Courgettes are one of the most rewarding vegetables to grow in the UK. They are prolific, versatile in the kitchen and surprisingly easy to cultivate once you understand their needs. From a single plant you can expect a steady stream of glossy green fruits all summer long, with many gardeners finding that even two or three plants are more than enough for a family. Despite their relative ease, timing is everything when it comes to courgettes. Knowing when to plant them ensures strong growth, abundant harvests and fewer problems with pests and diseases.
The life cycle of courgettes
Courgettes are part of the cucurbit family, which also includes pumpkins, marrows and cucumbers. They are tender annuals, meaning they complete their life cycle within one season and cannot tolerate frost. Their growing cycle begins with seed germination, followed by rapid leaf and stem growth, flowering and then fruit production. To enjoy a long harvest, the plants must be sown and planted at the right time so that they benefit from warm conditions and have plenty of opportunity to fruit before autumn frosts return.
The best time to sow courgette seeds
In the UK, courgettes are usually started indoors from late March through to May. Seeds need warmth to germinate, ideally around 18 to 21 degrees Celsius, which is why windowsills, heated propagators or greenhouses are commonly used. Sowing too early in unheated conditions often results in slow or failed germination. By starting seeds indoors in spring, gardeners give plants a head start before moving them outside when the weather is reliably warm.
When to plant courgettes outdoors
Courgettes are not planted directly outdoors until late May or early June, once all risk of frost has passed. Even a light frost can kill young courgette plants, so patience is essential. In southern parts of the UK, planting out may be possible slightly earlier, while in northern regions it is often safer to wait until early June. Courgettes thrive in warm soil, so delaying planting until conditions are suitable ensures stronger, healthier plants that will produce fruit quickly.
Why timing matters for courgettes
Planting courgettes too early can be a disaster. Frost or cold nights stunt growth or kill young plants outright. Even if they survive, stressed plants often produce fewer fruits and are more vulnerable to disease. On the other hand, planting too late shortens the growing season, reducing yields. The aim is to strike a balance by giving the plants as long a growing season as possible while avoiding the dangers of cold weather. This is why indoor sowing in spring followed by outdoor planting after frost is the tried and tested method.
Successional sowing for longer harvests
Courgettes grow quickly, and one planting is often enough for a summer of harvests. However, some gardeners like to stagger sowings by starting a second batch of seeds in May. This ensures fresh young plants continue producing later into the season, replacing older plants that may tire. Successional sowing also spreads out the harvest, avoiding an overwhelming glut of courgettes all at once. Timing these sowings correctly means you can enjoy a steady supply from early summer until autumn.
Growing courgettes directly outdoors
While most gardeners start seeds indoors, it is also possible to sow courgettes directly into the soil outside. This is best done in late May or early June when the soil has warmed. The risk with direct sowing is that germination can be patchy, and young seedlings may be more vulnerable to slugs and pests. However, it remains a useful option for those without indoor space or equipment. Success depends on waiting until conditions are reliably warm and the soil is fertile and free draining.
Soil preparation before planting
Courgettes are hungry plants, and soil preparation is just as important as timing. Beds should be prepared in spring by digging in plenty of organic matter such as compost or well rotted manure. This enriches the soil and improves its ability to retain moisture, which is vital for courgettes that dislike drying out. By the time plants are ready to go outside in late May or early June, the soil should be nutrient rich and warm, providing the perfect foundation for vigorous growth.
Regional differences in planting time
In southern regions of the UK with milder climates, courgettes can often be planted outdoors in mid to late May. In northern areas where frost lingers longer, it is safer to wait until June. Gardeners at higher altitudes may need to delay planting even further or provide cloches and fleece for protection. Local conditions always take precedence over general guidelines, and checking the forecast before planting is a sensible precaution.
The importance of aftercare once planted
Timing does not end with planting. Courgettes must be cared for correctly to make the most of the growing season. Regular watering is essential, especially during dry spells, as inconsistent moisture can lead to misshapen fruits. Feeding with a high potassium fertiliser once the plants begin flowering encourages more fruits to set. By planting at the right time and maintaining consistent care, gardeners maximise the return from each plant.
Extending the season
For those who want to push the season, protective measures can make earlier planting possible. Cloches, cold frames or polytunnels help shield plants from late frosts and provide warmth in early spring. These structures allow gardeners to plant courgettes outdoors a little earlier than usual, extending the season. However, even with protection, extreme cold can still damage plants, so careful monitoring is required. Similarly, plants can be protected in autumn to squeeze out a final few harvests before frosts arrive.
Conclusion
So, when should you plant courgettes? The answer is clear. Sow seeds indoors from late March to May, then move plants outdoors in late May or early June once the risk of frost has passed. This timing ensures strong germination, healthy growth and maximum yields before autumn arrives. Successional sowing in May can extend the harvest, while regional climates influence exact planting dates. By respecting the tender nature of courgettes and waiting for the right conditions, you will be rewarded with abundant crops of this versatile and delicious vegetable.
