Exposure of ginger rhizome seedpieces to 35°C for 24 h or to 250 p.p.m. 2-chloroethyl phosphonic acid for 15 min. caused substantial increases in shoot and growth during the first 23 days of growth. Of the two treatments 2-chloroethyl phosphonic acid was the more effective increasing the number of roots per seedpiece by a factor of 4·0 and the number of shoots having roots by a factor or 3·7 (both at day 16). Relatively low concentrations of 2-chloroethyl phosphonic acid (less than 250 p.p.m.) were sufficient to produce maximum responses in terms of shoot length parameters but significant increases in the number of shoots per seedpiece, the number of rooted shoots and the total number and length of roots per seedpiece occurred up to the highest concentration studied (1000 p.p.m.). Treatment with 2-chloroethyl phosphonic acid was effective in reducing variability in root growth but shoot growth variability was increased particularly at concentrations below 500 p.p.m.