How do I know if I am overwatering my Hydrangea please?

Hi,

I bought the adult plant from a garden centre late last Summer, with flowers and leaves and it seemed OK.

BUT now it is starting to grow leaves quite a few look wilted and going yellow. I have looked but can't see any 'bugs' on those leaves. I have Googled it and it mentions overwatering them, BUT I thought Hydrangeas liked lots of water, so have been watering it quite a bit

I love Hydrangeas and will be sad if I am doing something wrong? I hope there is something I can do to help it. It is a south/west shady border.

Here are some images of the plant and some of the affected leaves. Thank you in advance.

 

I don't know if your problem is specifically down to overwatering. My hydrangeas get watered only when they show signs of stress, such as wilting during a hot dry period then they get a through soak.

 

Thanks @NigelJ, I'll stop watering them just incase that helps.

 

Hydrangea roots grow like a pancake on the top 10 cms, more or less. So, here is what I do:

Do they need water? insert a finger into the surrounding soil (careful with the roots) to a depth of 10cm and water if the soil feels dry or almost dry.

Was it enough water? After watering the plant and waiting a few hours, insert a finger into the soil to a depth of 20cms and see if the soil feels dry or almost dry. If dry or almost dry, increase the amount of water or research why the water drained so well/fast (for example, do you have sandy soil which drains too well, etc).

Maintain 5-10 cms of organic mulch all around the shrub all year long (do not use rocks as mulch though). Since you do not have mulch now, soil moisture can be easily be lost on those top 10 cms where the roots grow.

Never water the leaves (to prevent fungal infections like powdery mildew or cercospora leaf spot) but water the soil from the crown (where all the stems originate from) outwards in all directions.

The leaves in the pictures: looking online at past weather in Margate, it looks like you were recently close enough to freezing to have the possibility of frost. So I am going to say the cold weather may have zapped some of the leaves. You may want to protect and to water deeply next time that there is a late frost. On this side of the pond (I am in Texas), plant nurseries collect weather and frost information that is used to calculate average dates of last frost for individual cities. For me, the average date of last frost in the first week in April. Since it is an average, I then add one or two weeks to the date and stay ready to protect hydrangeas from possible late frosts or late freezes until then. Of course, I cannot remember this every year so I add notes to my wall and electronic calendar as reminders. Ha!!!

To help the plants when there is a frost warning, I use mulch, frost cloth or blankets and I also water them deeply the night before the late frost. I have also covered them with a mountain of mulch that I then use elsewhere in the garden in mid April. Oh, and once in the last 20 years, I even had to prepare formal "winter protection" in March because temperatures were predicted to crash to -6C and the hydrangeas had already leafed out and some even had opened their flower buds and had small broccoli heads.

Mopheads tend to sometimes break dormancy too early and if you get late frosts / freezes, the leaves and or stems get hurt. But new foliage grows back in 2-4 weeks. New stems may take 4 weeks or so. And the roots, if the plant is well mulched, should be ok.

I also noticed that the leaves look awfully yellow so be on the lookout for chlorosis issues. That is when the plant cannot absorb some minerals because it rained a lot or the soil is too alkaline. Hydrangea leaves that get iron chlorosis turn light green or yellow except for the leaf veins which remain dark green. To correct chlorosis caused by alkaline soil, I amend my alkaline soil with either greensand, garden sulfur, aluminum sulfate or iron-chelated liquid compounds. The leaves will then take a darker green color after 2-3 weeks.

 

WOW @luis_pr thank you so much for all this wonderful information .

I have saved it and will check all the things you said and hopefully it will start to look more healthy soon.

Thank you again, I appreciate your time in providing this advice.

 

I was thinking chlorosis.

 

Thank you @pete

 

Thank you @ARMANDII, I hadn't thought of that. I can move it further down the border where it is in the shade most of the time, most of the year.

 

I agree with @luis_pr most of the damage looks frost damage.

 

Thank you @Cuttings, I am going to get some 'fleece' (I think that's the right thing?) when I can get to the nursery, hopefully, tomorrow and will pay attention to the nightly forecast, as @luis_pr suggests.