Watermelon

Watermelon is an annual and dies with the first frost. It cannot be overwintered, only the seed can. For that, take seeds from fully ripe fruits, dry them well and store them dry and cool; start them on the windowsill from March/April and plant them out only after the Ice Saints.

In the home garden you propagate watermelons exclusively by sowing. Cuttings are theoretically conceivable, but so unreliable that they are not worth it. Start the seeds indoors from mid to late April: put one seed about 1 to 2 cm deep in each of several individual pots with nutrient-rich substrate. For quick germination (around 5 to 10 days) you need warmth, at least 22 to 24 °C at the roots. A bright windowsill above a radiator or a mini greenhouse with a heat mat helps with that. As soon as the first true leaves appear, carefully pot on into larger containers; the roots react sensitively to disturbance, so keep the root ball together as far as possible. The young plants go into the open ground or greenhouse only after the Ice Saints (mid-May), when no more frosts threaten and the soil is at least 18 °C; before that, slowly get them used to sun and outdoor air over a few days. For the Central European climate with short summers, it is best to choose early-ripening, small-fruited varieties such as ‘Sugar Baby’, which still ripen in cool years. You can collect your own seed in autumn from fully ripe fruits, but only from open-pollinated varieties, because the next generation of F1 hybrids turns out uneven. Rinse the seeds clean, dry them well and store them cool and dry; viability drops noticeably after a few years, and fresh seed germinates most reliably.