Struggling Japanese anemone

[Agapornis]

I've had this Japanese anemone for two or three years but it very quickly gets unhappy and hasn't properly flowered since I bought it in flower. It was doing well for a few weeks in March/April, but now it's getting crispy leaves again. It had a friend but that died.

It's in a planter (50 cm deep, 50x160 wide) with lemon balm, fox gloves and clematis, so generally well watered and it gets some sun around 4-6pm. I was under the impression these plants are supposed to be happy in semi shade and moist, well draining soil. What am I getting wrong?

Photo

Lemon balm can be a bit of a thug, is it getting swamped? Or could it be vine weevil getting the roots?

When ever i've had JA they've always thrived without me doing anything much to them at all - nearly always in quite dry soil ...

It takes a very special kind of skill to kill a Japanese anemone, please come and reduce mine!

Is it one of the fancy "Swan" ones? They can be a bit more fussy I believe. That or they do like to root very very deep and it may be there isn't enough depth for them to be happy.

It's a bog standard one from B&Q, nothing fancy. It's about 15-20cm away from any lemon balm shoots. I put both the JA and LB in that container as they're both supposed to take over your garden! I am aware it takes special skill to kill one, perhaps I should feel blessed.

I'm not sure about keeping it more dry - it was previously (year 1) under a wisteria where it rarely got any water and it was clearly unhappy (that is when its friend died). Though maybe I've moved it from one extreme to another.

I haven't dug it up recently to check the roots, but if it were vine weevil, I think the clematis and fuchsia nearby would be affected too?