Worms will catch every fish that swims, and roach are suckers for these baits. In fact, in some venues aquatic worms and midge larvae make up a large part of the diet of roach.
Chopped worm and caster is a classic combination of feed and hookbait, ideal when you want to put together a mixed bag of fish.
To be more selective for roach, try fishing half a dendrobaena over hemp. Don’t be afraid to use the largest worm that you can for roach, as this will often single out the larger specimens.