My hydrangeas were doing well until a couple of days ago when I noticed they are losing leaves. I'm not seeing insects, but something is definitely not right. Any suggestions from the experts? I'm not sure how to post the pictures I took. First timer. . .
The hydrangea leaves are starting to turn brown in spots and then drop. A lot of the leaves on the ground still look fairly healthy and green, but some are curling up and dropping. Way more leaves on the ground than there should be this time of year.
Try to maintain the soil as constantly moist as you can. Periods of dry followed by wet are not good and can make the leaves turn brown starting at the edges. But they normally should not fall down while still green. They may stay green and crumble if they loose moisture thru the leaves faster than it can be replaced thru the roots.
Another thing to keep an eye is powdery mildew; the leaves appear as if they have some talc powder and can turn brown/purplish/etc and fall.
Curling may be caused by one of many pests that can hide during the daytime. Look for aphids, hydrangea leaf curler, borers, etc. You have to look during the day and at night.
Last suggestion to consider... have you recently applied any chemical products nearby that the shrub is reacting against? Fungicides? Insecticides?
Discard plant debris in the trash in case you have a fungal infection or disease. You can also mail a leaf sample to your Agriculture Extension Sewrvice for analysis using a clear plastic sealed bag.
I was given a nice plant as a thankyou after a lecture I did last year 2013. It did well until the sun got too hot and the leaves on the hot side got very bad die back - however, I also grow fuchsias and every now and then they get a bit of green fly so, I get the pyrethrum out and act like a GI spreading agent orange in Nam. The Hydrangea also got a squirt and, I am guessing, that it was more the spray than the sun because the flowers took a beating too. Sun, rain, shine, are all natural, but pyrethrum in heavy doses is obviously the one I'm looking at as being the bad guy in this instance.