Tipburn of cabbage has been prevented in growth‐chamber studies by enclosing plants at night in plastic bags to encourage root pressure flow. Short‐period (4 hour) uptake studies of45Ca from nutrient solutions have shown a large accumulation of45Ca in the inner leaves when the entire plant was enclosed, so that root pressure flow occurred. However, there was essentially no accumulation of45Ca in inner leaves when only the inner leaves were enclosed and the outer leaves were exposed to an atmosphere that encouraged transpiration from these leaves. The small amount of45Ca present in these leaves accumulated in the center one‐half of the leaves and none was found in the marginal areas of the leaves. A tipburn of developing leaves of young ‘Red Core Chantenay’ carrot plants also has been prevented by enclosing the plants in plastic bags at night to encourage root‐pressure flow. This disorder of carrot leaves occurs with rapid growth in controlled‐environment chambers. Daily sprays of CaCl2solutions greatly reduced the severity of this injury.