For deployment of Wireless Sensor Network in precision farming to be successful, a study of the performance of wireless systems from a network coverage and link quality perspectives must be conducted to ensure a reliable, optimized and cost effective deployment of the network. This paper reports on sets of measurements conducted in a potential precision farming site where there are mixed types of crops which would affect signal strength and link quality of WSNs. We observed insignificant differences in signal strength between antenna heights of 0.5 m and 1m for a flat open grass field. However a significant reduction in signal strength was observed in the presence of thick vegetation on the farmland which limited coverage to only 10 m range. In addition the range of WSN coverage is also reduced to about 16 m for measurements in a greenhouse with grape trellis canopy. This is contrary to enhancements of received signal strength by lateral waves propagating along the canopy reported by other researchers [8]. The paper also provides a comparison in network coverage for the same type of vegetation in greenhouse and outdoor environment.