Antitranspirant application to sweet corn (Zea mays L. var saccharata Sturt.) may be a feasible method of extending the cultivation of the crop to the dry season in Trinidad and Tobago. The objective of this study was to determine the effect of different rates and frequencies of application of phenylmercuric acetate (PMA) and Vapor Gard (poly-l-p-menthen-8-9-diyl) on the growth and yield of sweet corn grown under dry house conditions. Two experiments were carried out using potted plants growing in a mixture of soil, sand and organic matter (2:1:1). In Experiment the treatments, PMA at 15, 20 and 25 mg I-1 a.i. and Vapor Gard at 3.0, 6.0 and 12% a.i. were applied at 38 days after planting (DAP) and thereafter at 10-day intervals. In Experiment 2, PMA at 20 mg I-1 a.i. and Vapor Gard at 6.0% a.i. were each applied at 38 DAP and thereafter at 10- or 20-day intervals; or, alternatively, single applications of PMA or Vapor Gard were applied at 38, 48, 58 or 68 DAP. The optimum application rates of PMA and Vapor Gard were found to be 20 mg I-1 and 6.0%, respectively. Single applications of PMA and Vapor Gard remained effective for 20 and 40 days, respectively. Consequently, application of PMA at 20 mg I-1 at 20-day intervals, starting at 38 DAP, or a single application of Vapor Gard at 38 DAP were adequate for near maximal improvement in plant water status and increased plant growth and yield in sweet corn.