Adding grit to soil mix

Hi everyone, sorry daft question I know but I just want make sure, when making spil or potting mixes you do add grit by volume and not by weight, i.e. using a litre pot, 1 x 1 x 1 would be 1 of whatever x 1 of whatever x 1 of grit, I'm going to add some bags of grit to an order and i want to have a weight to volume guide for future reference.

 

cant help, I'm afraid, I just chuck it in till it looks right for whatever it is I'm growing.
Never thought it was an exact science.

 

@mazambo If your soil is heavy clay like mine, you can never have enough grit, mate!

Nick

 

I find sharp sand is good for opening up composts, sometimes better than grit.

 

@pete that's really interesting, I've tried sharp sand with a little grit with an agastache in my soil and it was really successful, the plant thrived. Think I'll use plenty with an eryngium I'm planting tomorrow and see what happens.

Nick

 

In the process of opening up where my pond was to make a flower bed (albeit very very slowly) by the time gravel, concrete and fibreglass are removed there will be a lot of soil to be put in and gives me a good opportunity to make a soil to suit, hence the question.

 

Nick, with sharp sand you get particles of varying sizes, unlike graded grit.
I just find it mixes in better and does a better job than grit alone.

And its cheaper

 

And the question could apply to sand too.

 

@pete Yeah, I think I misjudged it because mixed with my heavy clay it turns into what seems like a cloggy mess to the eye, but despite my impressions it seems to be really effective with plants that favour sandy soil.

Nick

 

When mixing for pots I usually use one bag of MP 75 litres, one of sharp sand 25 kg and one of JI.

Put it all in the cement mixer.

Dont add cement

 

I think it is simpler to work by volume, assuming that you are not varying the way you measure the compost ie not compressing it. I tend to add sharp sand to all MPC because I find it gets quite claggy. I will also add bigger grit as well if I feel extra drainage required.

 

I bought sharp sand as it was cheaper. I found a pallet full of split bags which were heavily reduced. Bonus.

G.

 

Thanks @CarolineL volume it is.

 

When I've watched gardeners world, Monty Don has always premixed a wheelbarrow full of whatever. I want to mix some compost and sand ready for the children to pot up some lavender and spring bulbs but I don't want any left over if I can help it. I guess I'm going to have to measure the capacity of my pots and then work from that.

G.

 

My pots are 35cm sq by approximately the same deep. According to an online calculator, the volume of the pot is 42875.

What does that mean? How much compost is that?

G.