Raised Beds around trees.

Hi, I've just bought a new house, with some protected trees in the garden, I'm looking to add raised beds around these trees. But I don't want to cause any damage to them.

My current plan is to make the raised beds, more like large garden boxes, with a 2-3" gap between the tree trunk and the inner wall of the bed/box, so soil will never be in contact with the bark.

Additionally I plan to have a bottom in the bed box, around 4" from the ground to allow an air cavity so the tree roots under the bed can breath appropriately, with a permeable membrane on the ground to prevent weed growth under the bed.

These trees are already large and well established so I'm not sure if this is 100% necessary. 

Any advice or thoughts on my current plan would be much appreciated. 


  • ObelixxObelixx Vendée, Western FrancePosts: 16,744
    It sounds to me like a great deal of work and investment in materials to end up with shaded beds which will need watering all the time because of the rain shadow.   Also, the construction of something strong and stable enough to endure is going to involve posts in the ground at regular intervals and how many trees do you know with regularly spaced roots?

    I would think again about making beds in the sun away from the trees.  If this isn't possible, think about raising the crown of the trees to increase light and rain to the ground below.    Can you post a photo or two?  
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • nutcutletnutcutlet PeterboroughPosts: 25,981
    In addition to Obelixx's comments. Don't forget that tree trunks continue growing in diameter for their whole life
  • Lizzie27Lizzie27 Bath, SomersetPosts: 3,318
    What about a circular bench around the tree trunk so you can sit in the shade on a hot sunny day instead of plant beds? 
  • Thanks for all the input everyone. 

    As for moving the beds out of the shade, the majority of the garden will be shaded as there are a total of three trees, which would cover most of the garden in mid summer. 

    A few posts may be necessary to sure the beds up, however having a base to them to allow the air gap below the soil level should make them sufficiently strong to prevent warping.

    I'm planning to leave an air gap of several inches around each side, to allow for air circulation and a littler future proofing. However reworking the beds in 10 or so years is acceptable for me.

    I'm considering a bench around one, but as there are a total of three trees, I'd have some left to do something with. 

    The house is still being completed so I don't have an accurate picture currently. 

    Thanks again for the input, if anyone has any other ideas I'm all ears :)

  • ObelixxObelixx Vendée, Western FrancePosts: 16,744
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • NollieNollie Girona, Catalunya, Northen SpainPosts: 2,171
    Hi Nathan,

    So the trees are protected, by a tree preservation order? It might be worth first investigating what is permitted under the TPO, for example, raising the crown, as Obelixx says, by removing the lower branches, also to what extent you can prune back the trees, to reduce the overall shading of your garden. That way you might create some areas that get sun for at least part of the day.

    We normally think of raised beds as boxes sitting on the ground, but your idea is to have raised beds on short stilts - kind of ariel beds? I like that idea, you could even have the beds at different heights to create added interest.

    It depends how fast growing the type of trees you have, and how much space you have in general, but I think a gap around the trunk of 3-4” is too small and I would allow at least 6” or ideally a foot all around. Once they are planted up, with some taller shade loving plants nearest the trunk, you won’t see the gap.

    Wet soil is very heavy, so they would need to be very sturdily made, with a strong, rigid bottom, perhaps from perforated metal with a layer of gravel (bigger than the diameter of the perforations for obvious reasons!) at the bottom to allow drainage. A wooden base would sag and rot pretty quickly. Dont make them too shallow, either, at least a foot deep, and remember that off the ground they will dry out much more quickly so be prepared to water frequently to keep the roots of your plants moist.
    The corner posts can extend to form the legs, which could sit on the ground on small base plates rather than sunk in - guaranteed there will be a tree root in the way. The legs could be adjusted to height depending on the ground levels around the trees and either made of metal (Ikea table legs cut to size?) or treated timber posts that sit in a metal base plate, again to prevent rotting too quickly.
  • ObelixxObelixx Vendée, Western FrancePosts: 16,744
    Raised beds of a adequate width and depth will cost a fortune seriously impact the amount of rainwater getting to the tree roots.  I think this project needs a re-think.

    On the other hand, you can raise and thin canopies of trees to allow more light, air and rain to the ground below and a woodland garden can be a thing of beauty.  Far better to go with what you have.

    Again, we need more info on the trees - name/variety, age, size - and a photo.
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
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