Polytunnel for beginners

Polytunnel for beginners

A polytunnel is a construction which optimizes production and provides larger yields. Although many documents, studies and offers present greenhouses as a wonderful solution for every gardener or farmer, remember that this can only be achieved with effective equipment. As with any tool, it is important to use them appropriately. Thanks to know how and common practices, success of the project will follow. The same rule applies for hobby and professional crops. Vegetables and fruits require a lot of work and labour in order to get more yield. Regardless of the level of knowledge, everyone is aware that several basic principles affect the development of plants.



It would be difficult to describe all the factors for good cultivation in one article. Although this is only part of a comprehensive subject, this represents a compilation of basic knowledge for gardening beginners , and a reminder of important issues for those already producing.

Effective and successful cultivation

Vegetables and fruits grow in an environment composed of two elements. The space above the ground where the plant develops is called the climate. The second element, where the root system spreads, can be either soil, specialized soil, water solution (hydroponics) or suspended (aeroponics).

Crop’s quality and yield

Cultivating methods and subsequent care of all plant’s parts have an impact on the crop’s quality and yield. When cultivating a specific variety, you first need to learn about their requirements and then adjust the environment in the greenhouse to be as accurate as possible. Thanks to this, the plant benefits from top conditions and grows, blossoms and produces fruits. Such activities require work before and during the growing season. Therefore, when deciding on species selection, it is important to  examine and identify the right site for the plantation. This way, the number of jobs will be reduced, and vegetables and fruits will avail of favorable factors, without the need for additional financial investment. It is worth remembering that throughout the plant growth process, conditions might change. Systematic control of the situation and appropriate actions will have a positive effect on yield.

Essential for photosynthesis

The term “climate” itself means a set of coexisting factors that govern  proper growth and development of vegetables and fruits. These factors include: light, temperature, precipitation, air composition, and microclimate produced directly by plants. The most important climatic factor is light. It provides the energy , essential for photosynthesis. Resulting from that process, organic substance and oxygen are formed. The glucose produced is later used for further processing by fruits and vegetables. Stored in stems and roots, it turns into starch or fat.

More light

In addition to the effect on photosynthesis, light acts on plant growth and development. This process is called photomorphenesis. Light regulates phenomena occurring in plants throughout their entire existence. It is important for maturation, germination, green mass production, flowering, fruiting and aging.

Vegetable and fruit blossoming depends on the group which they belong to, regardless of whether they are short or long day plants. Based on a 24 hour cycle, this phenomenon is recognized by observing how long the plant is able to grow for with constant access to light.

Low light intensity

Plants from different latitudes react differently to local climates. For example, kalelettuce, and arugula are shade loving types. Being adapted to low light intensity, they are successfully grown in shady environments. Thermophilic plants such as pepperstomatoes and zucchinis grow well with strong sunlight. In our latitude, light intensity significantly decreases at certain times of the year. In autumn and winter , exposure is too little to obtain full growth of plants with high light requirements. For this purpose, polytunnels, greenhouses, garden tents with artificial lighting are set up.


The next important factor for development of crop is temperature. Optimal temperature provides better and faster crop growth. Adequate levels might be required according to development phase as well as intensity of light. Different needs appear at specific stages of plant development like sprouting, flowering and fruiting.

minimum value

Vegetables and fruits have precise characteristics in relation with their species and some varieties are resistant to low temperatures. If the temperature drops below the minimum value, their growth is inhibited. The majority of crops do not grow below 5 ° C, although there are cases where some perennial vegetables are able to withstand even -20 ° C (kale, leek). Heat-loving plants such as cucumber, tomato, pepper are very sensitive to cold and temperatures below 0 can permanently damage them. If no suitable conditions are created during the various growth stages, the expected crop may not survive. They may not grow flowers, fruit or reach their shape in time.


Whatever the amount of precipitations, crop quality does not depend on quantity, but rather on composition and frequency. A regular lack of water will give a bitter and woody taste to your harvest. In contrast, excess will reduce the amount of dry matter, washes away nutrients and increase chances of pathogen infestation and attack by pests.
Although the cover does not allow rain in, using Irrigations systems will prove a reliable and regular source of water inside the greenhouse.
There are more or less easier ways to equip yourself  (diy drainage gutters for rainwater from a tank, mechanical installation with sprinklers, capillaries) and these systems are available for both small hobby tunnels and professional multi chapel structures.

watering levels

A greenhouse allows you to adjust watering levels to the area without generating aditional costs. This can be easily achieved by mounting moisture indicators available on the market. Private polytunnels are already equipped with such installations,and they are getting cheaper year after year.
Precipitations also include snow, which creates snow cover, and hail which occurs suddenly. In both cases, field crops are exposed to damage from these weather factors. The foil cover of the tunnel forms a protective shield over vegetables and fruits.


The air circulation under cover works favorably on the plantation. It dries out leaves, limiting the development of infections and fungal or mold diseases. Wind also supports self pollination of plants. However, it is destructive if the gusts are too strong. Overcrowded or damaged plants fall off, rotting on the ground. Horticultural tunnels prevent strong winds thanks to foil. Single or multi vegetation tunnels with side ventilation are equipped with a couple of doors, creating beneficial air movement inside the structure without negative consequences.

Positioning a tunnel

Plants with a delicate root system are particularly vulnerable to strong air movements. Cucumbers, beans, asparagus and clinging shrubs without proper protection may break. The conditions in the garden tunnel and the crops themselves are influenced by the location of such a structure. If it is located near a forest, the microclimate inside will be different than from an open field set up. Positioning a tunnel facing south guarantees much better soil heating, warmer air and longer exposure. The proximity of a large water reservoir will, however, affect the reduction of temperature differences between day and night. Do not expose your greenhouse to flooding by positionning it in holes but rather place it on light slopes for drying purposes.


Vegetables usually have high demands on soil. The earth can not be too heavy and too damp. Water content and nutrients are parameters that improve growth. The humus layer, no matter what the species and varieties, must have a thick layer from which the plants will extract micro- and macroelements. If the soil structure is lumpy, the nutritional and development processes will be much more favorable. The optimum soil PH for a large number of vegetables is 6.2 to 7.5. There are exceptions, of course, for which Ph needs to be matched. The most demanding are cauliflower, cucumber, celery, Chinese cabbage and onion. With soil care, you can expect to produce much better yields. Respecting the deadlines, completing tasks in due time, providing plants with nutrients through substrate fertiliation, these are the tasks for every gardener.
For this purpose, different farming tools are being used.


The correct plant rotation also has an impact on yield. Cultivation of the same species or plants from the same family generates soil fatigue, leadind to low yields. Diseases and pests that are common for the crops in question can develop and affect the plantation. Acidification or salinity are also consequences of a poor rotation. Post-season production sites must be cleaned, fertilized and previously harvested crops must be reallocated and replaced by other plants.


To expect top quality production, you have to satisfy plants’ nutritional needs. For this purpose, directly or indirectly, appropriate doses of mineral or organic fertilizers are introduced. A significant part of such elements for vegetables and fruits are taken from the soil. Every action should be preceded by soil analysis. This way , with the shortages in mind, you can optimally and advantageously enrich the soil. Basic soil analysis is a cheap service, yet this guarantees better harvest . Bad dosage, incorrect fertilization always leads to decrease in quantity and quality. Carbon, oxygen, hydrogen, phosphorus, potassium, nitrogen, calcium, magnesium and sulfur are the elements which play a major role in the growth process.
In smaller quantities,you can mention iron, manganese, zinc, copper, boron and chlorine. Not all ingredients are present in soil, and even if they are, they could be inaccessible by plants. To what extent will depend on the soil condition.

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