My garden plants—especially cucumbers and certain types of weeds—often exhibit a row of water beads in neat, uniform rows on the surface or edges of their leaves early in the morning. This phenomenon, lovely as it is, goes by the unfortunate name of guttation.
Guttation is not the same as dew. Dew forms on the surface of leaves and grasses when moisture in the air condenses into little pools of water. Guttation occurs when water pressure inside the plant pushes water out through water glands called hydathodes. This is most likely to occur on cool nights or when high humidity inhibits natural evaporation of moisture from the leaves. Roots continue to draw water from the soil, and when internal water pressure becomes too high, it forces excess moisture out through the glands.
Guttation is not an indication of over-watering. Rather, it’s the reaction of a healthy plant. Over-fertilizing, however, can have a negative effect via guttation, because of minerals that may be carried out onto the leaf tips and left there to accumulate when the water dries.
The origin of the word is from the Latin “gutta” meaning “drop.”