Shiso

Shiso is annual and dies with the first frost. Genuinely overwintering the plant does not work. Let a few plants go to seed in autumn, or collect ripe seeds and sow anew from March/April on the windowsill.

The easiest way to propagate shiso is by sowing, which is the most common and most reliable method. A short cold spell improves germination markedly: before sowing, put the seeds in the fridge at 0 to 5 °C for about one to two weeks (preferably in slightly damp sand). Then sow from March/April on a bright windowsill, or directly outdoors from mid-May, once the last frost is over. Important: shiso needs light to germinate. Press the seeds only onto moist seed compost and do NOT cover them (at most with a very thin layer), because they germinate poorly under a layer of soil. At 18 to 22 °C germination takes around 10 to 21 days; keep the compost evenly moist during that time. In a good spot shiso readily self-sows: if you let a few plants go to seed in autumn, you will find new young plants the following year without any effort. If you want to avoid that, cut off the flower heads before the seed ripens.

Cuttings work well if you want to propagate a particularly aromatic plant true to type. In late spring or early summer, cut shoot tips 8 to 12 cm long just below a leaf node and remove the lower leaves. The cuttings root easily in a glass of water in a bright place (alternatively in moist compost under a cover). After about two to four weeks you have a solid root system and can pot them on or plant them out.