Mameha, you might find this RHS advice helpful.
It could be an Eryngium (Sea Holly). They self seed in my garden
It could be 'Pale Persicaria' which is a weed but I believe that there are also cultivated forms of persicaria
Dove - They'd been out for several weeks and I had planned to start leaving them out. Just a case of bad luck I think.
I'm based in the south and last week lost two broad bean plants to frost because I forgot to put the back in the greenhouse until 22.00. I'd say it would be very risky for you given the current forecast.
Matty2, surely a visit to the GC is medicinal . You could try that approach.
I have cut down my Miscanthus. I have found that if I leave it any later it becomes harder to do without cutting the new shoots. It would be wise to check to see if the new growth has started to appear.
WUM - wind up merchant?
Scale insects will probably be the cause of the leaf drop. You need to check the back of each leaf paying attention the the central vein area. I lost a 6 foot lemon tree to a scale insect infestation.
Rose. Cerinthe, Primroses, Kerria Japonica and Hellebores in my garden. Would have had a dandelion but I dug it up yesterday.