How To Grow Potatoes
The potato (Solanum tuberosum) is a useful plant and comes from the nightshade family (Solanaceae). When you say potato, you usually mean the plant’s edible underground root bulb. As numerous as the varieties of potato are, as regionally and dialectally different are their names: In French (“pomme de terre”) as well as in some regions in Germany it is called Erdapfel. In addition, the designations earth pear, Grumbeer, shockers or mice are common. In her homeland – the Andes highlands – she is called “papa”. In Peru and Bolivia, the potato used to be the main food of the Incas.
The United States largest consumer of potatoes in the world by 2020.
The success story of the popular tuber is closely linked to colonial history, as Spanish conquerors imported the potato into the “Old World”. Since the Spaniards confused it with the sweet potato, the “batate”, the Spanish word “patata” was used as a substitute for both crops and only later was a distinction made between “patata”, the potato, and “batata”, the sweet potato. The colonialists brought the plant to the Spanish mainland via the Canary Islands, where it was first recorded in 1573. From there, the potato slowly spread to Europe, where it was first planted as an ornamental due to its flowering.
Large-scale cultivation in Germany, to put an example of another country, did not take place until the 18th century. Frederick the Great, among others, contributed to its popularization and recognized its value as a staple food for his soldiers. Since it became more and more popular in the 19th century with the beginning of industrialization, it gradually displaced grain. The lack of alternative crops led to one of the worst famines in Ireland: in 1845, two million people starved to death in Ireland because for years only potatoes had been grown and the potato rot had destroyed much of the harvest. Although the consumption of potatoes has decreased compared to the beginning of the 19th century, there is still an annual average consumption of 50 kilograms of potatoes in Germany today – half of which is eaten in processed form.
Appearance and growth
Botanically, the potato is an upright and up to one metre tall herbaceous plant. From June to August, their white, pink-coloured or violet five-country-flowers with yellow anthers appear on the above-ground foliage-shoots with feathered leaves, from which cherry-size, green and inedible berries form. Underground, new nodules are formed, which are connected to the root sprouts by carrying threads, so-called stolons. The tubers serve as nutrient storage. Depending on the variety, the tuber shape is round, oval or elongated. The colour of the flesh varies from white and yellow to blue and violet.
Location and soil
Potatoes thrive on light to medium-heavy, deep soils without waterlogging. Although they can cope on barren soils, they prefer nutrient-rich beds enriched with mature manure and compost. However, yields on poor soils are lower. Ideally, the vegetable bed should be sunny.
Crop rotation and mixed cultivation
Since potatoes leave a good soil, they are an optimal pre-culture for all types of vegetables. Potatoes should only be grown on the same parcel every four years. Regular crop rotation and a versatile mixed culture, for example with carrots, thick beans or parsnips, are important. Potatoes and tomatoes should not be grown in the immediate vicinity in order to avoid the transmission of diseases, in particular late blight. Mustard and oil radish are suitable as green fertilizers for post-cultivation.
Potatoes can be sown and planted. When sowing the potatoes, it should be borne in mind that the seedlings are no longer identical with the mother plant and therefore new shapes and colours may appear. The advantage of sowing is that it enables the otherwise frequent viral diseases to be contained. You can harvest the seeds from the berries as soon as they are soft. After these two months have matured, they can be taken out, cleaned and dried. From February the seeds can be sown on the windowsill at 18 to 20 degrees Celsius. Then prick the young plants into small pots. According to the ice saints, they can go into the bed – in such a way that the root ball lies about 20 centimetres below the ground.
Planting potatoes is the far more common method. The timing of potato planting varies from region to region and from variety to variety. While in mild regions early varieties are already planted from the beginning of April, in mountain regions they are maintained until the beginning of May. In any case, the ground should have warmed to nine degrees Celsius. Potatoes can also be grown as a first crop on land as they have a soil-improving effect. If the area has just been cleared, you can keep weeds in check by frequently chopping and piling up.
If you want to harvest early, you can germinate your potatoes as early as March. To do this, place medium-size tubers up to half in flat boxes filled with potting soil and place them in a warm place of about 15 degrees – preferably in a light greenhouse or winter garden – so that short, strong shoots form. After about six weeks, the potatoes are carefully planted to a depth of about ten centimetres in the open-air bed.
In addition to the early harvest date at the end of June, pregerminated potatoes have other advantages: Even in cool weather, the plants continue to grow and ripen before the blight spreads. The yield is thus about 20 percent higher.
Before planting, dig the ground with a digging fork or a spade. A well prepared soil should be moist, loose and free of weeds. Then tighten a planting string so that the rows of potatoes are as straight as possible and all plants have the same area available. Use a hoe to draw a 10 to 20 centimetre deep planting groove.
The distance between the rows should be at least 50 centimetres. Add a good layer of compost, horn flour or horn shavings to the planting pit, press the pregerminated tubers slightly into the soil at a distance of 30 to 35 centimetres and close the planting pits with the rake.
In small beds, four to five tubers are calculated per square metre. Any loosened, weed-free garden soil is suitable. As strong eaters, potatoes are happy to receive a gift of extra compost or a handful of horn flour or horn shavings in the planting hole. After two to three weeks the first green appears. If you don’t have a garden, you can also grow potatoes in a tub or in a special potato plant bag on the balcony. Tip: Place only one tuber per container, this brings a better yield. Potatoes love damp soil, but not stagnant moisture. Drainage holes and gravel drainage are therefore a must.
Since potatoes are root crops, they must be chopped and piled up regularly, at the latest when the first green in the bed appears after two to three weeks. This ensures that the soil is loose and free of weeds, so that the plants develop many thick tubers. Alternatively, the tubers can be covered with a 20 centimetre thick mulch layer – this promotes the formation of microorganisms. When tuber formation begins, especially in the first three weeks after flowering, you should water the tubers generously in the morning so that the risk of late blight remains low. All in all, potatoes are modest when it comes to fertilization. Manure can already be spread on the bed in autumn, but it is better to fertilize sparingly because too much nitrogen makes the plants more susceptible to disease.
Harvesting and recycling
Traditionally, potatoes are harvested when the plants take their natural rest. That’s about three months after planting. Early varieties are ready for harvest between June and early July. The herb first turns yellow, then brown and withers. If there are signs of infestation by late blight, the potatoes must be removed from the soil before the fungus spreads to the tubers. Wait for a sunny, dry day and dig up a perennial to test. If the potato peel is abrasion-resistant and ripe and the tubers detach easily from the shoots of the cabbage, you should not wait any longer. A digging fork is best suited for harvesting, but even with a digging fork, injuries to the tubers cannot always be avoided. Lift the above-ground parts of the plant with the digging fork, pull them out of the soil with the attached tubers and use the potatoes quickly. On the other hand, storable late varieties may only be harvested if they are surrounded by a cork layer.
Instead of digging out all the perennials, you can also carefully uncover the roots, remove the largest tubers and pile the rows back up with soil. So the remaining potatoes continue to grow. This method is particularly worthwhile in small gardens or when cultivating in plant bags. Harvested tubers are best kept in a dark, cool and frost-free cellar – depending on the variety, they remain edible until next spring. Sort out damaged, too small or stained specimens immediately. Healthy tubers are left to dry on the bed. The potatoes should dry within a day to such an extent that the still adhering soil almost crumbles off by itself.
Whether harvested by yourself or bought: During storage, make sure that only tubers that are externally flawless without discoloration or conspicuous sunken areas are stored. Visibly diseased tubers should be sorted out consistently. So that the potatoes do not form green areas with harmful solanine, the tubers should be kept as dark as possible. The optimum storage temperature is between four and six degrees Celsius. A warmer storage accelerates the degradation of vitamin C and promotes the formation of germs. At temperatures below zero degrees Celsius, the starch contained converts into sugar and the taste becomes unpleasantly sweet. Even under optimal conditions, tubers can rot time and again. Tip: Several crates instead of a high potato rack facilitate control. Airy crates are well suited for use in cellars or storerooms. Storage in plastic containers or in sealed containers, on the other hand, promotes mold growth. Covering the tubers in storage with newspaper helps to prevent shrinkage of the potatoes due to loss of moisture.
Potatoes are distinguished by their variety like hardly any other crop. Estimates assume more than 2000 varieties worldwide. Whether yellow, brown, pink or blue skin colours with white, yellow or red-violet meat – there is something for every taste. Not to forget are the different growth heights, flower colours and the important meat consistency, which ranges from mealy to solid. On the other hand, there are only a few on the market, since only those seeds are marketed that are on the Bundessortenliste. Approximately 120 potato varieties are permitted in the United States – including the well-known medium-early varieties ‘Agria’ (floury cooking) and ‘Nicola’ (firm cooking) or ‘Sieglinde’, an early, firm cooking variety with smooth, yellow skin and yellow meat. It is the oldest breeding variety in the German List of Varieties and has been approved since 1954. A lover’s variety is Highland Burgundy Red. The late variety has a strong marbled pink meat, which is well suited for puree.
Old potato varieties usually have a fine taste: ‘Rosa Tannenzapfen’ is one of the oldest varieties and produces 30 to 35 tubers per seed potato. Blue Swede’ delivers a safe yield, has a pretty flower and blue overflowing leaves. Among the early potatoes, ‘Rosara’ yields a lot and has a good potato aroma. The earliest tubers include ‘Annabelle’, ‘Christa’ and the red-skinned ‘Rosara’. Sarpo Mira’, a healthy new breed from Hungary, has shown itself to be resistant to the dreaded late blight, and slender tubers are also known as mouse potatoes.
Diseases and pests
The main problem in the cultivation of potatoes is late blight. When the plant is infested, the herb turns brown from mid-June and a silver-white fungus appears on the underside of the leaves, causing the plant to die. As a precaution, do not plant too densely and do not grow next to tomatoes. In case of infestation, you should remove the herb and dispose of it in organic waste or incinerate it. If the plants remain small and the leaves wither, this can be a sign of nematodes. As a preventive measure, it is necessary to observe a cultivation break of three to four years and not to plant any other nightshade plants during this period. Aphids transmit viroses that weaken the plant to such an extent that it yields less each year. One recognizes an infestation by yellowed and rolled up leaves. Field-resistant varieties can handle it. It has also proved successful to mulch the plants with chopped straw in order to contain aphid infestation.
Another pest is the potato beetle. It feeds on the plants and lays orange eggs on the underside of the leaves. The larvae cause further feeding damage. If you recognize and collect the potato beetle at an early stage, you will get the problem with the pest under control. In addition, there are special preparations that can be used for short periods of time and have also proven themselves in organic cultivation.