Forum home Garden design

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: 25,386
    basically it's any " stone" crushed to a certain size. ( same size as perlite / vermiculite ) a few mm in size.
  • FairygirlFairygirl west central ScotlandPosts: 31,104
    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: 20,588
    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: 5,707
    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: 15,977
    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: 25,386
    Forgive our bad manners:
    Welcome to the Forum @contact57
  • Depends what you want to use it for.
    Perlite can be used to mix with your potting compost and helps it to become free draining.
    Vermiculite can be used to mix with a medium if, for eg, you want to sow seeds.  It can also act as a "topping" for your seeds.
    Both the above are lightweight and no good for garden borders as such -just pots and containers.
    Grit can come in various forms - usually small and sharp.  Mixed with compost, it provides a free draining medium.  Can also be used to top dress various potted plants.  In quantities, it can also be used in conjunction with various other materials if, say, you needed to improve a heavy soil.
    Sharp sand can also be used in much the same way as grit.
    Don't know whether this is of any help.
  • 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?  
  • Not sure that England has mainly clay soil.

    If you already have well drained soil, why not just go with that for your raised beds?  It does depend what you intend to grow in the beds, depth, etc. as to the soil makeup - horses for courses as they say.

    No idea about basalt I'm afraid.  Have you tried checking out gardening sites for your particular area of the US - that may offer you a bit more of an idea.  Better still, what grows well in your immediate vicinity in the same soil type.

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 61,588
    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

Sign In or Register to comment.