Asparagus cultivation in a polytunnel

Asparagus, compared to other vegetables, can grow year on year even for 15 years! This property gave asparagus its reputation as a perennial plant. Green asparagus shoots have many medicinal properties, are healthy and are considered one of the most effective aphrodisiacs. However, it is important to understand that harvest will only be possible after several seasons. So start to cultivate as soon as possible to enjoy the amazing taste of fully grown asparagus.
Only fully mature plants are harvested. With the arrival of spring, young shoots appear out of the ground. When they reach a height of 20 cm and a diameter of 3 cm, they are ready to be picked. Fresh asparagus is best, so process them in the kitchen straight from the polytunnel to cook various tasty dishes.

Soil for growing asparagus

For the optimal substrate, soil will be neutral or slightly alkaline, with a pH of 6 to 7.5. In addition, it should be light so that the fine shoots easily emerge from the ground, permeable and moderately damp. It can not be too damp, as it leads to rot, which then causes fungal infections and death.

Positioning

Asparagus are light-loving plants, so they are planted facing south. Constant access to light and a warm soil gives them good conditions to ripen. However, avoid overheating and a temperature exceeding 25 degrees celsius in the greenhouse. During heat waves, opening the tunnel side ventilation is a good solution and allows temperature control. With the “curtains” raised, air circulates and excess heat is released. Low spring temperatures in open field production slows down growth of asparagus and the vegetable becomes harder, bitter and fibrous. Therefore, growing them under small polytunnels gives better results. This also protects asparagus from gusty winds, which could break fragile shoots.

How to grow asparagus?

For the plant to grow much faster and benefit from the right conditions during the early stages of growth, it is necessary to prepare the area before planting. If proper care is carried out throughout the whole season, yield will develop twice as fast. Seed sowing takes too long, so it is advisable to buy asparagus crowns to be planted in a small polytunnel.

  • Step I:

Asparagus are planted in lines , with a spacing of 120 cm between each row. It is one of the most commonly used practices. Weeds growing in the area should be removed mechanically or with herbicide. You can also spread agro textile, leaving just the top of the plant to emerge.

  • Step 2:

The soil should receive a minimum 8 cm layer of organic matter on a width of up to 45 cm. The best choice will be composting manure or humus. When the soil meets the requirements, it is almost ready for asparagus. However, if the pH value is below 6-7.5, liming of the substrate can be carried out. It is best to know the soil’s mineral content. With this knowledge, it is possible to enrich the soil with the required elements.

  • Step 3:

In the winter, the soil is mulched or used to intercrop

  • Step 4:

Just after the last strong frosts, a trench is dug with a depth of 20 cm and the length of the line. In it, we plant the seedlings, placing them every 35 cm.

If you carefully follow each of these steps, you will see yields within two growing seasons. Be patient and do not cut the first shoots, even if they are tempting . Giving them time to develop, they will get tastier and more abundant the following season.

Varieties of asparagus

Methods of cultivation are quite different depending on the variety, but stages of caring work remain the same. These are essentials because the plant can grow for many years. The plant can be divided into two groups: male as well as hybrids. Male have higher yields, but also higher soil requirements and require more time. The advantage of growing them is that they sporadically produce seeds, so crop will be less affected by annual seedlings. Hybrids varieties have different characteristics, are less demanding, more resistant and have lower soil requirements.

White and green

These are not species of asparagus or variety, their production depends on the method of cultivation. The white ones ripen into the ground. When they emerge, spikes are cut with a sharp knife and then stored in a dark, cold place. Such harvests are carried out in the morning and in the evening, twice during the day. White asparagus is thicker and compact, giving more yield, but less vitamins and minerals. Make sure you rinse the vegetable and cook it until soft.

Green asparagus grows above the ground. With greater access to light, they contain far more vitamins and nutrients. They are collected when they reach 20 cm in height, preferably during the afternoon. Do not cut them during cold days as each wound would be exposed to  humidity. Green asparagus produces less than white asparagus and is also less resistant to storage.

When to pick asparagus?

The season for asparagus lasts 6 weeks, starting at the beginning of May, ending in June. Apart from kale and spinach, it is one of the earliest plants to harvest. Shoots are cut with a knife below the ground, but be careful not to damage the rising stalks. As the asparagus grows foliage and begin to open, the shoots get hard and less tasty. You can avoid this by harvesting every two days. Those that have matured too long should be discarded because they are not suitable for consumption.

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