GPR with a suspended 1 GHz horn antenna was deployed in the greenhouse and field for measurement of near-surface hydrologic parameters over bare and wheat canopy covered soils. Analyses of time-domain (TD) surface reflections (SR) and signal propagation times (PT) to reflective layers underlying plant canopy or a soil layer showed that SR values progressively decreased with increasing canopy biomass according to Beer-Lambert type relationships, while PT values remained unaffected. TD GPR measurements also showed the effects of soil texture on water content dynamics. Conversions of GPR reflections from TD to frequency domain (FD) showed differing dynamic responses for scattering from specific canopy and soil elements and entire profiles for varying soil types and conditions at 1.26 GHz (L-band) and 430 MHz (P-band), frequencies which are used by air- and spaceborne radar platforms. In general, L-band was more affected by surface (0-1 cm depth) soil water content conditions and vegetation than P-band, as expected. This demonstrates the usefulness of a 1 GHz center frequency horn antenna GPR for (1) characterization of vegetation canopy effects and subcanopy water content measurements within a well-defined footprint, and (2) calibration and verification of radar imagery using a single sensor.