One of the easiest and most productive plants to grow in your polytunnel, courgettes can provide a high yield over a long harvesting period. Immature fruits can be picked and used as courgettes, while leaving the fruit to mature will yield large marrows. The taste is best when the fruits are smaller, though the large green marrows can also be used in a variety of recipes – 'spiralising' these to form a vegetable alternative to spaghetti is particularly in vogue. Whatever you want to do with them once they are grown, you will find that courgettes can be a great addition to your polytunnel.
Courgettes can be sown indoors in pots from April-May or directly into the soil from June, or a little earlier if they have some protection from a cloche. Sow seeds on edge in pots to a depth of around 1cm. If you are starting your courgettes in pots, it is important not to sow seeds too early as the plants will grow quickly once germination has occurred and you will need to have time to prepare the growing area and harden off your plants properly before they go to their final growing positions. Make sure that you leave courgettes enough space to grow. Each plant will need around 1m² – but only two plants are needed to provide more than enough courgettes for the average family.
The growing area for courgettes should be prepared by creating a pocket of compost, left in the form of a mound. Plant or sow seeds directly at the top in the centre of the mound. When watering your courgettes, take care not to get water on the leaves and try to water at the roots. Your courgette plants will require pollination in order to create fruit. Each plant will have male and female flowers – if there is a shortage of pollinators, you can pollinate plants yourself using a tiny brush. This is not usually necessary however – just remember to leave the polytunnel doors open whenever possible to allow pollinators to enter and sow companion plants to encourage pollinators to enter. Nasturtiums, for example, are a great companion plant for courgettes and squash – you can eat them too.
You can begin to remove the fruits when they reach around 10cm in length. Use a sharp knife to cut fruits off at their bases. Excess courgette flowers can also be eaten – often they are stuffed and/or made into fritters. Once the courgette plants reach maturity, you can harvest up to four or five small courgettes a week from each plant! Removing fruits regularly will help the plant to keep producing more over a longer period. Of course, you can also leave some fruits to become large marrows. Courgettes can be harvested between July and can go on producing until September or even later in the year.
Sowing outdoors – May to June
Sowing indoors – April
Planting out – June
Cutting time – July to September