Plug plants/Jiffy 7s

I received some plug plants by post today, they are ivy leaf geranium, the plants look ok, I know that you are supposed to plant them in there retaining net, and with the ones I got today the retainer looked like a bit of fleece like material, in the past I had planted them as directed but at the end of the season most of the roots were still retained in the net so I now remove the net before planting, now thinking I should have left a couple to see if what is used nowadays rots away, also wondering what others do