Growing courgettes is a super easy activity for gardeners, and these spreading plants thrive in polytunnels and greenhouses. Plus, with a harvest that can last through summer until the end of autumn, courgettes are a long-term investment in your garden that bring you plenty of health benefits. Read on to find out how to grow courgettes in your polytunnel.
One of the easiest and most productive plants to grow in the UK, courgettes can provide a high yield over a long harvesting period. Courgettes are native to northern Italy, meaning that their natural growing conditions are easy to recreate right here in the UK. However, although you may be able to grow courgettes in a warm spot of your garden, the most successful way of nurturing strong courgettes is in a polytunnel. If you use a polytunnel for growing courgettes, you can recreate their natural Mediterranean climate throughout the colder months to guarantee thriving courgettes.
You can pick and use immature fruits as courgettes, but leaving the fruit to mature will yield large marrows. The taste of courgettes 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.
You can sow courgettes indoors in pots from April to May, or directly into the soil from June. However, you can also sow them into soil 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.
You should prepare the growing area for courgettes by creating a pocket of compost, left in the form of a mound. Then, plant or sow your 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.
Usually, you can begin to harvest courgettes as early as June. Then, the plants will continue to produce new fruits all through summer, only going into dormancy once the first autumn frost sets in. However, in a polytunnel, you will be able to expand this growth time!
You should be able to start picking courgettes when they reach around 10 – 12.5 cm in length. 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.
To harvest courgettes, you can simply use a sharp knife to cut the fruits off at their bases. Also, you may eat excess courgette flowers – 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!
Sowing outdoors – May to June
Sowing indoors – April
Planting out – June
Cutting time – July to September
With its low maintenance growth and long harvesting period, growing courgettes is one of the most beneficial things you can do in your polytunnel. Follow our guide on ‘how to grow courgettes’ for thriving fruits all summer long!