Polytunnel

A polytunnel is a tunnel made of polyethylene, usually semi-circular, square or elongated in shape. The interior 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. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. Temperature, humidity and ventilation can be controlled by equipment fixed in the polytunnel.

The idea temperature in the polytunnel is between 23º and 25º. At higher temperatures the fungus will grow and attack the plants.

Apart from special equipment we can modify the temperature and the humidity inside the polytunnel using very simple techniques.

To lower the temperature we can:

- Paint the glasses in white to

- Open the doors

To raise the temperature we can:

- Put the blinds in the evening

- Place a reflecting blanket

- Use a propane burner

- Place hot-water pipes

- Place red lamps

If we are building a green house we can build the south face with brick as it will retain the heat inside them and the north side with stone to avoid loosing the temperature on that side.

If we need to lower the humidity inside the polytunnel we will open both ends of the tunnel to circulate the air.

Courgettes

Courgettes are also called zucchini. 

In a culinary context, the courgette is treated as a vegetable, which means it is usually cooked and presented as a savory dish or accompaniment. Botanically, however, the zucchini is an immature fruit, being the swollen ovary of the zucchini flower.

Courgette is one of the easiest fruits to cultivate in temperate climates. As such, it has a reputation among home gardeners for overwhelming production. One good way to control over-abundance is to harvest the flowers, which are an expensive delicacy in markets because of the difficulty in storing and transporting them. The male flower is borne on the end of a stalk and is longer lived.

While easy to grow, courgettes, like all squash, requires plentiful bees for pollination. In areas of pollinator decline or high pesticide use, such as mosquito-spray districts, gardeners often experience fruit abortion, where the fruit begins to grow, then dries or rots. This is due to an insufficient number of pollen grains delivered to the female flower. It can be corrected by hand pollination or by increasing the bee population.

The courgettes need a neutral high rich organic soil. They need warmth and shelter so in Ireland it is a good option to plant them inside the polytunnel.