By Mowerman
East Sussex coast,
United Kingdom 
Hydrangea problem.
I bought a Hydrangea Runaway Bride last Autumn – it’s a recent newcomer. Around mid February the leaves started to appear and by mid March had grown a tad over half an inch long with flower buds just beginning to appear – and there they stopped and haven’t grown any further since. The edges of the leaves are very slightly scorched although the plant has been kept watered and in dappled shade. We’re on the coast and haven’t had any frosts this year. Any ideas as to why it’s stopped growing ? Thanks.
Roy
23 Apr, 2019
Answers
It does look like the plant is detached/not rooting in the compost/soil. Bit greyish looking soil on top?
Saying that I’m no expert! Just a hobbyist. I’m sure the others will help greatly.
24 Apr, 2019
Thanks Tugbrethil
In answer to your questions:
50:50 JI No 3 and multi compost.
Yes
Kept moist at all times.
Half strength liquid tomorite fertiliser fortnightly(+Micro risal fungi around roots when repotted.)
No as it was semi rootbound.
Roy
24 Apr, 2019
This happened the other year with one of my clients, she has a few hydrangeas in pots, two of them came into leaf,quite well, then suddenly lacked vigour and the growth seemed stunted, my initial thought was vine weval and so it proved, having lifted them out, many vine weval grubs had been munching enthusiastically through the roots, the root system I thoroughly washed and replaced in decent compost yes they looked poor for some time but eventually perked up, it may not be the case for yours but worth checking.
24 Apr, 2019
Hi, when you repotted this, did you untangle the pot bound root a little ?, this looks as if the roots are still going round and round in the old compost, so the water you've been giving it, hasn't got through to the roots, otherwise if you've been feeding it, and it's in fresh compost, it shouldn't need feeding yet, so it could be overfed, other than these possibilities, it could be as Julien has suggested, Derek.
27 Apr, 2019
I think the pot is too small - The Hydrangea will overheat in the summer & freeze in the winter. The damaged roots cannot support the top. Hydrangeas should be planted in the ground so they can take up sufficient water & nutrients to complete it's growth cycle. This one ran out of 'gas'.
27 Apr, 2019
Previous question
« Where is Little Joe? I picked up a couple 'Joe Pye Weed' (Little Joe) plants...
Kind of scary looking potting compost, And it looks like it is drawing away from the sides of the pot--a sign of drought. To find out what is going on, we'll need the following info:
What kind of compost is it in?
Does the pot have a drainage hole?
How much and how often is it getting watered?
Is it getting fed, and, if so, with what?
Did a lot of compost fall off the roots when it was taken out of the original container?
24 Apr, 2019