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Achieving perfect soil drainage in pots

Hi Folks

Thanks for all the helpful tips recently.

I wanted any general tips in order to avoid water-logged soil when using pots.

I have been using styrofoam, pebbles, bits of broken pots to help with drainage and a combination of John Innes 2 and multi-purpose compost as a 'standard'. In some instances this seems to result in poor drainage which doesn't seem to resolve particularly well.

How can I resolve this? It seems I need something more 'fibrous' in upper layer perhaps?



  • FireFire Posts: 17,116
    edited July 2018
    I personally doubt if the crocks and pebbles do very much to help drainage. Grit and/or some horticultural sand is usually advised for mixing into the compost. With which plants are you noticing a problem and with which kind of pot? The problem with pots at this time of year is generally that they dry out too fast, not that they hold on to too much moisture. Are you noticing mould on outside pots?

    I have also sliced my hand badly on shards in the past, even when I cover them with weed membrane.
  • Are Perlite and Vermiculite options?

    I've planted my struggling Raspberry canes as above. As I've watered them lots, whilst also kept them in the shade, there doesn't seem to be any drying out. When watering now, it seems to 'pool' and drain very, very slowly.

  • wild edgeswild edges Posts: 9,367
    That experiment on crocks is a crock if you ask me. It misses the point of crocks and doesn't test drainage in any meaningful way. I use a layer of grit at the base of a lot of my pots and if you don't use a crock over the hole the grit gradually falls out over time and the soil plugs the hole up.

    Do you need good drainage for any particular plants or just in general?

    I've started using Melcourt potting grit mixed with john innes for alpines, sedums etc and it's excellent stuff. It's got a much finer texture than most grits but is a step up in size from sharp sand. it makes it much easier to mix into soil for smaller pots especially. My plants are doing really well with it this year
    Tradition is just peer pressure from dead people
  • FireFire Posts: 17,116
    The use of a piece of crock over a hole to stop the soil falling out, that's not to do with drainage - roots sitting in wet. You could just as well put a layer of weed membrane over the bottom of your pot.
  • wild edgeswild edges Posts: 9,367
    Weed membrane would plug a hole better than soil would. If you've got a terracotta pot with one hole, for example, crocks hold the soil away from the base of the pot and give multiple drainage points from the soil. Without crocks the soil compacts into the hole and forms a slow draining bung.
    Tradition is just peer pressure from dead people
  • Dirty HarryDirty Harry Posts: 1,030
    I layer the bottom of the pot with stones from the garden, works a treat.
  • BijdezeeBijdezee Posts: 1,484
    I add perlite to my compost. Seems to work ok. 
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