Courgettes: companion plants, spacing and planting

Other names

Zucchini, marrow

Botanical name

Cucurbita pepo subsp. pepo convar. giromontiina

Family / Genus

Cucurbitaceae / Cucurbita

Plant category

Fruit vegetables

Peter Turner Photography/Shutterstock.com

Courgettes, the 'little squash', can be harvested just 5 weeks after planting, since you basically pick the fruits continuously while they're still unripe. You can often keep this up right until the first frosts, as the plants are quite robust.

The main difference between a courgette and a squash is that courgettes don't form runners and are always harvested unripe. Though the lines are blurry. There are climbing courgette varieties and squashes without runners. The pattypan squash is also sometimes listed as either squash or courgette.

Facts and figures

Light requirements

Sun / partial shade

Nutrient requirements

Heavy feeder

Difficulty level

Easy

Culture (according to Gertrud Franck)

A - tall or wide crops, almost year-round

Culture (according to Sister C. Weinrich)

Main crop

Growing period

60 days

Row spacing

100 cm

Plant spacing

100 cm

Sowing depth

3 cm

Germination temperature (minimum)

13 °C

Germination temperature (optimal)

18 - 24 °C

Germination type

Dark

Pre-growing period

30 days

Planting & harvest times of Courgette

Direct sowing

Pre-grow

Transplant

Harvest

Direct sowing from Mid May to Mid June. Transplant to bed from Mid May to Mid June. Pre-grow about 30 days before transplanting, approximately between Mid April and Mid May. After a growing period of 60 days, harvest can begin around Mid June and continues until Late October.

Sow and plant Courgette

The plants often grow very large. If you don't have much space, make sure to look for compact varieties or grow your courgettes in a large pot (at least 30 litres).

You should have at least 2 plants, otherwise yields can be very low if there's no pollinator plant nearby.

Courgette plants, like squash or cucumber plants, don't like having their roots disturbed. So don't prick them out — sow the seeds directly into larger pots (8 cm or more).

Good and bad companions of Courgette

Courgettes need plenty of room, around one square metre per plant, and full sun. Carrots, parsnips and onions have proved their worth in the rows alongside, as have beans, beetroot, dill and fennel. Basil, chamomile and marjoram are happy in among the courgettes. Sow radishes around the young plants in spring, and you will have harvested them before the big leaves need the space.

Put winter radish somewhere else, and cabbage is considered a poor neighbour for courgettes. Keep your distance from cucumbers, squash and melons, as they share mildew and viruses that aphids carry from plant to plant. For the same reason, do not put young courgettes right next to older ones.

Good neighbours

Bad neighbours

Predecessors and successors of Courgette

As a preceding crop you can sow a green manure or plant broad beans, which are already harvested by the time the courgettes go in and leave behind a well-fed soil. Lettuce and radishes work as an earlier crop too, so the space doesn't sit empty for long. In that case, though, only feed the soil shortly before the courgettes go in.

Courgettes return to the same bed after four years at the earliest, and the same goes for pumpkins, cucumbers and melons. They share diseases that survive on plant debris in the soil. Peas, beans or an early sowing of field beans make good predecessors, because courgettes are hungry feeders and need plenty of nitrogen. If sunflowers grew in the bed, wait three years, as both pick up white mould. After courgettes the soil is in good shape. The following year onions, garlic, leeks and shallots do well there, and so do carrots and parsnips if you kept the courgettes properly weeded.

Very good predecessors

Good predecessors

Lollo biando / Lollo rosso

Bad predecessors

Good successors

Lollo biando / Lollo rosso

Bad successors

Crop rotation

What stood on that bed three years ago is hard to recall come spring. grove remembers. Once you have planned with it for a few seasons it knows your beds and warns you as you plant when a growing break is still running. The other way round, grove points you to the spots where Courgette fits particularly well right now.

As green manure before Courgette, grove suggests Lupin very good for example, provided the crop before it fits as well. As the crop before it, grove suggests Radish good, Pea good or Bush bean good. After it come Onion good, Carrot good or Kohlrabi good.

As a preceding crop: Cucumber poor, Squash poor, Sunflower poor and 2 more plants may only return to the same spot after 4 years. grove still remembers that three years from now. As a following crop: Cucumber poor, Squash poor, Watermelon poor and one more plant may only return to the same spot after 4 years.

And as soon as next year is planned, the Garden Fairy looks for the right green manure for the cold season in between all by itself, Phacelia for example. How the Garden Fairy works

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Care and fertilising

Courgettes are prone to mildew, both downy and powdery, so they benefit from a regular boost with horsetail tea or fermented horsetail, sprayed directly onto the leaves as well. Prepare the bed well with compost or manure before planting.

For a steady harvest and good-looking fruits, you need to water regularly.

Diseases and pests

From mid-July onwards, courgettes often show powdery mildew as a white coating that wipes off easily, first on the older leaves. The plants usually keep cropping anyway. Water in the morning and at the base of the plants so the foliage dries off quickly, and don't put new plants right next to older ones. Viruses such as zucchini yellow mosaic make the leaves mottled and the fruits lumpy. Aphids carry them from plant to plant, so a fine mesh net until flowering helps. Some varieties stand up better to mildew and viruses.

In wet weather, pumpkins and courgettes sometimes come down with gummy stem blight: the tissue at the base of the stem turns soft, a sticky sap oozes out, and small black dots appear. Cut out affected shoots straight away and always water at the base of the plant.

In cool, damp weather you may see cucumber scab and septoria leaf spot, so clear away affected plants completely in autumn. In spring and autumn, slugs and snails like to feed on young plants.

Susceptible to

Angular leaf spot

Bacterial leaf spot of cucurbits

Black root rot(low susceptibility)

Cucumber mosaic virus(resistant varieties available)

Cucumber scab

Cucurbit anthracnose

Cucurbit downy mildew(low susceptibility)

Cucurbit powdery mildew(medium susceptibility, resistant varieties available)

Gummy stem blight

Septoria leaf spot

Two-spotted spider mite

Watermelon mosaic virus(resistant varieties available)

White mould

Zucchini yellow mosaic virus(high susceptibility, resistant varieties available)

Harvest and processing

Harvest courgettes while they are still young, 10 to 25 cm is plenty. The bigger they get, the mushier and less tasty they become.

Watch out for bitter courgettes. Never eat them! The bitter compounds are toxic, cause vomiting and diarrhoea even in small amounts and can seriously damage the mucous membranes of your digestive tract.

Fruits can turn bitter if you use seeds from courgettes that grew next to ornamental gourds. Ornamental gourds often still carry plenty of these bitter compounds, which is why you must not eat them. If both grow too close together, the bitter compounds cross back in.

In longer dry spells the plants can also suddenly start producing these compounds again, out of stress.

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