Diagnosis please...Disease, Stress, Sunburn...What???

This is a lovely Shooting Star (aka Fuji Waterfall) hydrangea that I received this summer. Yes, it was a forced bloom florist plant, but I cut it back, repotted it and it grew nicely on a shaded porch from mid summer till October. Brought it in the house about a month ago prior to any cold weather below about 55 degrees. Now it's leaves look like this, though the plant itself seems pretty healthy and is putting out new growth. It is in a South facing window where it does receive some direct sun for about an hour each day, and bright light the rest of the time. The spots developed fairly quickly (over a week or two) and are present on leaves on all parts of the plant, with the exception of those just coming out. No difference between leaves near the soil and those near the top of the plant--some of all are affected. Any ideas? My only thought is maybe sunburn as the plant had never had direct sun, and maybe even a short period of direct winter sun was too strong? No other plant is affected (this is the only hydrangea overwintering in the house--others are geraniums and coleus). Help--I love this plant!

I'm not sure if you really have a problem--I'm not sure what happens if you keep them indoors, but outdoors even in warmish climates they're deciduous, so the leaves could just be getting ready to fall off. Some varieties will get nice fall color if you had the right conditions, but I've had leaves just get ugly looking and then fall off. I guess it could be sunburn too, it doesn't sound like it's getting a ton of sun but if it was getting none before and now it's getting some that could be it--if that's what's going on then you should put it in a different window and the problem should stop getting worse. I don't know what zone you're in, but I'm guessing about zone 7? If so, you should be able to plant it in the ground and keep it out there year-round and it may end up being happier there in the long run (I had a Shooting Star that I kept as a potted plant for a while, but it was much happier when I planted it in the garden).

Thanks Ecrane3--You know, I hadn't really considered the possibility that this was just seasonal leaf shed. I presumed that I could overwinter it since it was greenhouse raised, then put it in the ground and let it resume a more normal "life." It can go outside here, and that is my intent, but I didn't put it out this year because I didn't feel it would be hardy enough yet. You might have the answer...I'll have to wait and see. Does anyone know if it is temp, daylight hours or what that drives hydrangeas' leaf shedding/dormancy. Any experts out there?

For plants that are strictly deciduous, I think it's triggered by day length, otherwise nothing would ever lose its leaves in warmer zones and we have plenty of deciduous trees out here that lose their leaves each year just like they would anywhere else (lack of cold sometimes leads to a poorer display of fall color than you might have in other parts of the country though!). There are some plants that are evergreen in warm climates but will become deciduous in cold, those are triggered more by temperature but I don't believe hydrangeas are one of those.

I see you are in Dublin--I used to live in Alameda--can't remember what my hydrangeas did there. I think they hung unto their leaves until about January, then resprouted in April. I'm still not 100% convinced its just leaf drop though, as I just checked the hydrangeas outdoors here and--guess what--they still have all their leaves! Hmmm...the mystery deepens.....

A few of mine here have dropped their leaves, some still have them (my Shooting Star is one of the ones that has dropped them), I think a lot may depend on the particular species/cultivar. And like I said in my first reply, if they were getting no direct sun at all before and now they are, it could be sunburn, you could try moving them to a less sunny window and see if the problem stops getting worse (existing damage won't reverse itself, but you should notice no new damage)

yote dog? any update on your hydrangea spots?
stephanie

Well, I removed all the affected leaves, which left it pretty bare. It is putting out new growth, but some of the older leaves keep showing the spotting, then I remove them. Overall, I'm leaning towards the theory that the plant was stressed for two reasons--the change from outdoors to indoors, plus it hasn't had a chance to go dormant. What I can't figure out is why the leaves continue to develop the circular yellow ( then brown and dead ) patches. To me, that doesn't fit with either stress, sunburn or simple leaf shedding due to "season" confusion. The plant is now quite bare, but as I said, putting out new growth, so seems healthy overall. Any ideas?

I have a book that helps diagnose plant symptoms, and the only think it lists for hydrangeas that matches your yellow spots are a couple of leaf spot fungi so that would be my guess. The book says they're spread by air and splashing water, and favored by prolonged cool, wet conditions. I would remove any fallen leaves, and remove infected leaves as you see them, and be really careful when you're watering that none of the water splashes up onto the leaves. It might also not be a bad idea to repot it into some fresh clean potting soil because there are probably fungal spores in the soil that are getting splashed up onto the leaves when you water. You could spray the leaves with an antifungal if you wanted, but I would only do that if you do all these other things too, if you don't get rid of the cause of the fungus (stuff in the soil that gets splashed on the leaves), the antifungal spray won't fix the problem by itself.

You know, whenever I see "circular spots" I, too, think fungal. I'm just perplexed as to the timing as you would think this would have happened outdoors (high humidity) not indoors. Maybe it was just developing as I brought it in, coincidentally. I will spray it with some organic antifungal stuff I have (I think its rosemary oil) or maybe some baking soda solution and we'll see what happens. It has not been subject to much splash since coming indoors, but definitely was outdoors (my child "helps" me water...!). I'll report back in a few months as we see what its doing. Thanks!

I bet it did start when the plant was outdoors, as long as you're not seeing spots develop on the newer leaves then you may be OK, but I would be really careful about splashing water until you're sure it's totally gone. Changing the soil still might not be a bad idea, fungal spores can survive a long time so the problem could easily come back when you put it out in the spring and your "helper" starts watering it again!

Yes, I think you are right. I will definitely repot it and maybe put it out of reach of my beloved gardening "assistant"!