Hydrangea lower leaves turning yellow (photos) why?

[millefeuille2]

My relatively new (planted into the ground a few months ago) hydrangea's lower leaves are turning pale yellow. I've been careful to water it during the heatwave. Our soil is clay, and is covered in bark chips.

The internet says it's either overwatering, iron deficiency or too much sunlight. Which do you think it is? The leaves are yellow to the point of being white in some cases. They're not soft or mushy. I can't see any visible pests.

Help!

Probably just because it’s almost autumn.

Not sure - it may be that they're in the shade, so not doing much for the plant so it's in the process of shedding them. In which case nothing to worry about.

I think iron deficiency wouldn't just affect the lower leaves and would give a veining pattern. It's not likely to be too much sunlight affecting lower rather than exposed leaves. And I've never heard of a hydrangea minding a lot of water.

We only moved in last autumn so I haven't yet been through a full annual cycle! Do hydrangeas lose their leaves around now?

It's true they're below lots of other leaves and not doing much. I'm relieved it's not nutrient deficiency!

They don’t lose leaves yet but they do tend to start to change colour - plus the hot dry summer will speed up autumn for all plants.

A few of my plants have done the same. I think it's a case of roasted roots in the hot weather. Were the pots in full sun?

I've sunk my pots in some gravel and made sure they don't get too hot. Both plastic and terracotta can really cook.

Thanks for the replies all. To clarify, they're not in pots. They're in the ground, in partial shade.