Plastic greenhouse or Shade net greenhouse: Which one is the best?

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Plastic greenhouse or Shade net greenhouse: Which one is the best?

A greenhouse is a structure with walls and roof that is made of transparent material, such as glass or plastic, in which plants requiring regulated climatic conditions are grown. Its roof and sides have to allow light to penetrate.

The greenhouse heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building faster than heat can escape the structure. Greenhouses can also protect plants from: –
excess heat from the sun, too much wind, heavy rains and hailstorms, pests and animals, frost and many other natural disasters.

A greenhouse makes it possible to grow certain types of crops all year round. Tomatoes, bell peppers, also known as capsicums, fruits, vegetables, and flowers are what a greenhouse helps you grow all year round.

Tomatoes are the number-one greenhouse crop grown in most countries, probably because the demand is high and consistent throughout the year. Cucumbers are the second most popular greenhouse crop, followed by bell peppers.

Strictly speaking, a greenhouse has always been a glass house – the greenhouse whose roof and sides are made of glass. But then they are very expensive, and not everyone can afford them. That is why a cheaper version – that made of plastic – was invented. So the most common greenhouses are those made of glass and plastic. With the ever evolving technology and integrated research in the farming sector, many farmers, especially those who live in warm climatic areas such as Africa are now resorting to shade net greenhouses or simply shade houses. This is a special, yet simple and cheaper type of a greenhouse that is made of knitted or woven nylon cloth.

This lesson will teach you about a shade net greenhouse, while comparing it to a plastic greenhouse, which many farmers are used to, as it has been on the market for a very long time now.

Shade cloth greenhouses are used to protect cultivated plants from excessive heat, light or dryness. The shade cloth comes in different colours and percentages to protect plants from sun, frost, pests and the like. For horticultural projects such as green vegetables, tomatoes, English cucumbers, bell peppers, lettuce and the like, use a 40% white shade cloth. This is because most horticulture plants require only 60% of the sunlight. So, a 40% shade cloth will block 40% of the sunlight, thereby allowing your plants to enjoy the 60% sunlight that they require for optimum photosynthesis to take place, without losing a lot of water to evaporation and respiration.

Shade clothes typically reduce the light level by 75% and turn it into heat. The cloth acts as a solar collector, and temperature of the cloth is higher than temperature of the air, so the heat energy goes up. As it goes up, a process known as evaporative cooling takes place.

Let's start with the disadvantages of a shade net greenhouse, and these automatically become the advantages of a plastic greenhouse.

Number 1. When its raining, water gets into the shadenet greenhouse through the roof and also through the sides, where as in a plastic greenhouse there is no rain water that gets inside. However, in a shade net greenhouse water penetrates as little showers, and that's an advantage to the crops, because rain water is the best, and the showers will be very light, such that they wont splash any soil particles to the leaves, as these soil particles are the dangerous ones, they bring foliar diseases to your plant leaves. However, you can simply apply Copper Oxychloride or Mancozeb twice a week during the rainy season and your plants in the shade net will do just fine.

Number 2. During winter, temperatures in a shade house are quite lower than the temperatures you get in a plastic greenhouse. However, White reflects heat, so during the day the shade net greenhouse traps heat, and at night that heat gets released gradually over a period of time – that's why even at night in a shade net greenhouse, temperatures are much higher than those you get outside the shade net house. To add on to that, the height of a shade net greenhouse should always be above 3 metres or 9.9 feet, while that of a plastic is often around 2 to 2.5 metres high, that is 6.5 to 8.2 feet high. The height helps reduce chances of frost attack in winter.

Those are the only 2 disadvantages of a shade net greenhouse, but the first one is actually a blessing in disguise, you just have to apply Copper Oxychloride or Mancozeb twice a week during rainy season.

Now let me state and explain the advantages of a shade net greenhouse over a plastic greenhouse. Again, these advantages automatically become the disadvantages of using a plastic greenhouse.

Number 1. Its cheaper. In most countries, the total amount of money you part with to build a single plastic greenhouse, is usually double the amount you spend to construct a shade net greenhouse of the same size. This is because a shade cloth usually costs half the price of the same size of the plastic.

Number 2. You use less materials when constructing a shade net greenhouse as compared to a plastic greenhouse. A plastic greenhouse should never be flat shaped at the top. It has to be dome shaped or gabble shaped, so that when it's raining, the water will not form a puddle on the roof top. In contrast, a shade net greenhouse is flat shaped, if ever rain water gathers on top of the shade house, it will all gradually drip into the greenhouse – as little showers. This means that you save a lot of money on extra poles, extra steel bars and extra other materials used to make a special roof for the plastic greenhouse.

Number 3. Ask those who have a plastic greenhouse, they will tell you that it's next to impossible to go for 3 years without repairing the greenhouse – that is to put a new plastic. If ever your brand new plastic greenhouse gets subjected to a windstorm then that's game over. Heavy rains and hailstorm will likely leave your plastic greenhouse not very healthy, if not roofless. But that's a different story with a shade net greenhouse. A plastic greenhouse has a lifespan of 2 to 3 years, while a shade net greenhouse has a lifespan of 8 to 10 years – despite the fact that it's about 50% cheaper to construct a shade net greenhouse.

Number 4. In summer, a shade net greenhouse performs better than a plastic greenhouse, because the shade net material is full of small vents, so there is enough air flow to keep the temperatures optimum. It's strongly discouraged to grow peppers in a plastic greenhouse in summer, because bell peppers don't like heat, they don't like cold temperatures too but when one has a plastic greenhouse, it's a very bad idea to grow these capsicums in summer. As for tomatoes, in a plastic greenhouse some lose flowers, others wither due to high temperatures, so a farmer will have to irrigate the plastic greenhouse plants with lots of water to cool up the crops during very sunny days. On the other hand, in a shade net greenhouse you can grow peppers and tomatoes all year round, the temperatures are almost acceptable most of the time throughout the year.

Number 5. You can easily spend the whole day working in the shade net greenhouse, and you won't be inhaling dangerous gases or chemicals as is the case in a plastic greenhouse where ventilation is a real struggle. The shade net greenhouse has excellent ventilation and greenhouse workers will enjoy working in a shade net house where fresh air circulates throughout the day.

Number 6. Repairing a shade net greenhouse is near $0 cost. In the event that the shade cloth has torn up, you can easily stitch or sew the damaged part using the same twine and needle which you used to construct the greenhouse. But with a plastic greenhouse it's a different story, you will have to remove the whole plastic row on that section and replace with a new one.

Number 7. Temperature control in a shade net greenhouse is regulated automatically. During the day when it's very hot outside, get into a shade cloth greenhouse, you will be surprised to find some shade and better temperatures, even though it will be a bit warm inside. Come again in the evening, it will be very cold outside, but in the shade cloth greenhouse you will be greeted with some warm temperatures. On the contrary, with a plastic greenhouse, during the day, especially in summer, it will be very hot and you may easily sweat so much, crops will wilt and you will be forced to irrigate a lot so as to cool down the plants. Some plastic greenhouses have thermometers and air vents or portions covered with both plastic and shade cloth, so that when temperatures rise, the farmer opens the air vents or winds up the plastic that covers the shade cloth portion, as this will allow more air inflow to lower temperatures. All this means that there is more work for the farmer when using a plastic greenhouse as compared to a shade house.

So you have it guys. You are better off with a shade net greenhouse than a traditional plastic greenhouse, which is less durable, poorly ventilated, more expensive to build or repair and not great for heat-sensitive crops in summer. Want to build a greenhouse, go for a shade net greenhouse and enjoy farming for the next 10 years.