Some of the plants used in these greenhouse experiments were grown in flats and others in different sized pots. The geometric mean of the individual top-root ratios (T.-R.R.) and Pearson''s factors for the correction of the standard deviation were applied to data obtained. The T.-R.R. of lettuce (Grand Rapids forcing variety) was influenced by soil acidity, and was increased by increasing soil fertility and by short days (as against long days). The T.-R.R. of radish plants (Scarlet Globe variety) showed no response to soil fertility (CA(NO3)2) but increased as length of day was shortened. Tomato plants (John Baer variety) gave an increase of T.-R.R. with increase in size of pots and also an apparently lower ratio with pruned and deflowered plants as against the controls. The correlation co-efficients presented show a general positive correlation between tops and roots.