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Lining a raised bed on legs?

drcatherinebakerdrcatherinebaker Posts: 15
in The potting shed
Hi Everyone, we have built a deep raised bed on legs out of treated timber and I'm not sure on how to line and what with as there's much conflicting advice out there. I have thinking of plastic around the sides and a fabric 'weed' membrane on the bottom but am concerned planks on the bottom will still get too wet? Any advice would be super helpful please. 
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  • drcatherinebakerdrcatherinebaker Posts: 15

  • FairygirlFairygirl Posts: 55,117
    edited June 2020
    Hi @drcatherinebaker - I'd line all of that with plastic, but put lots of holes in the bottom for drainage. If there are no holes in the base  [it doesn't look like it from your pic ] then drill some decent sized ones.  :)
    You can use old compost bags or similar, if you don't have anything else. Just staple to the sides just below the top. 
    It helps to prevent the timber rotting. 

    Just another thought - bed looks great, but you might want to add a little edging round the top, for aesthetic purposes. I did that with all of mine  :)
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • strelitzia32strelitzia32 Posts: 758
    That looks like proper treated timber, bet that cost a fortune! Treated timber can last 15 or 20 years outside. However as it will be wet due to watering more often than natural rain/weather would, it'll maybe be a little less. Either way I think you'll get plenty of use out of it. I have beds made from old pallets and crates, they are permanently wet through winter and soaked regularly through summer, and they have lasted years. 
  • Mike AllenMike Allen Posts: 208
    Personally, I would leave it as it is.  As a member has stated.  It appears to be treated timber, although I much prfer creosoted seasoned timber.  Never mind.  A possible life span of 20 yrs.   That's good.
    Weed membrane....why?  Where are any weeds going to come from?

    Yes.  Drill some drainage holes in the floor.  Fill up.  Sow/plant up and enjoy.
  • WilderbeastWilderbeast Posts: 1,415
    I'd just like to add something about treated timber it's over sold as lasting forever, as a builder we buy lots of this however there are different grades. This works on a scale of 1-5 bog standard treated timber has a limited life not that dissimilar to plain wood, the highest grade treated wood will last for the quoted many years. I'm not putting people off but I've seen tons of treated timber that has rotted away within 5 years. A better design is to make the base from a galvanized 1" mesh with heavy duty woven fabric laid over this gives good drainage but no timber base to rot, the side can be covered with a plastic membrane compost bags are very good for this. The planter does look great and hope you get it planted up
  • Blue OnionBlue Onion Posts: 2,995
    I would drill a number of 1” holes along the bottom, line in plastic, poke a hole were the holes in the wood are and pull the plastic a bit through so the wood is not exposed (it will cause a wrinkly bottom, but not a problem.. just make sure to allow for extra plastic before you cut).. that way moisture shouldn't be in contact with the wood.  Put some loose weave weed membrane over the holes to keep the soil in, as you are over paving.  
    Utah, USA.
  • FairygirlFairygirl Posts: 55,117
    The other reason for lining is, raised beds of any kind dry out more quickly, and bare timber draws the moisture away from plants. In the current climate, plants would struggle, even those which like drier conditions, as it would be difficult to keep them well enough hydrated. 
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • drcatherinebakerdrcatherinebaker Posts: 15
    Blue Onion said:
    I would drill a number of 1” holes along the bottom, line in plastic, poke a hole were the holes in the wood are and pull the plastic a bit through so the wood is not exposed (it will cause a wrinkly bottom, but not a problem.. just make sure to allow for extra plastic before you cut).. that way moisture shouldn't be in contact with the wood.  Put some loose weave weed membrane over the holes to keep the soil in, as you are over paving.  
    Thanks! That’s exactly what we ended up doing 👍🏽
  • drcatherinebakerdrcatherinebaker Posts: 15
    Thank you everyone. I did line it to keep the timber in good condition for as long as possible and did exactly what Blue Onion describes for the bottom with weed membrane to stop the soil washing out as planned. Hope it lasts for many many years. 
  • nick615nick615 Posts: 1,487
    One aspect that no-one has covered is the bottoms of the legs which are standing directly on to the slabs?  When telephone/electricity companies replace poles, they either leave the old ones lying by the road or put them up for sale to farmers @ £20 a pole to be used as gate posts etc.  They never remove the foot rests that the pole jockeys use for climbing and standing on.  Preferably after clearing it with someone, arm yourself with a 5/8inch open ended spanner and take a couple off - six screws in all and super galvanised!  You'll need to drill a pilot hole up into the centre of each leg to prevent splitting, but they'll keep the feet of your planter well clear of the ground and can be adjusted to ensure a level base.  Sod's/Murphy's Law says there are never any about when you want one, hence the need for opportunist salvaging, but I keep my eyes open and always have a few 'in stock'.  They last 'for ever'!
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