What percentage of grit do I add to my own ready compost for Tomato plants next Spring?


  • Hostafan1Hostafan1 Posts: 14,136

    that would depend upon the texture of your compost. 

    I've never added grit to tomato plants, only those plants which need sharp drainage.

  • BerghillBerghill Posts: 2,805

    Tomatoes do not need grit in the compost.

  • Hostafan:  I've hand sifted 600 litres.  At the moment it's a cross between sand and cooked mincemeat texture.

  • Berghill:  As the texture is so fine surely it needs some aeration/drainage to stop it compacting?

  • Pete8Pete8 Posts: 2,831

    If it's for use in pots, the perlite would open-up the texture and help with drainage


    I bought this last autmun - the bag is HUGE!

  • Pete8:  Perlite is good but does it disintegrate in time (I'm thinking enviorementally?)

  • Hostafan1Hostafan1 Posts: 14,136

    given that tomatoes seed everywhere in my sodden, clay soil, whenever I spread compost, I'd assume they're not overly fussy.

    Personally, I'd not waste my money on grit ,or perlite for tomatoes.

  • Pete8Pete8 Posts: 2,831

    Perlite (volcanic rock) and vermiculite (silica) are both natural products.
    Vermiculite won't last more than a season, perlite should be ok for 2-3 seasons.
    I always use perlite for pots (it's very good used alone for cuttings) - it weighs almost nothing and does a good job.
    I only use grit in open ground

  • BerghillBerghill Posts: 2,805

    If the compost is as fine as you say then you would be better adding some larger particles of humus(not the word I am looking for, but my brain is still asleep) rather than grit or perlite or vermiculite. Sounds to me like you may have put it through too fine a riddle.

    We grow our tomatoes in unsifted compost from the compost heap. They grow well.

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 42,728

    I think it sounds as if Berghill is right and the compost has been riddled too fine.  In that case I think I'd buy some peat-free multipurpose compost and mix it in with your fine garden compost at a ration of about half and half ... tomatoes should be happy with that. 

    Last edited: 31 December 2017 11:12:14

    A society grows great when old men plant trees whose shade they know they shall never sit in - Greek proverb 
  • PalaisglidePalaisglide Posts: 3,136

    My Father grew tomato's all his life in ordinary garden soil, he would mix in some of the Compost from the midden mainly horse manure and straw rotted down well. I have also grown tomato's all my life using bought compost mixed with my own compost and never equalled the harvest Dad used to get.

    My best results are with bottomless pots on a gravel bed which I keep damp at all times, tomato's send down tap roots into the gravel and the damp air rising from the gravel during the heat of day appears to help. I never mixed grit of any kind in the potting mix but do start by half filling the pots then topping up with more compost every couple of weeks once the first fruit is set, it works for me.


  • Sorry, I didn't know Perlite was natural, it was this stuff made from tiny polysyrene balls I wanted to avoid.  The only problem when using Perlite previously in the greenhouse floor was that when the watering puddled it tended to collect on the top.

  • BerghillBerghill Posts: 2,805

    Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is however  a non-renewable resource.

  • Thanks everyone for your helpful comments.

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