They are easy to grow and incredibly prolific, growing feakishly fast in the summer. Two or three plants will be more than enough Your only problem in fact will be working out what to do with all those courgettes. Courgette bread anyone?
Sow seeds indoors in pots at a depth of 2cm from April. They will need temperatures of 20 degrees celsius to germinate so leave the pots on a sunny windowsill. Harden off well and transplant in June. Don’t be fooled by their size when you are first planting the seedlings out. Courgettes grow to large, hungry and thirsty plants so leave 50-75cm between plants. Dig plenty of well rotted compost in to the soil before transplanting.
Never let the soil dry out – use a mulch around the plants to preserve moisture. They will need lots of water particularly when the courgettes are starting to swell. If you have added plenty of manure when planting, they shouldn’t need feeding, but if you think the growth is slow use a general purpose organic fertiliser, or make your own comfrey tea. Courgette plants have male and female flowers on the same plant and insects will generally carry pollen from one to the other at which point the female flower starts to become a fruit. If the plants are grown under cover, you may have to pollinate them by hand.
Harvest regularly when the courgettes are about pencil length. They are at their best at this stage, and quickly become watery and relatively tasteless thereafter. The more you pick the more fruit the plant will produce. Don’t leave big marrows on the plant as it will reduce the production of new fruits.
Powdery mildew is the most common problem and appears as a white powder on leaves at the end of the summer. It is not a huge issue and mainly just affects the leaves. A weekly spray of milk at a concentration of 1 part milk to 9 parts water will significantly reduce the severity of powdery mildew infection. Slugs are an issue for newly planted seedlings – protect them carefully!
Try sowing courgette seeds in biodegradable pots, they can then be sowed out (pot and all) in to the soil.
Allow at least some of your courgettes to grow in to giant marrows at the end of the season, then pick and store them. The thick skin will preserve them over the winter.