Very tall garden plants (Leasgill LA7)

Have been thinning out some of my large perennial garden plants. Both are up to 2.5 metres high and vigorous growers. Google the names for pictures and further details.
1. Eupatorium maculatum 'Riesenschirm' (Joe-Pye Weed)
'Riesenschirm' is a tall cultivar, to 2.5m in height, with large heads of wine red flowers in late summer and autumn, dark stems and deep green foliage. A very impressive plant which is extremely attractive to bees and butterflies.
2. Cephalaria gigantea (giant yellow scabious)
A perennial forming a clump of pinnately lobed basal leaves, with tall, branched stems carrying light yellow flower-heads to 6cm across in summer