AusBonsai

Hi everyone
I planted this small cutting over a rock last winter , and up till recently it was all closed in at the top with the foil wrapped around. A pesky blackbird pulled all the foil away exposing the roots at the top , and I read somewhere on the forum that maples roots don't really fatten up once exposed . If I repot it in the winter covering all the roots would it start the roots up fattening again . Thanks in advance for any assistance
regards peterb

They should still fatten up even when they're uncovered. If the roots below are fattening and the trunk above is fattening then the roots in between will also fatten up at the same rate.
I don't normally cover the upper roots when making ROR tridents. Need to allow water into the roots ion the rock so they can grow.
Whatever you do don't cover with soil or potting mix. Tridents love to send out new roots right at soil level and they will grow right over the foil and get really strong and ruin all your work.

Thanks Shibui, that makes me feel quite relieved
Peterb