Should you deadhead monkshood?

Once monkshood has become established, avoid transplanting or dividing the clump. Their thick, fleshy roots dislike being disturbed. Deadheading will encourage a second round of flowers. Since these make nice cut flowers, bring some indoors and you'll be rewarded with additional blooms outdoors.

When should I cut down monkshood?

The same basic concept works for these late summer and fall bloomers: Monkshood (Aconitum), Michaelmas Daisies (Aster), Joe-pye Weed (Eupatorium), Helen's Flower (Helenium), Beebalm (Monarda), Summer Phlox (Phlox paniculata), Autumn Stonecrop (Sedum) and many, many others. June is the ideal time for cutting these back.