Today we talk about the sowing and cultivation of potatoes, a staple vegetable in our diet. Planting organic potatoes in the family garden is not only possible but can also be very rewarding. This is especially true regarding the quality of the product, which, when grown independently, can be much more controlled.
To ensure healthy and thriving potatoes, they require specific techniques and care, which we will try to explain here.
In this article, we will first understand the most suitable soils, the right period and methods for sowing the tuber, and the necessary irrigation type. We will also take a look at the necessary cultivation practices, without forgetting the biological defense against pests. But let’s start from the beginning and learn more about the plant.
Origin and spread of the potato
The potato is native to South America and comes from countries like Peru, Chile, and Bolivia. After Christopher Columbus’ expeditions, it started spreading in the old continent. First in Spain, then in Ireland and England, and eventually in Italy, where it began to be cultivated around 1600. Its widespread use in human nutrition started in the second half of the 1700s. Potato cultivation in Europe became prominent in the northern countries, where it found very favorable pedoclimatic conditions.
In Italy, more intensive cultivation began in the Alpine regions and the northern Apennines. It later spread rapidly to the Central and Southern regions. The cultivation of potatoes on the Calabrian Sila plateau is also well known.
The potato plant
Leaves and flowers
Potato cultivation
The potato, Solanum tuberosum, is an annual herbaceous crop belonging to the Solanaceae family.
This same botanical family also includes tomatoes and eggplants.
The plant has a tufted appearance, with square, hairy stems in green, greenish-red, and sometimes reddish-brown colors.
The leaves are alternate, pinnately compound, consisting of 5 to 9 leaflets. They vary in size and color, ranging from light green to dark green.
The flowers are hermaphroditic and can be white, pink, or violet. They are clustered in terminal or axillary corymbs.
Roots
The roots of the potato plant are fibrous, shallow, and have numerous capillary branches. From the stem, stolons originate, and they thicken at the apex, giving rise to the tuber, which is the potato itself. Depending on the variety and environmental conditions, the plant can produce a smaller or larger number of stolons and, consequently, tubers.
Fruit
The fruit is a berry with 150-300 seeds. Potatoes from the same cultivation can differ in size, shape, and number. Varieties also differ in the color of the flesh and the characteristics of the outer tuberous tissue, i.e., the skin.
Potato cultivation
Tuber characteristics and reproduction
Potato buds or eyes
Potatoes are usually reproduced vegetatively, using seed tubers for planting.
The tuber has buds, also known as “eyes,” arranged in a spiral pattern.
These buds give rise to new plants.
The number of buds increases from the basal part (also called the umbilical part, as the stolon originates from there) to the apical part, known as the crown.
However, not all buds present in the tuber can develop into a shoot.
The Biological Cycle of Potato Cultivation
Potato sprouts ready for planting
The biological cycle of potato cultivation, starting from the tuber, lasts, depending on the variety, from 3 to 5 months. When starting from seeds, this period extends to 5 to 6 months. This is another reason why tuber reproduction is preferred.
The seed tuber, after being harvested at full maturity, naturally undergoes a period of dormancy of about 2 months. After this period, and with temperatures above 6-8 degrees Celsius, the dormant buds sprout, and young plants emerge.
This holds true for seed potatoes or organic potatoes. Unfortunately, the potatoes usually found in the market undergo anti-sprouting treatments.
Pre-Germination
Pre-germination usually begins before potato planting. This technique conditions the sprouting process of the tuber, which will continue its development once placed in the soil. This allows for early planting, without waiting for optimal weather conditions.
Pre-germination of the tubers should start about 4 weeks before planting. For this purpose, the tubers are placed in specific boxes to be positioned in well-lit rooms with white walls, improving illumination. The room temperature, to promote germination, should be between 8 and 14 degrees Celsius, with high humidity.
This practice encourages the formation of short and robust sprouts, which are preferred over excessively elongated and weak ones.
Emergence, Vegetative Growth, and Flowering
Potato flower
Germination is typically followed by emergence. This phase is quite critical for potato cultivation and must be managed very carefully.
Essentially, the young plant emerges at temperatures around 12-15 degrees Celsius, but it is highly sensitive to returning cold, which is quite common in spring.
Once the potato plant has passed the emergence phase, the above-ground growth begins. The duration of this phase varies depending on the variety, temperature, and soil fertility.
After the growth phase, the next step is flowering.
Tuber Formation
Tuber formation begins just before flowering and can be noticed by the enlargement of stolons and their branches. The potato’s maturation phase can be observed through the gradual yellowing of leaves and stems. Potatoes underground also change color from green to yellowish.
At the end of the growth period, the tuber is covered with a layer of cork cells that protect it and enhance its preservation. These cells form what we commonly refer to as the skin.
The number of tubers a single plant can produce, in addition to the variety, may be influenced by climatic factors. The variability in potato size can also be linked to the chemical-physical characteristics of the soil.
Potatoes are ready for harvest when the plant’s leaves turn yellow, and the stems wither.
Environmental Requirements
Potato cultivation prefers a cold temperate climate, making it well-suited for hilly and mountainous areas.
However, it fears intense cold. The leaves are damaged at temperatures around freezing and can freeze and die at temperatures below 0°C. This is why frequent returns of spring frost are feared.
When temperatures drop below -1°/-3°C, the tuber begins to freeze.
When to Plant Potatoes
Therefore, potato planting should start from the end of February in milder hill areas, and continue until April and May in colder mountain regions. Autumn plantings, for spring harvest, are becoming rarer and limited to the South.
As a tuber and root vegetable, the best moon phase for potato planting is the waning phase.
Regarding proper tuber formation, the optimal temperature is between 16 and 26°C. Temperatures above 35°C can cause issues with sugar accumulation in the fruit, and starch accumulation may also be compromised.
The Soil
Potatoes can adapt quite well to various types of soil. However, the best yields are obtained in sufficiently loose, organic-rich, well-aerated soils with a pH between 5.5 and 7.5. Sandy soils with low humus content and clayey soils that favor water stagnation are less suitable. The type of soil also influences the morphological characteristics of the potatoes. In very cloddy soils, the likelihood of tuber damage during harvest increases.
Potatoes develop smoothly in loose or medium-textured soils, encountering fewer obstacles. Thus, it’s important to prepare the soil with care.
Planting Potatoes and Cutting
Furrows for sowing and cultivating potatoes
Planting potatoes in the field is done by preparing furrows in which the potato is placed. The distances between potatoes are 25-30 cm from one another. Then, the furrow is closed, and the potato is covered with soil, remaining at a depth of about 10 cm.
The distance to maintain between rows should be at least 60 cm.
Buried tubers can have different sizes. There are small seed potatoes, which have few buds and, consequently, few sprouts, resulting in a limited number of developed tubers, but of good size.
Larger seeds, however, have more buds and, therefore, generate a greater number of tubers, but of smaller size. To balance the planting, the larger seeds can be longitudinally cut, keeping only a few buds on each part. This operation, which guarantees material propagation savings, should be done with caution. Cutting can promote virus and rot infections.
If you want to cut the seeds, it is advisable to do so a few days before planting. This way, a suberous layer forms on the cut surface, limiting the occurrence of infections. It is also recommended to disinfect the knives before proceeding.
Irrigation
Potato cultivation has a certain need for water, especially during certain stages of the biological cycle. Water should be scarce immediately after planting, as the tuber is already equipped with the necessary water reserves. In the vegetative growth phase, however, water is necessary. Therefore, if the season is dry and there is little rainfall, irrigation should be provided.
Usually, irrigation is done through furrows, taking advantage of the groove, or through overhead sprinklers for large areas.
Water supply should be uniform, meaning it should not be excessive or insufficient. Waiting for the plant to show signs of water demand or overwatering, causing waterlogging that promotes fungal diseases, should be avoided.
It is always best to irrigate in the evening.
During the final stage of tuber maturation, when the plant begins to dry up, irrigation should be stopped.
Fertilization
In organic farming, the organic fertilization of a potato crop should be carefully considered.
Manure can be used, but it must be well matured and buried during the winter season.
If fertilization is done with fresh manure or with spring distribution just before planting, it does not benefit the crop, but rather promotes diseases of the plant’s underground structure and excessive vegetative growth, without an increase in yields.
Therefore, it is better to avoid late manuring if you cannot act in time.
To improve soil quality, you can bury the result of domestic composting. Even in this case, it is necessary to act well in advance of the planned planting period.
Another technique to fertilize the soil naturally without causing issues is to use a leguminous green manure. This process starts in the autumn.
Furthermore, potatoes require a significant amount of potassium. This can be provided to the soil by adding small amounts of wood ash. However, it’s essential to use it in moderation, as ash tends to increase soil alkalinity. Potatoes avoid alkaline soils, i.e., those with a high pH, so moderation is key.
Caring for Potato Cultivation
The main cultural care to be carried out in a potato crop is hilling, an operation with dual purposes.
We have already learned about this technique when discussing fennel and cauliflower. Essentially, a mound of soil is brought back to the base of the plant. This greater mass of soil encourages tuber formation and, at the same time, eliminates weeds.
Biological Defense of Potato Cultivation against Pests and Diseases
Colorado potato beetle
As with other Solanaceae plants, potato cultivation can be affected by various pests. This topic deserves specific treatment, which we will address in future articles. For now, we will cover the two main issues that affect this crop.
Regarding pests, the most known and feared ones are the Colorado potato beetle and the potato tuber moth.
Against these insects, you can intervene using products allowed in organic farming.
Specifically, for larval stages, you can use Bacillus thuringiensis ssp. Kurstaki (strain EG2424). For adult stages, you can use azadirachtin, which is the active ingredient of neem.
As for cryptogamic diseases, the most feared is potato late blight, caused by Phytophthora infestans. It can attack both the above-ground part of the plant and the tubers.
To combat this fungal disease, you can use copper-based products, applying them with great care. It is essential to always follow the product label instructions and apply treatments based on rainfall frequency and irrigation practices.
Harvesting and Storing Potatoes
Potatoes are harvested when the plant is completely dried in its above-ground part. The exact timing will depend on the chosen variety and the planting season.
For home gardens, harvesting is done manually. To facilitate the operation, it is advisable to choose a time when the soil is temperate, neither too dry nor too wet. To unearth the tubers and minimize mechanical damage, it is better to avoid using a hoe or shovel. Instead, a traditional fork is recommended.
Gently enter the soil and lift it to expose the first tubers, and gradually widen the trench.
The storage of potatoes requires great care. The tubers must be thoroughly cleaned of all soil residues. Then, select the smaller seeds for the next year’s potato cultivation.
Potatoes that were damaged during the harvesting process should be consumed as soon as possible.
The larger and compact tubers are the ones to be stored for consumption. The appropriate storage place should be well-ventilated, dark, with a temperature between 5 and 6 °C. Under these conditions, the tubers will not sprout, and your potatoes will keep for a longer time.
Potato Varieties for Planting
We conclude the article on potato cultivation with a classification of seed potato varieties. These are the varieties available in our country that you can buy and grow in your home garden.
The main classification is based on the color of the outer skin, resulting in yellow-skinned and red-skinned potatoes.
Further classification is based on the color of the inner flesh, which can be white or yellow.
Combining these two parameters, we have the commercial classification: yellow skin with white flesh, yellow skin with yellow flesh, red skin with white flesh, and red skin with yellow flesh.
When choosing the seed potato variety, it is advisable to be guided by your preferences. After all, you are producing for household use and not for sale.
Ideally, you would find organic seed potatoes from local and indigenous varieties. However, we realize that this research is not always easy and practical due to the standardization by seed companies.
Further Reading
- NCBI – “Potatoes, Nutrition and Health” – An article discussing the nutritional aspects and health benefits of potatoes.
- SpringerLink – “Potato Production, Usage, and Nutrition—A Review” – A comprehensive review of potato production, usage, and nutritional value.
- Taylor & Francis Online – “Potato Consumption and Risk of Site-Specific Cancers in Adults” – An article exploring the relationship between potato consumption and the risk of specific cancers.
- Nature – “The reinvention of potato” – A research article on the reinvention of potato, focusing on genetic and cellular aspects.
- PubMed – “Microbiology of potatoes and potato products: a review” – A review of the microbiology of potatoes and potato products.
- Taylor & Francis Online – “Potatoes and Human Health: Critical Reviews in Food Science and Nutrition” – A critical review of potatoes and their impact on human health.
- PLOS – “Molecular and biochemical characterization of a potato” – A study on the molecular and biochemical characterization of a specific potato variety.
- Frontiers – “State of the Art of Genetic Engineering in Potato” – An article discussing the current state of genetic engineering in potato research.
- Springer – “Bibliometric Analysis of Potato Research Publications” – An analysis of potato research publications using bibliometric methods.
- Springer – “The Potato of the Future: Opportunities and Challenges in Sustainable Agriculture” – An article discussing the opportunities and challenges in sustainable agriculture for the future of potato cultivation.
