In article ,
says...
Tonight, Tony Buckland was using horticultural grit on the top of some pots
of bulbs. What is the difference between this grit and any other
grit/gravel?

Generally its grit that has been washed and graded to remove any clays
etc and is lime free, if like me you live in an area where the china clay
waste is used also for the building trades then there is no difference!
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea