Thanks Lyn and Dove from above. The helpful people above have calculated how much I need (14/15 bags) so I'll use that amount of my own and remove last years which sits above 12 inches of earth.
Don't waste time removing it. Just pile the new stuff on top and keep all the microbes and other organisms in the old stuff. It'll all work itself together over time.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
Obelixx: Comment acknowledged but... the soil is contained away from the flooring (see photo) so I need to maintain that level. Last year's home made compost was hand crumbled to dust then mixed with 30% perlite. I plan to remove and rinse about 4 inches separating the perlite with a fine sieve. The water can be bottled and added next year, hopefully still containing some nutrients from the sludge. I have 300 litres of new stuff already waiting to mix with the old perlite next April.
Sieving out the perlite doesn't sound much fun. If your bed requires ~300 litres total, you can buy 100L perlite for £20. It's a big bag, but weighs almost nothing. I change the soil in the tomato border in my g/h every 2-3 years to a depth of 1 spade. I refill with a 50/50 mix of topsoil and rotted manure/compost.
Billericay - Essex
Knowledge is knowing that a tomato is a fruit. Wisdom is not putting it in a fruit salad.
Obelixx: The 8 x 10" pots sit on the central tables not on the soil (32 varieties of toms this year in all). If there's no nutrients left from last year's compost then I agree it would be easier to buy new perlite, you tell me is it worth sieving?
Pete8: the 300/350 litres of new compost would be added to perlite for drainage. I thought of adding an extra 100 litres of fine pine bark as well might be a good idea, what do you think? (There will be enough space to use 500/600 total new mix).
I think I have lost the plot here! Are the beds really only 3 inches deep and what are they used for? Is it only for standing pots on or do you plant into them?? I am sorely confused now.
'Optimism is the faith that leads to achievement' - Helen Keller
Pete8: the 300/350 litres of new compost would be added to perlite for drainage. I thought of adding an extra 100 litres of fine pine bark as well might be a good idea, what do you think? (There will be enough space to use 500/600 total new mix).
I've never used fine pine bark, so don't know if it's a good idea. I do know it can be quite acidic though. I use rotted compost/manure mix and topsoil from the garden which I replace with what I dig out of the greenhouse.
Generally I start afresh every 2-3 years in the tomato border for the same reason as crops are rotated - to stop a build-up of nasties
I know you like to grow different varieties and another forum member mentioned this site a while ago. A bewildering choice... I'm going to try Rose de Berne next year.
hogweed: The builders poured concrete over the breeze blocks in the trench levelling it (around the sides), 14 courses of bricks were built on top, 3 courses have topsoil, above 2 courses have fresh compost replaced each year - apparently up to 600 litres. Total growing depth 16 inches. The 8 pots are on staging in the centre of the floor.
Pete8: I'll add the fine pine bark, thanks. After mixed success with those 32 varieties I'll stick to half a dozen this year. As mentioned in my previous post I let the Super Sweet 100 grow without removing any side shoots and one plant produced over 600 tomatoes. Overall, the black/brown cherry varieties were the sweetest but the thin skins split when ripe rather than being easy to twist off.
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P.S. We stayed at Champ-Saint-Pere, lovely.
If your bed requires ~300 litres total, you can buy 100L perlite for £20. It's a big bag, but weighs almost nothing.
I change the soil in the tomato border in my g/h every 2-3 years to a depth of 1 spade.
I refill with a 50/50 mix of topsoil and rotted manure/compost.
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
Pete8: the 300/350 litres of new compost would be added to perlite for drainage. I thought of adding an extra 100 litres of fine pine bark as well might be a good idea, what do you think? (There will be enough space to use 500/600 total new mix).
I've never used fine pine bark, so don't know if it's a good idea.
I do know it can be quite acidic though.
I use rotted compost/manure mix and topsoil from the garden which I replace with what I dig out of the greenhouse.
Generally I start afresh every 2-3 years in the tomato border for the same reason as crops are rotated - to stop a build-up of nasties
I know you like to grow different varieties and another forum member mentioned this site a while ago. A bewildering choice... I'm going to try Rose de Berne next year.
https://www.simpsonsseeds.co.uk/acatalog/Tomatoes.html
PS - have just read that toms prefer a soil pH of around 6.0-6.8 so maybe pine bark fines are a good idea
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
Pete8: I'll add the fine pine bark, thanks. After mixed success with those 32 varieties I'll stick to half a dozen this year. As mentioned in my previous post I let the Super Sweet 100 grow without removing any side shoots and one plant produced over 600 tomatoes. Overall, the black/brown cherry varieties were the sweetest but the thin skins split when ripe rather than being easy to twist off.