When to prune
How and when to prune garden flowers, shrubs and trees
Nepeta. Shear off half way during November, then cut back to new shoots near the base in March.
Festuca or fescue grass. Comb through to remove dead foliage and trim off seedheads in February, earlier if self-seeding is a problem.
Eupatorium maculatum. Cut back stems to near ground level after flowering - i.e., in autumn.
Penstemon. Trim off dead foliage to within 20cm of the ground in November, protect the crown with a layer of dry leaves or chipped bark. Trim back to near ground level in March.
Echinacea purpurea. Cut back to near the ground in October.
Ligularia. Tidy plants during November. Cut back to near ground level during March.
Rodgersia. Cut back to near ground level during November.
Linaria purpurea 'Canon Went'. Cut back to 15cm in November.
Sisyrinchium. Cut back flower stems to their base during October, earlier if self-seeding is a problem.
Rudbeckia. Cut back to near ground level during November, protect the crown with a layer of dry leaves or chipped bark.