Background and aimsThe implications of dew formation on plants have been a matter of a long research. Commonly, it is assumed that the same amount of dew is formed on both sides of the leaf (the adaxial and abaxial) and that the total amount depends on the plant density, as denotes by the leaf area index (LAI).MethodsHypothesizing that the above assumptions are incorrect, and that the sky view factor may largely determine the amount of non-rainfall water (NRW) such as dew and vapor, periodic dew and temperature measurements were conducted in the Negev Desert on plants and cloths that mimicked plant leaves.ResultsOur findings indicate that (a) the abaxial side of the leaf receives about half the amount obtained at the adaxial side, (b) shading and partial shading increase the nocturnal temperatures of leaves, largely reducing the amount of dew, (c) the assumption that LAI substantially increases the amount of dew was critically examined.ConclusionsThe common practice during which an arithmetic mean of all non-rainfall water that accumulate on the leaves is calculated is incorrect, as it may also include vapor that did not undergo condensation. Published data should therefore be carefully evaluated as they may be many-fold higher than the actual amounts formed on plants. The contribution of dew to desert shrubs should be re-assessed.