How to Grow Courgettes: Two Plants Is Plenty

Courgettes are the crop that teaches people to grow vegetables, mostly because they are almost impossible to fail with and they produce far more than anyone expects. The two things worth knowing before you start are how few plants you need and how small to pick, and both are the opposite of what instinct suggests.

The short answer

Plant two, not five. Give each one at least a square metre in the ground or 30 to 40 litres in a pot. Water at the base, never over the leaves. Pick at 10 to 15 cm and pick every couple of days, because a fruit left to swell slows the whole plant down. If the first small fruits rot at the tip, that is incomplete pollination, so hand pollinate for a fortnight and it stops.

Two plants, and why#

A single healthy courgette plant produces roughly twenty to thirty fruits across a season if you keep picking. Two plants feeds a household through summer with some to give away.

The reason people plant five is that the seedlings are cheap and small and it seems mean not to. Then July arrives and there are courgettes in every meal and neighbours crossing the road to avoid you.

Space matters as much as number. Each plant wants about a square metre, because those leaves get big, and crowded plants get mildew earlier through poor air movement.

Sowing and planting out#

Courgettes are frost tender and grow fast, so timing beats getting ahead.

Sow indoors two to four weeks before your last frost date, one seed per pot, on their side about 2 cm deep. They germinate in under a week in warmth.

Plant out only after the last frost, and harden them off for a week first. Sown too early they sit indoors getting leggy and check badly when planted out. Sown directly outdoors after the frost date they catch up with indoor-sown plants surprisingly quickly.

Plant into ground with plenty of compost worked in. They are hungry and thirsty and it shows.

Bush varieties

Compact, upright, suited to containers and small beds. The default choice for most gardens.

Trailing varieties

Send out long stems and cover ground. More fruit per plant, and they need the space or a frame.

Yellow varieties

Same plant, easier to spot among the leaves, which genuinely helps you pick before they turn into marrows.

Round varieties

Good for stuffing, and they hide even more effectively than the long ones.

The rotting baby fruit problem#

This is the most common courgette question and the answer is reassuring: it is usually not a disease.

Courgettes carry separate male and female flowers. The female has a tiny fruit behind it before it even opens. If that flower is not pollinated, the fruit it is attached to gets a short way and then shrivels and rots from the flower end.

It happens most in early season, when plants often produce a run of male flowers first and there are fewer insects about in cool weather.

The fix takes ten seconds. Pick a male flower, which sits on a plain thin stem with nothing behind it. Peel the petals back to expose the pollen. Dab it into the centre of a female flower. Do it in the morning while both are open.

Two weeks of that and the plant will usually be setting on its own.

Watering, and the one rule#

Water at the base, not over the leaves.

Courgette leaves are enormous and they are the entry point for powdery mildew, which is the disease that eventually finishes every courgette plant. Wet foliage in the evening is exactly what it wants.

Water deeply and consistently rather than a little often. Drought stress makes mildew worse and it also causes fruit to abort.

Midday wilting in hot weather is normal and not a sign of underwatering: the leaf surface area is simply too large to keep up. Judge by the morning, not the afternoon.

Picking small, and picking often#

This is the part that decides how much you get.

Pick at 10 to 15 cm. The texture and flavour are much better small, and more importantly, every fruit you leave to swell signals to the plant that it has reproduced successfully and it slows down setting new ones. One marrow left on the plant can cost you a fortnight of production.

They swell fast in high summer. Check every two days, and look underneath the leaves, where the ones you miss are hiding.

Cut with a knife rather than twisting, because a torn stem is an infection route.

The flowers are also worth eating. Male flowers can be picked freely once the plant is setting well, since you only need a few for pollination.

Powdery mildew, realistically#

By late summer courgette leaves go grey and dusty. That is powdery mildew and it is close to inevitable.

What you can do is delay it: space the plants, water at the base, water consistently, and remove the worst leaves as they go rather than letting them sit.

What I would not do is spray. By the time mildew is established the plant has usually produced most of what it is going to, and the season is ending anyway. Milk sprays and bicarbonate mixtures circulate widely; the evidence for them is thin and I would not present them as reliable.

A courgette plant that mildews in September has done its job.

Growing in containers#

Perfectly workable with the right volume.

Thirty to forty litres minimum for one plant. Below that it stalls, the fruit stays small, and people blame the variety. Bush varieties suit pots better than trailing ones.

Expect to water daily in summer and to feed weekly with a high potash feed once fruiting starts, because a container runs out of nutrients in about six weeks.

What it costs#

A packet of seed

$3 to $6, and it contains far more seed than you need. It will do two or three seasons.

Two plants from a nursery

$8 to $18, and worth it if you missed the sowing window.

Compost for the planting hole

$10 to $20, or free if you make your own. They repay generosity here.

One 40 litre container

$25 to $70 if you are growing in pots. Do not economise on volume.

High potash liquid feed

$10 to $18, and only needed for container plants or poor soil.

Where this needs adjusting#

In a short or cool season, start indoors and choose a bush variety, and expect a later, shorter run of fruit. Fleece over the young plants for the first fortnight helps.

In a hot dry climate, they will need afternoon shade and much more water, and mildew arrives earlier. Mulch becomes essential rather than optional.

And if you are in a very small space, one plant in a large container is a genuinely worthwhile crop, whereas five plants anywhere is a mistake regardless of the space available.

Where the guidance here comes from#

The hand pollination method and the pick-small rule are conventional, and both are things I only started doing properly after two seasons of losing early fruit and letting marrows form. For sowing dates, spacing and mildew management the RHS advice on growing your own is the reference, and Garden Organic covers non-chemical disease management honestly, including being clear about what is not well supported.

The short version#

Two plants, a square metre each, plenty of compost. Sow two to four weeks before your last frost and plant out after it. Water at the base, consistently, and mulch. Hand pollinate for the first fortnight if the small fruits rot. Then pick at 10 to 15 cm every couple of days and keep looking under the leaves.

Related reading#

• How to start a vegetable garden: where courgettes fit in a first year plan.
• Container gardening: the pot volume this crop needs, and why.
• Garden planner: sowing dates and why two plants is a decision worth writing down.
• Food garden ideas: growing this in a border rather than a vegetable bed.