Salads growing under cover , among them mache, boston, frisee, rucola, butter, iceberg, roman, radicchio – are just a few varieties of Asteraceae family. Tasty and healthy, tempting with their appearance. Salads are a decoration for dishes and a source of vitamins and micronutrients necessary for a healthy diet. Growing them in a foil tunnel is very easy. This mini guide, we will talk about lettuce in tunnel step by step.
Cultivation of salad in a garden tunnel
Lettuce should be planted on soils with sand and clay, although growing is possible on almost any type of substrate. The sandy-dry ground structure is too demanding for the Asteraceae family, which includes lettuce. There is no high requirements for their positioning , growing in both sunlit and semi-shaded areas. Still , at the very beginning of growth, it needs to grow with a lot of light as it is a long day plant which means that for the development of inflorescences. It needs a minimum of 14 hours of light. Only the release of flowers is unfavorable. So optimum conditions will be obtained when the lettuce is exposed for 12 hours.
Importantly the taste of lettuce
On the market , there are many varieties that should be cultivated at specific times of the year and adjusted to the length of the day. The variations of the short and long days require to adjust the level of sun exposure; not providing them with the conditions needed will slow down their growth. To develop , lettuce need a relatively low temperature ; during high heat , good practice is to shade them. Quality and most importantly the taste of lettuce depend on the soil. So we plant them in a fertile and humid humus substrate to get the best and desired tender leaves. Sometimes, due to a short cultivation period. It is grown as a forecrop, a perennial or a post crop. Which is an opportunity to harvest several times a year.
Salads from seddlings in the foil greenhouse
We sow a type of lettuce for early harvest 6 weeks before putting it into the polytunnel. In the garden greenhouse, we sow them with a spacing of 5 cm or in pots every 5 cm. Allowing access to light for each plant.
Planting salads in polytunnel
As the lettuce is not so sensitive to low temperatures, we can start in the second half of March. The method of planting depends on its variety and the predisposition of growth. Due to the fact that early lettuces form smaller heads. We plant with a spacing of 25 X 30 and a 40 x 25 spacing for later varieties with longer leaves.
We plant in a way that the middle part of the leaf is not covered with earth. Remember also that asteraceae has a shallow root system and so it is not recommended to plant it in the company of deep root vegetables. The most harmful and damaging pests for gardeners are snails. Garden tunnel with a well buried foil will not let the mollusks in. However, if they ever get inside, check the tightness of the side walls and set out traps.
Care of salads in the garden tunnel
Systematic care of lettuce consists in irrigation and removing weeds. The superficial root system means no high water requirements, but be careful not to water the leaves as this can lead to rotting and broken heads. If you want to accelerate or extend the production. You can cover it with an agro textile or specialised foil. It will retain warmth in the soil and will therefore improve plant growth.
Concerning the soil for lettuce in a greenhouse, it could be sprayed with green manure with the addition of chicken manure ; we can prepare it ourselves or buy it ready in bags.
Variety of lettuce for polytunnels
Within the varieties of lettuce, differences can be found with shape, size, color of the head. Additionally we can divide them into early, medium early , medium late and late. A few of them are listed below:
Butterhead lettuce – most often cultivated on plots, gardens and foil tunnels, characterized by delicate leaves.
- Iceberg lettuce – a variety with stiff, crispy leaves that are slightly crinkled.
- Roman lettuce – oval heads full of fragile, slightly elongated leaves.
- Chicory – Late variety often cultivated in a fallow, harvested late in the fall or just before winter.
- Rosette lettuce – a very delicate variety that does not develop tight head, should be eaten quickly due to its fragile nature.
- Batavian – a variety of notched leaves, resistant to frost, which is cultivated until late autumn.
Harvesting and storage of lettuce
The harvest depends on the variety and planting date. The lettuce is collected early in the morning, the leaves are stronger and less vulnerable at that time. To keep the lettuce stable, we keep it at 0°C, with humidity up to 90%.