Allotments 4 All

I've found lots of coloured glass pebbly things and fancy decorating some terracotta pots with them,something to do in the shed after Christmas .
Can anyone suggest the best thing to stick them on with ?Bearing in mind they'll be outdoors in all weathers and they are quite heavy ???

i think i've seen them use tile grout on the tv for this :)

We put them on with no nails to hold them in place, then grout them with a tinted waterproof elastic grout. The 'ELASTIC' in the grout moves when the sunshine or the frosts hits the pots,walls or objects we do like this

 Some ones got a lot of patience.  Thanks for sharing Ace.