I have an hortensia which is getting more and more brown leaves (see pictures)
Ground seems OK (not dry). Any idea on a possible cause?
I am using tap water as I did for years, the same I use for all the other plants.
This are the moisture level measured with Parrot Flower Power (I have no previous values due to a strange bug):
The vase has some gravel on the bottom and a hole at the bottom.
I added some fertiliser one week ago (a specific product for hortensiae from Gesal: 7% Nitrogen, 3% Phosphorus pentoxide, 5% Potassium oxide, 0,01% B; 0,002% Cu*; 0,05% Fe*; 0,02% Mn*; 0,001% Mo; 0,002% Zn*)
The leaves began to turn brown a couple of weeks ago but in the last few days it seems that it is accelerating.