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


that would depend upon the texture of your compost. 

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


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?


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


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.


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


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.


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

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.


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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