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The best time to sow courgettes is in late spring, once the last frost has passed and the soil has warmed up nicely.
If you’ve been wondering when to sow courgettes, the short answer is simple: timing matters more than almost anything else with these hungry, fast-growing plants.
Get it right and you’ll be harvesting tender fruits within weeks, but get it wrong and you’ll be nursing sad, cold-shocked seedlings that never quite recover.
In this post, we’ll look at when to sow courgettes indoors and outdoors, how your climate shifts the timing, and the little tricks that help you hit that sweet spot.
Let’s dig in.
When to Sow Courgettes: The Sweet Spot
Courgettes are warm-season crops, so the golden rule is to sow them when the soil and air are reliably warm.
If you’re sowing courgettes indoors, you can start them about three to four weeks before your last expected frost date.
For most temperate gardeners, that means sowing courgettes indoors in mid to late April, then planting them out in late May or early June.
1. Wait for the Last Frost
The single biggest factor in when to sow courgettes is your last frost date.
Courgettes hate the cold, and a single frosty night can wipe out young seedlings overnight.
So check your local last frost date and count back three to four weeks if you’re starting seeds indoors.
If you’re sowing courgettes directly outside, wait until at least two weeks after that last frost date.
2. Watch the Soil Temperature
Courgette seeds germinate best when the soil sits at around 15–20°C (60–68°F).
If the soil is colder than that, seeds may rot instead of sprouting, which is a common reason people ask when to sow courgettes after a failed early attempt.
A cheap soil thermometer takes the guesswork out of when to sow courgettes, and it’s worth every penny.
3. Think About Your Climate
Your climate changes when to sow courgettes more than any guidebook can.
In mild, warm regions, you can often sow courgettes outdoors from mid-spring onwards.
In cooler areas, starting them indoors or under cover is the safer bet, giving you a jump on the season.
If you garden in a short-season climate, sow courgettes indoors and treat them like the heat-loving divas they are.
How to Sow Courgettes Indoors and Out
Once you know when to sow courgettes, the how becomes a lot easier.
Courgettes are big, fast growers, so you don’t need to baby them for long.
1. Start Indoors in Pots
Sow courgette seeds on their edge, about 2cm deep, in individual pots.
They dislike root disturbance, so planting them in biodegradable pots saves you a job later.
Keep them somewhere warm and bright, and you’ll see seedlings in a week or so.
2. Sow Directly Once It’s Warm
If you’re sowing courgettes straight into the ground, make a small mound of rich soil and pop two or three seeds in.
Thin them to the strongest seedling once they’re up.
This method works brilliantly when the weather has settled and you’re past any risk of frost.
3. Harden Them Off Gently
Before planting out, harden off your indoor seedlings over a week or so.
This step matters whether you’re sowing courgettes indoors or buying plugs, as sudden cold can set them back badly.
Common Timing Mistakes to Avoid
Getting the timing of when to sow courgettes wrong is the number one reason for disappointing crops.
1. Sowing Too Early
Sowing courgettes too early leads to leggy, weak plants that sulk in cold soil.
Patience here really does pay off.
2. Sowing Too Late
Leave it too long and you’ll still get a crop, but you’ll lose weeks of harvest.
Aim for that window rather than drifting past it.
3. Ignoring Your Local Weather
Local conditions always beat generic advice on when to sow courgettes.
A warm microclimate can let you sow earlier, while a windy, exposed plot calls for caution.
So, When to Sow Courgettes?
The best time to sow courgettes is in late spring, once the last frost has passed and the soil has warmed up nicely.
If you’ve been wondering when to sow courgettes, the short answer is simple: timing matters more than almost anything else with these hungry, fast-growing plants.
Get it right and you’ll be harvesting tender fruits within weeks, but get it wrong and you’ll be nursing sad, cold-shocked seedlings that never quite recover.
Hope this post has helped you work out exactly when to sow courgettes in your own garden.