Seedlings of 4 coniferous species, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), white spruce (Picea glauca (Moench) Voss) and lodgepole pine (Pinus contorta Dougl.), were grown for 4 mo. from germination and were then exposed to soil drying. Rates of photosynthesis were measured for all species and rates of dark respiration and transpiration were measured for Douglas-fir and hemlock. In a study of survival, seedlings were exposed to various durations of soil drying and the plant water potential was determined before the plants were rewatered; seedling survival was subsequently recorded. Rates of photosynthesis declined for Douglas-fir, hemlock, spruce and pine when the plant water potential decreased from -10.0, -10.7, -12.4 and -6.6 bars (1 bar = 100 kPa), respectively, and became zero with potentials of -53.9, -39.7, -28.6 and -22.4 bars. When grown together in the same pot and exposed to soil drought, hemlock had a consistently lower potential than Douglas-fir and spruce had a lower potential than pine. Hemlock could survive potentials of -40 to -60 bars, whereas seedlings of the other species survived potentials to -110 bars. [This research has application for seedling survival in forestry plantations during summer drought.].