Courgette seeds are best started indoors in pots April to June for transplanting out into their growing position once the weather has warmed up.
Fill a 7.5cm (3in) pot with compost and firm gently. Sow a seed on its side (reduces the risk of damping off disease) 2.5cm (1in) deep and cover.
Label, water and put in a propagator or on a windowsill. When roots begin to show through the bottom of the pot, put into a 12.5cm (5in) container.
Hardened off before planting them outside, once all danger of frost has passed. Plant into growing bags, soil or a large pot If seedlings are planted out too early, and exposed to a period of cold weather, it can set back their development for the whole growing season.
Choose a sunny, sheltered spot and improve the soil by digging in some well-rotted manure or compost. The simplest way to prepare the ground is to dig a hole 30cm (12in) deep and 45cm (18in) across and fill it with well rotted compost or manure. Cover with a 15 to 20cm (6 to 8in) layer of soil to make a raised mound that will provide drainage along with a rich source of nutrients.
Each courgette plant will need 1m square (3ft sq) in order to spread and avoid competing with nearby plants. (Alternatively you can grow them in large containers). To get the best results ensure you have good, nutritious growing compost and that you feed them through the season.
Plenty of water is essential, especially when the plants are in flower and then when the fruits have started to swell. Mulch to lock in moisture. If you dig in plenty of manure before planting, additional feeding is unnecessary on heavy, fertile soil. On sandy or light soil, regular drenches with a liquid feed will help boost production.
Plants under glass should be hand pollinated. The female flowers are distinguished by the swelling below the bloom. Male flowers have a prominent central core, bearing yellow pollen. The male flower is first to appear and the female flowers will follow. To hand pollinate, remove the petals from a male flower; push the core into the centre of the female flower. For a high success rate, use a different male for each female flower.
To keep courgette plants productive you need to harvest the fruits regularly during the growing season. They are best picked young when they are about 12cm long. They will keep for a few days in the fridge once picked.