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What is grit?

I am a big fan of Gardeners World....but I live in the Pacific Northwest of the US.  On the show grit is often recommended to add to potting mix.  Based on searching past discussions, I assume that it is washed salt-free sharp sand ....but sometimes it looks like small pebbles.  A search on Amazon for gardening grit shows results for vermiculite, perlite, pumice.  I don't think any of these are the same as what the Brits call grit.  Any insight?


  • Hostafan1Hostafan1 Posts: 33,184
    basically it's any " stone" crushed to a certain size. ( same size as perlite / vermiculite ) a few mm in size.
  • FairygirlFairygirl west central ScotlandPosts: 48,054
    Slightly heavier than the grit in rough sand.
    As @Hostafan1describes- it's crushed stone. Any bigger than that and it would be described here as gravel  :)
    It's a place where beautiful isn't enough of a word....

  • ObelixxObelixx Vendée, Western FrancePosts: 28,400
    Bigger than sand, sharper shapes than sea-washed pebbles.  It's often a by-product of quarried stone and is graded to size.   Some is used in fish tanks, some for covering compost in pots of trays or seeds, some as a mulch for succulents in pots. 

    Vermiculite is a good alternative for seed trays but not perlite as that floats away.  
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • Pete.8Pete.8 Billericay, EssexPosts: 9,701
    edited October 2019
    The horticultural grit I often buy is granite chips or what looks like crushed pebbles, both are quite sharp and the size varies between about 2-5mm
    Avoid anything with limestone as it breaks down and makes the soil alkaline.

    Vermiculite is good for seedlings and I use it to cover very small seed, but it breaks down to nothing in a few months.
    Perlite lasts a season or two before it breaks down but grit lasts forever so is best for garden or long-term planting

    PS - also worth mentioning that both vermiculite and perlite weigh next to nothing whereas grit is very heavy.
    And - welcome to the forum :)
    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • LynLyn DevonPosts: 21,103
    This is the sort of grit I would buy to put on top of plant pots. You see the size of the stones on the bag. 1 - 5 mm

    Gardening on the wild, windy west side of Dartmoor. 

  • Hostafan1Hostafan1 Posts: 33,184
    Forgive our bad manners:
    Welcome to the Forum @contact57
  • Thanks for the info.  It is strange that this common soil amendment isn't offered in the US. Perhaps because England has mainly clay soil.  My native soil is all sand so I have great drainage.  I am building lots of raised beds so am creating soil. I can get crushed basalt that is 6 mm or less in particle size.  Would this work?  
  • DovefromaboveDovefromabove Central Norfolk UKPosts: 81,465
    No clay here ... gritty alluvial loam over chalk bedrock ... but there’s clay subsoil less than a mile away and in the other direction it’s nearly all peat fenland. Very mixed geology in the UK. 😆 
    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh

  • ObelixxObelixx Vendée, Western FrancePosts: 28,400
    If you have well drained soil you don't need grit.  You need organic matter from well-rotted garden compost or manure.
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • BrexiteerBrexiteer Birmingham Posts: 955
    Hostafan1 said:
    Forgive our bad manners:
    Welcome to the Forum @contact57
    You don't have bad manners hosta, Your the prime example of the perfect lady. Always respectable kind and courteous ☺☺ never nasty or sarcastic and always ready to help anyone in need. I know we had our differences in the past which are now sorted out and mended and I look forward to a great blossoming friendship for the future on the gardeners world forum x
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