They sleep for a LOONG time so waking them up every time to eat is bad. Cucumber is mostly water so not good for nutrition. Maybe try putting lettuce out for a while and when he gets hungry he'll eat it.
Is Zoo Med natural grassland tortoise food similar to Mazuri? I've heard good things about mazuri and how it can put on weight fast if given too much so I was wondering if Zoo Med natural grassland tortoise food is similar.