Vermiculilte keeps the compost more open and allows better root formation, it also "dilutes" the compost a bit as some seeds will not germinate if there is too much nutrient in the compost. I often add a handful or two of silver sand to MPC for seeds, serves the same purpose but not as open as vermiculite.
No idea if there is any advantage/logic to this but I use fine seed compost for teeny weeny seeds but happily use Lyn’s method for big seeds like sunflowers, courgettes etc.
Nollie you could be being a little decadent. I do something similar. If I'm sowing seeds for the window sill propagator or sowing with the intention of keeping plants indoors before hardening off, a small 10 ltr bag of seed compost sits nicely in a kitchen cupboard along with a tub of vermiculite.
However if I'm sowing seeds in pots on the allotment to germinate in the GH, it's multi compost, you get more for your money and I've found the germination rate is similar.
I'll just be placing mine on south facing windowsill above radiator. Yesterday I bought a bag of vermiculite to mix in with multipurpose compost. Never sown any seeds before, wish me luck😬
Nothing wrong with a bit of decadence zoomer! Last year I found a French ‘fortified’ seed compost and was amazed by the difference - much faster, higher germination of my teeny weenies and really healthy plantlets resulted - far better than using a local brand, so have gone french again this year. Without doing a comparative trial with this and MPC I wouldnt know if its really miracle stuff or last years performance was just a blip...
Hi @floralies, it was Jardiland’s own brand seed compost - of course it could have been the case that the spanish brand I used the year before was just rubbish, hence noticing a difference!
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Nollie you could be being a little decadent. I do something similar. If I'm sowing seeds for the window sill propagator or sowing with the intention of keeping plants indoors before hardening off, a small 10 ltr bag of seed compost sits nicely in a kitchen cupboard along with a tub of vermiculite.
However if I'm sowing seeds in pots on the allotment to germinate in the GH, it's multi compost, you get more for your money and I've found the germination rate is similar.
Nothing wrong with a bit of decadence zoomer! Last year I found a French ‘fortified’ seed compost and was amazed by the difference - much faster, higher germination of my teeny weenies and really healthy plantlets resulted - far better than using a local brand, so have gone french again this year. Without doing a comparative trial with this and MPC I wouldnt know if its really miracle stuff or last years performance was just a blip...