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Sinking raised bed

I am looking for advice. I have a long raised bed about 8 metres long made out of stone. (700mm deep and about 800mm wide) Over the years I have added evergreen shrubs to shield the view of our neighbours cars. As this season is progressing it has been noted that the soil level is about 150mm below what I desire - erosion and compression over time. I now want to bring the level of the soil back up to allow for new plants to grow over the edges. How do I raise the level of the bed without covering the top of the roots and thereby causing damage to the shrubs? I have seen advice that warns you against this with raised beds around existing trees. Thanks for your help Peter


  • wild edgeswild edges Posts: 9,942
    Usually you can't surround the trunk of existing shrubs with soil but it's ok to build up soil over the roots. Ways to get around this are to surround the trunk with large stones to match the bed while leaving space around the trunk or build up the bed in different levels. Can you post some photos so we can see what you're dealing with?
    Tradition is just peer pressure from dead people
  • NollieNollie Posts: 7,336
    150mm is quite a lot, so short of digging up and replanting the shrubs (ideally when they are dormant and not growing much) Wild edges’ solution does work the best, so long as you keep the raised soil away from the trunks. I used a large, deep brown plastic plant tray around a tree, with the bottom cut out and sliced down the side so I could bend and slip it around the base to hold the soil away from the trunk - it’s then invisible as it blends with the soil. I then put some brown gravel (just a shallow layer) in the plant ring which also aided the disguise!
    Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
  • P5brownP5brown Posts: 2
    Thank you Nollie and Wild Edges, you both have given me a starting point to kick start the old grey matter. Last year was a rough year for me so the loss of height went unchecked but now things are getting back to normal (for me at least) I can start to address the areas that were neglected last year. The shrubs in question are things like Himalayan Hawthorne, Japanese Laurel, Mahonia etc. Please stay safe and enjoy the nature you are custodians of.  
  • LoxleyLoxley Posts: 5,416
    Roots will grow at a level where they can access oxygen in the soil, and the further down you go the less oxygen there will be. So it would be a good idea to build up the levels a little at a time, and give the roots time to adapt. If you can build up the levels with something like coarse crushed stone that might be even better.
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