Grow cucumbers in the greenhouse – Complete Guide

Cucumbers are among the most popular vegetables in our gardens. With a little skill, we can grow and harvest cucumbers in greenhouses all year round. You also want to grow cucumbers in the greenhouse? This in-depth article will give you a concise summary of all the important aspects of growing cucumbers in a greenhouse.

What are the ecological requests for growing cucumbers in a greenhouse?

In greenhouse cultivation, some factors are very important to grow cucumbers in the greenhouse successfully. These factors are for example humidity, temperature, light, and air movement. These measures have to be adjusted very well. Be aware that these factors are in close relationship with each other and cannot be seen separated. That’s why you should know, which conditions are necessary for your greenhouse cucumbers to grow as you wish healthily. This in-depth article will guide you with all kinds of information to start growing your cucumbers in the greenhouse.

By the way, you want to know how to set up a greenhouse from scratch? In this article, you will find all answers to your questions: Setting up a greenhouse – what to know before starting

What botanical properties do greenhouse cucumbers have?

Greenhouse cucumbers have the following botanical properties:

• The main root is taproot and has a length of 5-10 cm.
• Roots do not go deep and spread to the sides up to 50-100 cm depending on the growth of the plant in the upper layers of the soil.
• Since it loves soil moisture very much, its roots grow superficially and develop at a depth of 20-25 cm under suitable conditions.
• Abundant lateral roots are formed from the main root.
• Depending on the soil structure, it can go down to a depth of 100-200 cm in sandy and light soils, and 50-100 cm in clayey and heavy soils.
• 60-70% of the roots are 10-20 cm deep in the soil.

The best cucumbers to grow in the greenhouse

The variety to be grown in the greenhouse is desired to be productive, early, and resistant to diseases and pests. Therefore, hybrid varieties are commonly preferred. The growing period also affects the choice of variety.

In greenhouse cucumber cultivation, it is suitable to use parthenocarpic varieties that only produce female flowers and do not require fertilization. You can grow these varieties earlier and the fruit quality is high.

Again in the selection of varieties, you can choose one that does not form side shoots, but produce many flowers and fruits in the nodes on the main stem.

Three main types can be mentioned according to the fruit types of cucumber varieties.

• Almond type (8-10 cm)
• Short (15-20 cm)
• Long (Langa) (25-40 cm)

Here are a few more specific examples:

• Helena: a biodynamic new breed that develops long, smooth fruits with a medium to dark green color. The fruits have a fine taste. The plant is a virgin variety, which means that each flower sets a fruit.
• Dominica is a purely female flowering variety that develops almost no bitter substances and is also resistant to diseases such as powdery mildew. The fruits become quite long at 25 to 35 centimeters.
• Eiffel is a robust F1 variety, the fruits of which are up to 35 centimeters long.
• Conquerer is an old greenhouse variety that can withstand lower temperatures than other cucumber varieties. Relatively large, aromatic, and medium green fruits are formed.

Growing periods in greenhouse cucumber cultivation

Cucumber cultivation is carried out in different periods according to the climate structure of the region where the greenhouse is located. To grow cucumbers in the greenhouse, the structure of the greenhouse, and which form of cultivation you want to choose is also important. These can be autumn, spring, single crop, late autumn, early spring, or summer cultivation.

In the table below, you can find specific growth periods of greenhouse cucumbers:

Growth Period	Seed Planting	Planting	First Harvest	Last Harvest
Single Crop	October 1 – October 15	November 1 – November 15	December 15 – January 1	30 June-15 July
Autumn	1 August – 1 September	September 1 – October 1	October 1 – November 1	January 1 – February 1
Spring	January 1 – January 15	February 15-March 1	April 1 – April 15	1 July-

What are the temperature requirements for growing cucumbers in a greenhouse?

Like other greenhouse vegetables like pepper, tomatoes, and eggplants, the most important environmental factor for cucumbers is air temperature. It is affecting vegetative growth, flower formation, fruit development, and quality. Cucumber is a heat-loving plant. It gets cold between 0.5° C and 5° C, and freezes at -2° C.

Although germination of cucumber seeds starts at 12° C, the temperature should be 27° C for optimal germination. Increasing the temperature above 30° C also negatively affects germination.

In the table below, you can see the ideal temperatures for growing cucumbers in your greenhouse:

Growth Period	Night	Day
Germination	27	27
Seedling Period – Planting	19	21
Planting – Harvesting	19	21
Harvesting Period	16	19

Lighting for the cucumbers in the greenhouse

Another important factor is lighting. The optimal light requirement is 15000 lux and the light requirement is about 14 hours. As in all greenhouse products, the relationship between light and temperature should be considered in cucumber cultivation, the temperature should be decreased when the light is low, and it should be increased when the light is high.

How to prepare the soil before planting?

To prepare the soil for planting cucumber in the greenhouse, factors such as soil character, watering, and cultivation methods should be taken into consideration. For cucumber roots to develop easily, the soil must be well ventilated. Process the soil while it is in full annealing. Therefore, if necessary, water the soil first and then plow immediately as soon as the soil pan arrives. 

Furthermore, careful harrowing is done to ensure that the clods are crumbled and the various plant residues on the soil surface are removed. In this way, the soil becomes ready for planting and you can water the plants more easily.

What are the soil requirements of cucumbers grown in greenhouses?

Greenhouse cucumbers like coarse, well-drained, warm, and airy soils. You will have advantages if the soil is rich in nutrients with high water holding capacity. Cucumber plant likes neutral or slightly alkaline soils. Soil pH should be between 6 and 8.

Growing seedlings for greenhouse cucumbers

If you don’t want to buy seedlings and grow seedlings yourself, many alternatives can be used for seedling growing purposes. However, the airy and high water holding capacity of the environment are two important features. For this purpose, it is recommended to use only peat or peat mixes (such as peat + perlite).

In preparing the seedling mortar, prepare farm manure, soil and sand correctly. In this process, the mortar to be disinfected is started to seed planting with the preparation of the mortar.

Starting in February, you can plant the seeds in a pillow or tube to expect healthy seedlings. 

Cucumbers are sensitive plants for displacement. At this point, to strengthen the plants, throwing 2-3 more seeds for each planting will be a good idea.

Seed sowing depth is approximately 1 cm. If planted deeply, the seeds may rot or if the environment is not optimized, the cotyledon leaves cannot rise above the environment and the rootlets may break. By planting superficially and the seed germinates, the seed coat remains like a hat on the cotyledon leaves, and the cotyledon leaves are damaged. Be aware that cotyledon leaves feed the plant until the first true leaf appears.

Preparing the greenhouse for planting cucumbers

If the greenhouse to be planted is previously used, it should be cleaned from the wastes of the previous period product and washed abundantly by ponding, because the cucumber plant is very sensitive to salinity. The soil should be plowed deeply, if the plow base is formed, this base should be broken. 8-10 tons of burnt farm manure per decare should be given to increase the amount of organic matter and improve the physical and chemical structure of the soil.

Soil should be disinfected for disease factors contaminated from the previous period in the soil. Nowadays, as the harm of chemical disinfection to human and environmental health is understood, some chemicals for disinfection have been banned. Currently, the most practical, effective, and healthy way is solarization using solar energy.

Solarization is the process of heating the soil in July-August, when the solar radiation is the highest in the summer period, after processing the soil in its annealing, covering it with a clean thin transparent polyethylene cover, closing all the ventilation openings of the greenhouse for about 45-60 days, thus raising the temperature of the soil and destroying diseases and pests.

After all these processes, soil analysis should be done and a fertilization program should be prepared. Potassium is especially important in cucumber cultivation. The effects of potassium on fruit quality, resistance to disease-pests, and fruit quality are very high.

Planting cucumbers in a greenhouse

In cucumber cultivation, better plant growth is observed if the planting is done on the soil embankments prepared 15-20 cm above the ground. Because the soil warms up more than planting outside, the soil of the root part of the plant is less crushed and the drainage of the excess water becomes easier, so the soil gains an airy structure. Choose the direction of the rows of your plants in the north-south direction for the plants to benefit from better lighting.

Planting can be done in a single row or double row planting. The important point during planting is that the humidity of the greenhouse soil should be sufficient and the planting should be done high. In other words, the seedling mortar should be made slightly above the soil level, and the water to be given later should not touch the root throat. This is especially important for planting in cold times. In hot times, planting should be done in the evening, and adaptation of the seedlings to the greenhouse should be facilitated.

How to hang the cucumber plant

About a week after planting, leeches on the stem begin to grow and start looking for a place to hug. At this stage, the plant has begun to take root in the soil. 

From now on follow these steps:

• Remove the cotyledon leaves on the plant – Because now the real leaves are coming out, the task of the cotyledon leaves is finished, they will dry in the future and may cause diseases.
• After this process, you can begin with the hanging

Thick cotton threads or nylon ropes are used to hang the plants. Since the body of the cucumber is quite brittle and prone to breakage, be very careful at this process.

Furthermore, to hang the cucumber plants, a wire or thick rope is pulled along the plant row at a height of 10-15 cm from the ground. A hanging rope for each plant is tied between this wire and the hanging wire above, and the plants are grown by wrapping it on this rope.

How to prune cucumbers grown in greenhouses?

As we also know it from greenhouse tomatoes or peppers, pruning is an absolute necessity in greenhouse cultivation. We prune differently depending on whether the varieties are mono-yield or multi-yield. In both plants, the seat shoots in the seats of the leaves in the nodes in the first 30-35 cm from the soil should be cleaned.

The reason for cleaning the seats in the first 30-35 cm section below is to provide good, strong plant growth. If there are any, the flowers that have formed should be removed. In mono-productive varieties, seat shoots are pruned from the 2nd or 3rd leaf seat according to the growth power of the plant. After the 6th node, we can hit the hill and stop the growth, or the free growth of the plant can be allowed for 6 months in single crop cultivation. 

After a certain time, you will realize that the underlying leaves start to turn yellow. If they grow too large, they must be cleaned to prevent excessive consumption of nutrients.

Fertilization in greenhouse cucumber cultivation

The cucumber plant is a plant that likes water and balanced fertilization. Therefore, add animal manure to the greenhouse before planting. Cucumber plant likes soil with high organic matter, the animal manure thrown away meets this organic matter requirement. Consider giving plenty of water immediately after planting. If the weather is extremely hot, watering can be done little by little every day.

The first fertilization is made with fertilizers weighing phosphorus 7-10 days after the life water. Besides this fertilizer, trace elements and humic acid are also added. Thus, the plant reaches the nutrients more easily and the salinity rate of the soil decreases. 

When fruit formation begins, potassium and calcium fertilization is started. Since cucumber is a productive plant, it consumes more potassium fertilizer. If the plant is deficient in potassium or cannot get this fertilizer, the fruits will begin to form a trapezoid. This will reduce the quality and flavor of the fruit.

Pollination of greenhouse cucumbers

Pollination of cucumbers in the greenhouse can be done in two ways – natural and artificial insemination.

While it is not always possible to use insect crafting in a confined space, it is quite possible to get most workers accustomed to the movement of pollen. In summer, at least where the greenhouse is located, you can allow pollinators using the ventilation system.

Artificial pollination is required:

• in a period of reduced insect activity
• during reproductive activities that require the exclusion of random fertilization
• Failure to provide pollinators access to the greenhouse

The best option is natural pollination as usual.

How the watering is done

The Cucumber plant needs a lot of water. It consumes 2.5-4 liters of water per square meter under high temperature and light conditions. Although it is a vegetable that likes water, it has a very small root structure with a width of 20-50 cm and a depth of 10-30 cm in greenhouse conditions. Due to its superficial and small root structure, the plant cannot benefit from the water given more than once, therefore the principle of less water – frequent water should be applied.

The ideal irrigation system for cucumber plants is the drip irrigation system. Watering should be done daily and, if possible, several times during the day. Cucumber is very sensitive to salt, so it is necessary to examine the salt content of the irrigation water well.

Harvest time of the first cucumbers

Although it differs according to the variety, it is harvested when it reaches a length of 10-30 cm. If the fruits are not harvested, they are large, yellow-rinded, hard, and even the top cracks, and the bright skin color disappears.

Harvesting is done by cutting the fruit stem with a sharp knife or scissors or by grabbing the fruit and lifting it and tearing the fruit stem from where it connects to the stem. The fruit should not be pulled down and plucked. Otherwise, the plant will be damaged and the fruit will not break with the stem, but the bottom of the fruit will be ruptured. This causes a decrease in fruit quality.

Harvest should be done early in the morning before the weather gets warmer. Harvested cucumber fruits should be stored separately from products that secrete ethylene such as apples and tomatoes. Otherwise, the shelf life of cucumber fruits will be shortened.

Now it’s your turn! Grow your own cucumbers in your greenhouse.