The garden, overall, is representative of growth, maturity, and development for the characters at large. However, for Gonzalo in particular, it represents responsibility as well. He has many things for which he must take care, being the most proficient in English of his entire family. He must translate and help lead his family in spite of being so young and inexperienced in the world. In the same way, his work in the garden is a responsibility, and for quite some time he feels like he is carrying a load on his shoulders that is not his to bear.
However, he eventually begins to grow in his understanding and care, and in particular he grows in terms of his attitude towards his uncle. As his uncle helps him in the garden, he realizes that the older man is very experienced, wise, and successful, even if it is not in ways that were initially evident to Gonzalo. By seeing his expertise in the garden, Gonzalo learns to respect his family more and grows into a better, more mature individual.