Zinnia

The zinnia is annual and dies at the first frost. You cannot overwinter it; put it on the compost in autumn. To keep the variety, collect ripe seed from single flowers in late summer, dry it further and store it cool and dry; next spring after the Ice Saints (from mid-May) sow directly in the bed, or sow indoors from April.

Sowing (main method): Zinnia elegans is an annual plant that you propagate most easily from seed. For raising indoors, sow from February/mid-March to the end of April in seed compost on a warm windowsill or in a greenhouse. The germination temperature should be 18 to 22 °C. The seeds germinate after about 8 to 15 days. For earlier flowering, sow indoors 4 to 6 weeks before the last frost. Alternatively, sow directly in the bed as soon as there is no more risk of night frosts and the soil has warmed to at least 15 °C, so after the Ice Saints in mid-May. Sow about 0.5 to 1 cm deep. Spacing 20 to 30 cm depending on the variety. You collect your own seed in autumn by letting the flower heads ripen fully, drying them and storing the seed cool and dry. Note, however: offspring of F1 hybrids and seed after open pollination often do not match the parent variety (new colour/shape variants), and double flowers produce hardly any viable seed.

Cuttings (supplementary method): Cuttings are possible and worthwhile if you want to propagate a particularly attractive plant or extend the season. In early summer, cut a shoot 10 to 15 cm long, preferably without flowers, in the morning just below a node, remove the lower leaves and put the cutting in water or insert it in moist seed substrate. In a warm, bright position, roots form within about 3 to 4 weeks, after which you can pot up the rooted cutting. Since zinnias are frost-tender, this method mainly makes sense in summer.