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Sinking soil in raised beds - how to fix once planted up

htyashtyas Posts: 30
in Problem solving
Hi, our raised beds are now nearly 4 years old and the soil has sunk about 10-15cm. Not only does this mean we can see the black liner in winter but some of the smaller plants are now not really visible e.g. cyclamens. I'm really unsure how to refill the bed though. Whilst I don't mind disturbing some of the perennials (excepting the hellebores) as they need dividing anyway, there are 4 good-sized shrubs which would be a real task to dig up and a real shame too! (rose, mock orange, mahonia, sorbaria, and sweet box). The sweetbox is probably too big to dig up anyway. 
Would gratefully receive any suggestions!

Posts

  • parrotfeather*parrotfeather* Posts: 188
    I find that I have to top up raised beds every year and certainly if you filled them with organic matter this will be the case.  With ornamental plants the best solution is to mulch, preferably with something bulky which will take a bit longer to rot down.  I use a mixture of home-made well-rotted compost and sterilised organic horse manure from Mr Muck but have also tried the compost from the local recycling facility which was OK...weed-free if a bit thin, leaf mould and well-composted bark.  Your soil has sunk quite a lot so you may have to do this in stages over a long time to avoid swamping the plants. I think that the tiny stuff like the cyclamen will have to be carefully lifted and replanted in any case but the roses and shrubs should be OK if you avoid putting a thick mulch close to the stems and add to the level gradually.
  • NollieNollie Posts: 7,529
    I did exactly the same as @parrotfeather* suggests in a raised bed for a similar slump in soil levels, lifted and replanted some perennials last year, left the shrubs and roses in-situ, mulched heavily leaving a circle free around the stems of the shrubs/roses, then just repeated it today after some good rain and will do so again next year. The mulch gradually slumps into the circles, but as it’s a slow process, the stems haven’t rotted. You are essentially mimicking nature, as the soil level of shrubs and trees in the wild gradually have leaf mould from deciduous trees building up over the years.

    Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
  • htyashtyas Posts: 30
    Thank you both. Any recommendations for the type of mulch that would last the longest? (Home-made isn't going to be an option!)
  • K67K67 Posts: 2,506
    I used composted bark last year and it looks very good still but I will fork it over and put on manure around my roses, climbers and shrubs as already suggested. 
    The raised beds need mulch every year to keep them topped up as the soil still sinks but by doing it annually you don't have to swamp the plants.
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