How to prune penstemon 'sour grapes'

Mid to late spring, after the worst frosts have passed and new growth is visible. Cut stems back to the lowest pair of healthy new shoots in spring; do not cut into bare, leafless old wood. Deadhead spent spikes during summer back to a side-shoot to promote repeat flowering through to autumn.

Annually (spring cut-back) plus deadheading through summer. Penstemon 'Sour Grapes' is a semi-evergreen subshrub that flowers best with a spring prune and regular summer deadheading. Do not cut back hard in autumn — old stems give frost protection. In spring, once winter damage is clear, cut to the lowest strong new shoots and remove any dead wood.

Cut stems back to the lowest pair of healthy new shoots in spring; do not cut into bare, leafless old wood. Deadhead spent spikes during summer back to a side-shoot to promote repeat flowering through to autumn.