Grassmannian Gq(n, k) is the set of all k-dimensional subspaces of the vector space F n q . Recently, Etzion and Zhang introduced a new notion called covering Grassmannian code which can be used in network coding solutions for generalized combination networks. An α-(n, k, δ) c q covering Grassmannian code C is a subset of Gq(n, k) such that every set of α codewords of C spans a subspace of dimension at least δ + k in F n q . In this paper, we derive new upper and lower bounds on the size of covering Grassmannian codes. These bounds improve and extend the parameter range of known bounds.