50#, if you are using to top seed pots, is going to last you a VERY long time :) My local farm store sells by the pound, my choice of how much.

And where many of my containers are open to the weather (which may well be location specific to my climate), it keeps the seeds from being moved around by a gully washer rain :) I don't know how important in other parts of the country but I find grit helpful in mine.

Several years back I used to sow some kiddie pools each winter. It was a big do to get them filled with soil, sometimes it was a somewhat chippy mix, slightly barky. The soil would filter itself with the heavier particles moving down and the barky flakes rising to the top. When it all started to germinate most of the time the seedlings would push up the barky flakes, but some of them were hunks not flakes and needed to be lightly swept away with my fingers. I can see how a top dressing of grit might help in keeping things in place.

Karen

As an amendment to potting soil as you're repotting house plants.

Mixed into birdseed for your winter birdfeeders--the real commercial intent is to help poultry "grind" corn and seed material into palatable nutrients.

For those of you with farm neighbors who have poultry--you can often ask for a scoopful for nothing. Poultry owners generally have it on hand. Saves $$ buying it for a gardening purpose.

Do I still need to cover with soil too? I guess a little bit.
Thank you Gardenweed for your photo illustration makes it so much easier to visualize. My grit looks a little more coarse than yours, the store said it was the one used for chicks (the smallest they had) so I bought it. It costed 9 dollars. If I asked them to split it into 25lbs they only took off aobut a buck and a quarter, so bought the whole lot.

I do like all the benefits mentioned by morz8

Well here goes nothing
going to sow my first container today,
a bit nervous.
On how much soil to cover seeds with,
I'll probably cover with aobut 1/8 of finely ground soil and a tsp of grit.
Micki