By Geoff_val
United Kingdom 
This has appeared in our garden and is growing fast.....! Is it a Triffid? Help!
5 Oct, 2015
Answers
It may flower another year then?
5 Oct, 2015
Beanstalk. Your name really is 'Geoff' and not 'Jack' I hope!
5 Oct, 2015
I agree tree mallow - one appeared in my veg patch this year. (And like a soft hearted idiot I let it stay until it had finished flowering...)
5 Oct, 2015
I think it's a tree mallow, Malva arborea, especially if you are near the coast.
5 Oct, 2015