Welcome to NGA. This is an example of guttation, a process whereby hydrangeas release excess water through special structures called hydathodes. Hydrangeas are known for this, especially in humid conditions during a wet season and it is normal and typically harmless. However, if the source of this excess moisture is from soil moisture (not from the ambient humidity), water only if the soil is dry at a depth of 4 inches in several spots under the canopy. Increased air flow and morning sunlight around/inside the shrub might sometimes help reduce ambient humidity slightly in some locations.
Average relative humidity (%) in April:
Daily Place Morning Afternoon
76 Olympia 89% 57%
81 Quillayute 91% 67%
71 Seattle 82% 57%
In this table of three western WA cities, the Daily column's number is the daily average number of humidity readings taken about every three hours throughout the day since the start of April. Morning percentages are for 7 am and Afternoon measurements are for 4 pm, local standard time. The western Washington area tends to have the highest average relative humidity between 4am and 7am. A relative humidity measurement above 60% is considered to be high.
As the seasons change and summer-like conditions arrive, you will cease to see guttation. Western Washington typically experiences a dry season from late June to early September, resulting in relatively low humidity and little precipitation during this time.
