How to prune greenstem forsythia

Immediately after flowering (early to mid-spring). Remove up to one-third of the oldest stems at ground level. Trim remaining flowered shoots back to a healthy sideshoot. Do not prune in autumn or winter, as this removes formed flower buds.

Annually after flowering. Greenstem Forsythia follows the same rule as other forsythias: prune straight after flowering, before the plant sets the buds that will carry next year's blooms. It tends to be slightly more compact than Border Forsythia but still benefits from annual removal of the oldest stems at ground level to maintain vigor.

Remove up to one-third of the oldest stems at ground level. Trim remaining flowered shoots back to a healthy sideshoot. Do not prune in autumn or winter, as this removes formed flower buds.