This is the 1192nd most frequent Catalan word.
superior
Higher; superior; upper.
In this sentence, 'superior' is used as an adjective meaning 'upper' or 'top part of' to describe the highest section of something spatially, in this case, a garden.
Aquestes plantes creixen millor a la part superior del jardí.
These plants grow better at the top part of the garden.
Here, 'superior' denotes a comparative quality, meaning better or higher in status, rank, or quality.
Les seves qualificacions són superiors a les de la mitjana de la classe.
His grades are superior to the class average.
In this case, 'superior' again refers to the physical upper section of an object, indicating spatial characteristics.