What's the point of seed starting compost/potting mix?

[Two_Sheds]

I use MCP for everything

me too

seed starting compost is also usually sterilized

all potting composts should be sterilised, so that weed seeds won't be in it

I've been using sieved grow bag contents

me too, perhaps with a little BFB or wood-ash added, if I have any

Charle's Dowding's ...says that it's OK to sow seeds directly into straight compost ..

do you mean potting (shop) compost, or garden (homemade) compost? The latter is going to be full of weed seeds most likely

[danmow]

Hi Two-Sheds...no I mean homemade compost. Won't the high temperatures in the heap kill any weed seeds?

[WendyC]

Most don't really get hot enough, for long enough. I know this to be true of the compost I tipped out of one of my allotment bins a few weeks ago when I needed the bin. It is now sporting a lovely green thatch of chickweed!

[Penellype]

Some seeds are tougher than others. I shove everything in my hotbin and it seems to kill most of them, but the tomato seeds seem to survive as I had loads of tomato seedlings sprouting in my potato buckets this year.