Growing Courgettes in a Greenhouse

Growing Courgettes in a Greenhouse

Courgettes also go by the name of zucchini. These incredibly tasty and versatile vegetables can be grown in greenhouses with ease. Read on to find out more about what you need to do to grow courgettes in a greenhouse.

What are the benefits of growing courgettes?

There are many kinds of courgette plants available. These include yellow courgettes, green courgettes and even some that can climb upwards instead of growing outwards. If you are interested in growing different vegetables, starting with courgettes could be the ideal place to begin. It can be enjoyable to sow different kinds of courgette seeds.

One of the benefits of experimenting with growing courgette seeds is that it can help you find out more about how different plants will grow inside your greenhouse. Some plants may not work as well in your weather conditions. Sowing different courgette seeds will also allow you to taste different courgettes so you know which ones you enjoy the most and can choose your favourites in future.

Need a new greenhouse? Shop the range of deals at South West Greenhouses

chopped courgettes on a chopping board

When to sow courgette seeds

It’s best to sow courgette seeds between March and May. Courgette seeds should be sown around 1cm deep in well-fertilised soil. Place a single seed in a pot that’s around 7.5cm in size. The plants mustn’t be squashed together. If you have purchased a packet of seeds, it’s best to sew them all instead of saving some of them for next year. As some of the seeds might not be successful, it can be helpful to have various plants available. The seeds don’t always keep well into the next year.

Make sure you label all of your pots. This ensures you don’t forget which one is which. The pots should be watered well. If you can, cover your pots with a propagator lid and leave them in a warm area for a week so they can propagate.

You’ll need to check on the seeds regularly. When you first start to see growth, take the propagation lid off. The first signs can include evidence of small stems and tiny leaves. Place the pots in a sunny part of your greenhouse to make sure they have as much light as possible. This should ensure you quickly see a pleasing amount of growth.

Key Steps in Growing Courgettes

Choose the right variety

When you’re looking for a courgette variety to grow inside your greenhouse, it’s best to opt for a compact, bushy type that grows well in containers.

Prepare your soil

Before you start planting, prepare your soil in the greenhouse. Courgettes need soil which is rich in nutrients. Add manure, compost or other kinds of organic matter to your soil to make it more fertile. The soil also needs to be well-draining.

Planting and spacing 

Your courgette seeds need to be planted in late spring, once there is no more risk of frost. Seeds can be started indoors and then transplanted into containers or straight into the ground inside your greenhouse. Make sure you’re planting the seeds 2 to 3 feet apart and ensure they are being planted at a depth of 1 inch.

Temperature and humidity

If your courgettes are to grow well, they will need warm temperatures and lots of humidity. It can be beneficial to install a thermometer and a hygrometer inside the greenhouse so you can ensure you have the right conditions. Aim for a temperature between 18 and 24°C when growing your courgettes. A good way to boost the humidity inside the warehouse is to mist the leaves of your courgette plants with water.

basket of sprouting courgettes

Watering and fertilising

If your courgettes are to prosper, they will need to be watered and fertilised regularly. Drip irrigation systems can be used to water plants. A balanced fertilizer will enable you to provide the nutrients that are required. Your plants need to be watered deeply and regularly. This is because courgettes have shallow roots. They may become stressed swiftly if you don’t water them sufficiently.

Pest and disease control

Unfortunately, courgettes can be vulnerable to multiple pests and diseases. These can include aphids, whiteflies, powdery mildew, and blossom end rot. Try to overcome these challenges by making use of insecticidal soap or neem oil. Good air circulation will also help. You can also stay one step ahead of diseases by practising crop rotation and keeping your greenhouse in a clean condition.

Training and pruning

It’s not uncommon for courgette plants to become very large and start to sprawl. This is why you need to train and prune them. Stakes and trellises are often used to support these plants, and you can also use them to remove side shoots and dead leaves. The main stem needs to be left intact due to the fact as most of the fruit will be produced here.

Related greenhouse growing guides:

Transporting your young plants to larger pots

You must take good care of your courgette plants as they are growing inside your greenhouse. Healthy courgette plants normally shoot up quickly. This is why you will need to consider taking them to a bigger pot at some point so they have enough space to flourish. Feeding the plants with a liquid fertiliser will enhance their strength and vitality.

You can also stake your plants up to prevent them from drooping awkwardly. Although young courgettes do need to be watered, try not to over-water them.

Planting out your courgettes

Maybe you have a larger greenhouse? If so, you can keep your courgettes growing under glass. They will most likely prosper. Alternatively, you can move the courgettes into larger pots and keep the pots inside your greenhouse. Once the risk of cold frosts has subsided, you can move the courgettes outside for planting. It’s wise to acclimatise your plants to their new condition slowly. You can do this by pacing them outside in their pots for a few hours before you actually plant them in your garden.

Try to find a sunny, sheltered position then plant your courgettes inside deep holes as this will enable their roots to spread. Perhaps you are planting out several courgettes? If so, these should be positioned around two feet apart. This will be beneficial as the plants will require a lot of room to spread out. From this point, make sure the plants are watered well and be vigilant for any slugs.

Related guides:


Once your courgettes reach a length of approximately 15cm, they are ready for harvesting. They need to be picked regularly to encourage more fruit to grow. This will also stop them from overripening and becoming too tough. You can cut fruit from the plant with scissors or a sharp knife. Don’t pull or twist as this can cause damage to the stem.

Growing courgettes in a greenhouse can be incredibly rewarding and enjoyable. Follow the steps above to build a delightful harvest of taste-packed home-grown courgettes.


We hope you enjoyed our post on growing courgettes in a greenhouse.

If you have any questions, leave them in the comments, or contact us at

matt garner Author: Matt Garner
I'm an amateur gardener based in Birmingham in England, utilising my 30 years experience to help others learn all about gardening for South West Greenhouses. My specialist expertise are with assembling and dismantling greenhouses of all shapes and sizes. I've spent countless years growing fruit and vegetables at Walsall Road Allotments, and I was also a proud member of the Balsall & District Horticultural Society for many years. Linkedin | Twitter