Hyssop

Hyssop is a hardy subshrub and gets through the winter in the lowlands of Germany, Austria and Switzerland outdoors without protection. Cut it back lightly in autumn after flowering so that it stays compact; do the hard cut into old wood only in spring after the frost. Wrap container hyssop in horticultural fleece or hessian and place it against a sheltered house wall, as roots in pots freeze through more than garden soil.

Hyssop propagates well in three ways. Sowing: Hyssop needs light to germinate: don't cover the seeds with soil, only press them in lightly and keep them moist. Start indoors from mid-March at around 18 to 20 °C; germination needs patience and usually takes 2 to 3 weeks (about 14 to 20 days). Plant outdoors from mid-May when no more frosts threaten, because young plants are frost-tender. Sow directly outdoors from May at the earliest. Cuttings: In early summer (May to June), cut shoot tips that are not yet woody, about 8 to 10 cm long, before the plant sets flower buds. Remove the lower leaves, insert in moist seed substrate and cover with a transparent lid to keep the humidity high. At about 20 °C, first roots form after 2 to 4 weeks, visible in new growth. Division: In spring or autumn, dig up older, well-established plants and divide them with a sharp spade into several pieces. Each piece should get enough roots. Replant straight away and water in well. Division rejuvenates the mother plant at the same time and counteracts woodiness; it is especially sensible for plants 3 to 4 years old. Note: since hyssop is a subshrub with a woody base, it is best to divide younger, still herbaceous clumps; heavily woody old plants are harder to divide. In that case, layering a flexible shoot works as an alternative.