Killer plants should only ever be in comedy musicals. This was never going to work.
Any adaptation of John Wyndhams story about giant shuffling plants comes up against a very large obstacle: killer shrubs are inherently not scary (ask M. Night Shyamalan). This modernised BBC version tries to tackle the problem by refusing to submit to campness and making everything very serious and loud. Aside from a fun turn from Eddie Izzard as the baddie, arch in manner and brow, its piffle. And the dull hero (Dougray Scott) deserves mulching.