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Does this blockwork bed need more drainage?

Hi all 

We've just finished a major build and have got the bare bones of the garden built. 

This 600mm deep, 3m long bed is probably going to be mainly herbs. The base is sold concrete (after a design change!), water does drain gradually but will this be OK without having to drill holes anywhere? I will have rubble I can fill the base with before soil too which may help. 

Any help on how to prepare this for planting would be really appreciated. We're pretty new to planting so need all help we can get over the coming months!

Ta! 
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Posts

  • Andy19Andy19 Posts: 671
    Whatever way the ground runs off I would drill some weeping holes near the bottom of the wall to help the water run off.
  • wild edgeswild edges The north west of south east WalesPosts: 7,569
    Retaining walls also need weepholes too you know...  What's the plan with facing all the blockwork off? It does need drainage but you need to think about where the water will go and what staining it might leave behind.
    A great library has something in it to offend everybody.
  • CaddyCaddy Posts: 5
    Thanks for the input all.
    Like I said the bed was a bit of late change of plan so drainage wasn't a thought. Behind the small retaining wall is loosely packed rubble then earth, not sure if that helps or hinders. We're actually pretty much down to bedrock below that concrete so not sure whether to drill straight down.
    Also we're still to decide on how to face the blockwork. 
  • FairygirlFairygirl west central ScotlandPosts: 46,485
    I'd agree with the others- you need drainage/weep holes
    It's worth getting them in before you go any further. If you have them right at the bottom, that's probably the best solution.
    If it's for herbs, most of them like quite sharp drainage, so your mix can be largely grit and soil. Don't do the classic thing of a big layer of gravel at the bottom, as it can easily just become a sump. You can still put some rubble in the bottom, but make sure the planting medium is right too.
    However, you'd be better making some decent holes in the bottom, as well as weep holes, and you can cover those with landscape fabric or similar to prevent your soil disappearing down the holes and clogging them. I'd also put that over any gravel/rubble you put in the bottom. It's similar to what can happen in pots - soil can easily clog drainage holes.

    I would have thought you would be rendering the blockwork?
    It's a place where beautiful isn't enough of a word....


  • CaddyCaddy Posts: 5
    Fairygirl said:
    I'd agree with the others- you need drainage/weep holes
    It's worth getting them in before you go any further. If you have them right at the bottom, that's probably the best solution.
    If it's for herbs, most of them like quite sharp drainage, so your mix can be largely grit and soil. Don't do the classic thing of a big layer of gravel at the bottom, as it can easily just become a sump. You can still put some rubble in the bottom, but make sure the planting medium is right too.
    However, you'd be better making some decent holes in the bottom, as well as weep holes, and you can cover those with landscape fabric or similar to prevent your soil disappearing down the holes and clogging them. I'd also put that over any gravel/rubble you put in the bottom. It's similar to what can happen in pots - soil can easily clog drainage holes.

    I would have thought you would be rendering the blockwork?
    Thanks for this really helpful. Might get all the weep holes drilled tomorrow the lay some landscape fabric down. We probably will render the walls. Would there be any issues with render and potentially moisture penetrating from the back of walls? 
  • Andy19Andy19 Posts: 671
    As Rik56 says would also make a great pond water feature.
  • CaddyCaddy Posts: 5
    Andy19 said:
    As Rik56 says would also make a great pond water feature.
    Yes we did think that! though we have a rather mischievous water loving border terrier who I not sure we could trust to stay out of it! 
  • Andy19Andy19 Posts: 671
    Put a wire frame over it not hard to do keeps kids, fish and animals safe.
  • FairygirlFairygirl west central ScotlandPosts: 46,485
    You can get waterproofing paint etc for blockwork, but you could just line the back of the blockwork with plastic if you're concerned. I remember using something at a previous house when we did a deck at the back of the house, and I left a section for planting. We painted the bit of house wall. Hubby might have got it through work at the time. Thompson's Water Seal or something like that? 

    It might be difficult to get suitable stuff at the moment though, so you might need to search around a bit.
    It's a place where beautiful isn't enough of a word....


  • CaddyCaddy Posts: 5
    Thanks for all the input. Hope you are all keeping safe. 

    We want to render most of the other walls we have (pics attached) but been a bit handicapped because unfortunately our builders have back filled them with rubble without any thought for waterproofing in prep for render.

    Though rubble means drainage is good away from the back face I'm now thinking I'll have to pull all the backfill out (!) and damproof somehow. My concern is just using a membrane will result in this getting ripped when the rubble goes back in. Would it be crazy to use a panel material as well as the dpm sheet that will be more robust? A correx type or even cheap wood like osb that would rot away over time but protect the dpc plastic initially? DPM paint will probably be costly and I don't think it would work due to gaps in the mortar on the back face.

    Any input would be much appreciated!

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