Courgette

The courgette is annual and dies at the first light frost. It cannot be overwintered, not even in a greenhouse. Harvest all the fruit before the frost, clear away the plant remains and raise new plants indoors from mid/late April, to plant out after the Ice Saints (mid-May · week 20).

You propagate courgettes exclusively from seed. It is an annual plant with no sensible vegetative propagation option (no runners, no divisible rootstocks, no cuttings). You have two ways: raise indoors from mid-April (one seed per pot 8 to 10 cm across, 2 to 3 cm deep, warm at around 20 °C, bright; it germinates after 7 to 10 days) and plant out after the Ice Saints from mid-May outdoors. Or you sow directly in place from mid/late May, as soon as there is no more risk of late frosts; then you take the first harvest about 8 weeks later. You can collect your own seed only from open-pollinated (not F1 hybrid) varieties: let one courgette ripen fully (it becomes large and hard), take out the seeds, wash them and dry them for several weeks in an airy place. Note that courgettes are cross-pollinators, pollinated by insects. For propagation true to variety you need several plants of the same variety flowering at the same time, a large distance (300 to 500 m in the literature) from other cucurbits, and ideally hand pollination of the flowers that are open for only one day. Important for safety: if your courgette crosses with ornamental gourds, the plants grown from them can bear bitter fruit with a high content of bitter compounds the following year, which causes stomach ache and nausea. So always taste home-grown fruit raw first. If it tastes bitter, spit it out and throw it away. When in doubt, bought seed is the safer choice for the home garden.