‘Forest Green’ parsley ( Petroselinum crispum L.) seeds were leached for 3 days in aerated water at 25°C and then primed in aerated polyethylene glycol (PEG) 8000 solutions for 4.5 days at 25°. Priming improved earliness of germination at all temperatures of the tests (5°, 15°, 20°, and 25°), with the largest improvement at the coolest temperature. Uniformity of germination, as measured by the mean time between 25% and 75% germination, was not significantly affected by priming. Primed seeds germinated significantly faster than unprimed seeds when water stress was applied by low osmotic potentials (PEG solutions, -0.25, -0.5, or -0.75 MPa, were substituted for water). The latter result supports the hypothesis that priming induces the development of low cellular osmotic potentials. The priming effect was not lost during 8 months of storage, indicating a good treatment longevity.