The indirect object in the sentence "The gardener gives the garbage to the collector on Tuesday mornings and Thursday afternoons" is the collector.
An indirect object is a person or thing that receives the action of the verb indirectly. In this sentence, the gardener is giving the garbage to someone, and that someone is the collector. The garbage is the direct object, because it is the thing that is being given.
The morning and Tuesday are both adverbial phrases that tell when the garbage is given to the collector. They are not indirect objects.