Many wireless sensor network applications require secure communication between nodes in the network. However, establishing pair-wise keys between nodes to provide security is challenging due to the limited resources in sensor nodes and the hostile environments in which they are deployed. Many key establishment schemes have been previously proposed for wireless sensor networks. However, most of these schemes were designed to work in a homogeneous network environment in which the nodes all have similar capabilities. Our work establishes that better performance can be achieved in a heterogeneous sensor network environment. We present a key management scheme for establishing pair-wise keys after deployment in a heterogeneous wireless sensor network. We take advantage of the more powerful nodes present in a heterogeneous network to reduce the communication overhead and ultimately the power consumption necessary to perform these services to the network. Additionally, by taking advantage of these nodes we are able to increase the overall network connectivity and resiliency against node capture attacks.