How to Prune penstemon 'Precious Gem'?
Deadhead after flowering to maintain vigour and prolong flowering, then cut back to 15cm in late winter or early spring

penstemon 'Precious Gem' · Penstemon 'Precious Gem'
Penstemon cultivation in fertile, well-drained soil in full sun or partial shade. In cold areas, protect plant overwinter with a dry winter mulch
Deadhead after flowering to maintain vigour and prolong flowering, then cut back to 15cm in late winter or early spring