How to grow courgettes

Learning to grow your own courgettes. Tips and helpful information.

The courgette is a vegetable which belongs to the family Cucurbitaceae and is known scientifically as Cucurbita pepo.

It is an annual herbaceous plant with compact foliage and an indefinite growth rate.

The root system consists in a main root which reaches an extensive growth rate when compared to the secondary roots which only spread out superficially.

It possesses a main stalk from which secondary stalks grow but they will wither unless pruning is carried out in order to induce them to branch out into two or more stems.

The plant can reach up to more than a metre in length; it is thick and cylindrical in shape, with a prickly surface which is rough to the touch. It possesses a series of short internodes, from which the leaves, flowers, fruits and various thorns sprout.

The leaves are palm−shaped, green in colour, they are held up by long strong petiole, which sprout directly from the stalk, alternately and in a spiral fashion.

The blade is large with a glabrous shaft and a rough underside which is covered in prickly hairs.

The flowers are large solitary axillary blooms which are bell−shaped and yellow in colour. They can be either masculine or feminine, both sexes coexisting separately on the same monoicous plant.

The calyx consists of five pointed green sepals. The corolla is made up of five yellow petals.

The fruit is fleshy pepo which is unilocular without a central cavity, variable in colour, and it might be smooth, stripy or mottled.

The seeds are a yellowish-white colour, elongated and oval in shape with a pointed tip. They are smooth with a groove along the length of the seed, which is parallel to the outside edge.

The courgette is not particularly demanding as regards temperature requirements; in fact it is less demanding than the melon, the cucumber and the water melon.

The optimum temperature for vegetative growth is between 25ºC and 30ºC and during the flowering stage this will vary between 20⁰C throughout the night and 25ºC during the day.

The optimum relative humidity of the air in the greenhouse will vary between 65% and 80%.

The bushy foliage of the plant and the high water content of the fruit, make it obvious that the crop in question will require plenty of water; this means it will need to be watered on a regular basis.

As far as the courgette is concerned, the length of daylight will not have excessive repercussions on plant growth as there do not tend to be any problems with regard to flowering. Due to this fact, courgettes can be grown in greenhouses at any time of the year. However, sunlight will aid photosynthesis and will also play a part in maturing the fruits and in their earliness.

The courgette easily adapts to all types of soil, although loamy, deep, well drained soils are the most recommended.

Nevertheless, the courgette is very demanding where the intake of organic materials is concerned.

The optimum pH level of the soil varies between pH 5,6 and pH 6,8 although the courgette can adapt to soils with levels between pH 5 and pH 7.

This is a species which is fairly tolerant towards to both soil salinity and the water used for irrigation purposes; it is however, less tolerant than the melon and the water melon and more tolerant than the cucumber.

The planting of courgette plants in greenhouses is carried out with seedlings taken from seedbeds once they have produced between 2 and 3 well established leaves.

In order for transplanting to take place, holes are made in the soil and once the root ball is placed into the hole, it is covered and watered so the plant takes a firm foothold with regard to the root taking process.

Each plant should normally be positioned at a proximity of 1 plant m²; however the settings for planting are usually 2m×0,75m, 1m×1m, 1,33m×1m and 1,5m×0,75m.

The growth and development of the plant takes place via the main stalk, pruning is limited to the removal of the occasional side shoot.

Staking and tying the plants will ensure the upright growth of the stalk and will prevent the trailing stems from lying on the ground. It will also improve the general aeration of the plants and will make it easier to take advantage of sunlight and to undertake all of the care necessary with relation to crop production.

In order for the fruit to grow correctly, the implementation of phytoregulators is still the predominant choice although natural pollinators such as bees and bumblebees are being used more and more.

The courgette is a plant which requires high levels of moisture. This means that frequent watering will be necessary once the first fruits appear. However, if the ground becomes waterlogged, this will have an adverse effect.

With regard to feeding and nutrition, it would be recommendable to maintain the ratio of N−P−K to 2−1−2,5. It is also vitally important to plant nutrition to take into account that the plants will require an adequate supply of micro−nutrients.

The main plagues seen to affect the courgette have been found to be whitefly, thrips, red spider-mite, aphids, leafminer and slugs. The most notable diseases are powdery mildew, grey rot and mildew.

With respect to virus infections, those which should be emphasized are; the zucchini yellow mosaic virus, the cucumber mosaic virus, the water melon mosaic virus and the cucumber vein yellowing virus.

The time period from the point of first fruit emergence to harvesting the crop will vary between 30 to 40 days. However if the plants are in the open air and subject to adverse climatic conditions, the aforementioned time may well be prolonged.

When the plants are in full growth and production phase harvesting usually takes place on a daily basis. Meanwhile, at the end of the production cycle, the frequency of harvesting will decrease to the point where the fruit will be cut from the plants every 3 or 5 days.

The fruits are usually harvested whilst still slightly unripe, close to full growth but prior to full seed development and before they harden.

Harvesting is carried out by making a clean cut to the stalk with scissors or a knife, ensuring that 1cm to 3cm of the stalk still remains attached to the fruit.