New beds over paving?

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This topic contains 5 replies, has 3 voices, and was last updated by  ElizaD 1 year ago.

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    Hello Charles and all

    As usual at this time of year I have more plans than room so am thinking of converting part of my sunny patio to a couple of narrow (say 2ft to 2ft 6ins) beds so that I could accommodate tomatoes, courgettes, cucumbers, beans etc in summer and brassicas and salads in winter.

    I know when my neighbour built a garden room that service pipes underneath adjacent paving were not as deep as they should have been and presume my patio to have the same problem. So, I’m wondering would I be better to have deeper (say 12″) sides to my beds? And, would I be better just building the beds over the existing paving slabs or removing them?

    Any thought on this greatly appreciated as I’m fast running out of room! Again!




    Just bumping this one up!




    Hi Eliza

    Just to keep your post alive …

    I think it is better to remove the slabs.

    If you have 2’x2’slabs you could lift a few to give a 2′ wide bed, and also scrape out scalpings/sand/mortar or whatever the slabs sit on; removal of slabs and foundation will give several inches extra depth and easy access to the soil below for the roots of your crops. Removing a double row of 18″ square slabs would give a 3′ wide bed. If the line of your service pipes coincides with your new beds and the pipes are encased in a few feet of concrete then you will have no soil to access but this is highly unlikely.

    If there is access to soil below I doubt that you will need deep raised beds and one could argue, in a best case scenario, that removal of slabs and foundation would give enough depth for several inches of compost over the soil with no need for a raised bed. It all depends on what you find below the slabs.

    There is fear of roots interfering with underground water pipes but, as long as you intend to grow annual veg rather than a willow plantation, all should be ok.

    Good luck with your project

    • This reply was modified 1 year ago by  John.


    Thanks for this John.

    Yes, water pipes are the problem as they are absolutely nowhere near the required depth. My neighbour found this out when he was building a small garden room and struck one at a depth he could not believe. I had also found one previous to this when putting a small pond on the edge of my patio – pipes criss-cross this area. I know there is soil there from digging out the pond. This pond area has now been filled in but I’m thinking of this same spot for the narrow(ish) raised beds.

    It would enable me to better rotate a few summery things mainly, e.g. toms, courgettes, beans, maybe cucumbers and it would also be handy for overwintering salad stuff and a few spring cabbages. I don’t think roots from these crops should cause too much of a problem but if anyone thinks differently please let me know! I have decided I will remove the slabs as you suggest but put in 6″ raised beds just to be on the safe side.

    Thanks again for your input.



    Don Foley

    Hi Eliza,
    I think removing the slabs is the right way to go. Invariably they will be sitting on sand/grit/gravel, all excellent drainage materials.
    As far as the Tomatoes are concerned I would go for deeper, 9″ minimum but 12″ preferably. The 6″ depth is really only 5″ if you allow a 1″ gap between top of soil and top of the beds for watering (you don’t want the water to run off with soil onto the surrounding paving) or a mulch for instance. This is little more than the depth of a grow bag. Whilst that depth is adequate for Tomatoes you will invariably be doing a lot of watering as it will dry out quickly. Deeper beds dry out slower but also give roots more room and helps anchor the plants better (they will still need additional support if they are cordon cvrs and indeed some bush types need this additional support also).
    Beans will be fine with the 6″ depth. I can’t comment on the Cucumber or Courgettes as not liking them myself I have never bothered to grow them.



    Thanks Don for your inpu, I will give it some thought about making the beds deeper then. I was concerned that deeper beds may dry out more and become a home for the ants that love this very sunny area. Still measuring up so no final decision made yet. Any further thoughts welcome!

    Many thanks, Eliza

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