The mighty spud – the potato

Alongside rice, wheat and maize, the potato is one of the world’s most important staple foods. Potatoes are rich in starch and minerals and can be used in a wide variety of dishes.

The potato originates from South America, where the first tubers were discovered more than 7,000 years ago in the Andes mountains by the ancestors of the Incas. Spanish conquistadors brought it to Europe in the 16th century. Today, there are more than 5,000 varieties worldwide, but only a small number are of significance in Luxembourg.

Because of its distinctive shape, the potato used to be called “Erdapfel” (earth apple) or “Grundbirne” (ground pear) in German, the latter giving rise to the Luxembourgish term “Gromper”.

For planting, the soil temperature should be above 8 °C, as this is when potatoes germinate best. Potato plants need warmth to grow and cannot tolerate frost at all. This is why seed potatoes are planted in the soil from April to early May using a planting machine.

The machine then piles plenty of soil over the tubers, forming rows of mounds known as ridges. Although potatoes can also be planted in flat beds, ridge cultivation offers several advantages: potatoes prefer warmth, moderate moisture (not too dry, not too wet) and complete darkness. The loose soil of the ridges warms up more quickly, dries out faster and prevents waterlogging. In addition, potatoes grown in ridges are easier to harvest with machinery.

In the weeks that follow, the seed potato develops roots and numerous side shoots underground. Thickened ends form on these shoots and gradually develop into potatoes. Above ground, a leafy plant grows, reaching up to a metre in height and producing white or purple flowers. When the above-ground part of the plant wilts or is removed in late August or early September, the tubers stop growing and develop a firm skin. Three weeks later, they can be harvested using a potato harvester. This machine lifts the entire ridge – soil, tubers and foliage – and harvest workers usually remove stones and any rotten, green or damaged tubers by hand. The potatoes are then transported to storage.

One important factor in distinguishing between different potato varieties is the length of time they take to grow.

  • Very early to early varieties take 90–120 days to mature (time to maturity). They are harvested from August onwards. Examples include Annabelle, Ukama, Belana, Glorietta, Goldmarie and Linda.
  • Mid- to late-season varieties take around 120–140 days to mature after planting and are typically ready to harvest from the end of August onwards. Examples include Victoria, Nicola, Laura, Désirée, Annalena and Emanuelle.

Potato varieties are moreover classified as waxy, all-rounders or floury. Floury potatoes have a higher starch content (around 18%), while waxy varieties contain about 12%. Starch is the plant’s nutrient reserve.

  • Floury varieties are ideal for turning into dishes such as mashed potatoes, gratin, gnocchi, croquettes, dumplings, French fries and crisps. Examples include Victoria, Jelly, Ukama and Désirée.
  • All-rounder varieties are well suited for boiled potatoes, fried potatoes and potato pancakes. They include Belana, Nicola and Anuschka.
  • Waxy varieties are ideal for potato salad and potatoes boiled in their skins, such as Annabelle, Glorietta and Linda.

In Luxembourg, seed potatoes – known in Luxembourgish as “Setzgromperen” – are produced alongside table potatoes. While table potatoes are cultivated to produce medium to large tubers, the aim with seed potatoes is to produce smaller tubers, but in the greatest possible quantity. Smaller tubers are easier to transport and plant by machine. For this reason, the mother tubers for seed potato production are planted closer together. During cultivation, great importance is attached to plant health: The farmer must protect the crops as effectively as possible from diseases and pests, and remove any diseased plants from the field. Government inspectors carry out checks and take samples for laboratory testing. The aim is for the seed potatoes to grow into healthy, vigorous plants for table potato production. Luxembourg seed potatoes are sold to many countries, particularly in southern Europe and the Mediterranean region.