, but it isn't really. You might need another one image

    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • pbff and Fairygirl. Many many thanks for your super replies! I have the confidence now to:

    - Leave the weed fabric in place, although i will cut a few small doorways to give the worms entry points.

    - Take the shavings to the dump, fill the bottom of the bed with my bags of other garden waste, fill the top with a soil, compost mix and some manure if I can get it.

    - Leave the whole lot to mature over the winter, then get on with growing in the spring.

    - Add a couple of books to the wife xmas list.

    - Build a second bed (i have the sleepers and it was always in the plan). The bed location can be seen better in the picture below. The sun circles the sky behind the position of the photo so the bed gets the sun from mid morning to late afternoon, it's about the best of a bunch of bad options tbh! The second bed will go perpendicular to the first and replace the sand pit, paddling pool and bushes.


    Thanks again for the advice.


  • FairygirlFairygirl Posts: 54,353

    I only grow the things I like to eat and have room and time for, so it's mainly salad crops here Fitz.

    Lettuce will grow happily with a bit of shade - in too much sun it tends to bolt anyway. Things like spinach can be the same. Rocket seems to thrive in any position in my garden, including a lot of shade. If you like using herbs - chives will be happy with less sun too. I used to grow mangetout in a previous garden and they were happy enough with a little shde too. 

    Strawbs in as sunny a spot as possible. 

    You'll get an idea of what works as you go along. There are loads of expert people here regarding growing fruit and veg, so don't be frightened to ask away with what suits where. 

    It's all a very enjoyable learning curve image

    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Hi Fitzroy,

    I would absolutely compost the shavings, mixing in grass clippings as they become available. Wood shavings break down much faster than wood chips, they could be usable by next March if started now. 

    Composted shavings attract worms and make a brilliant mulch. You'll want to mulch your raised bed, since it can dry out fairly fast.

  • remacremac Posts: 6
    Help. My husband has just built me  a raised bed 8x4 and 18inches deep on the lawn with a double covering of strong carboard at the bottom. I then added 180 litres of farm manure and 1.000 litres of organic compost and dark rich topsoil on top. I still have 6 inches to go before the bed is full so I asked a colleague if I should order mulch to top up the bed but when he heard I wanted to plant winter vegetables. parsnips, carrots, swede, onions and cabbage he told me root vegetables wouldn't be any good because of the manure. I really want to grow root vegetables but I am in such a two and eight now I don't know what to do. Please advise.
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