September 30, 2025, 3:35 pm | Read time: 4 minutes
Few tubers have as many fans as the potato. In the garden, it is a classic that, with proper care, reliably yields crops year after year. With the right soil preparation and fertilization, both the yield and taste of potatoes can be optimized. Read how, when, and with what you should fertilize potatoes in this article.
The Most Important Nutrients for Potatoes
While potatoes are not as nutrient-hungry as other nightshades, they are still considered heavy feeders. For them to grow vigorously and produce many tubers, nutrients must be available in the soil from the start. Nitrogen promotes the growth of green plant parts. Phosphorus and potassium, on the other hand, are important for the formation and ripening of the tubers, with potassium also positively affecting aroma, firmness, and storability. Special potato fertilizers are usually potassium-rich.
Fall Bed Preparation with Manure or Compost
The soil can be prepared for the upcoming potato season as early as fall. This involves deeply loosening the bed and enriching it with organic material. Suitable options include rotted manure or compost, which not only provide nitrogen, phosphorus, and potassium but also other nutrients important for balanced growth. Manure and compost also contribute to humus formation, invigorate the soil, and strengthen the plants from the start.
As a guideline, about three liters of manure per square meter are recommended for potatoes. More compost can be used, as heavy feeders like potatoes can handle five to ten liters per square meter. Both should be worked shallowly into the soil. For manure, the higher the straw content, the greater the amount that can be applied.
Green Manure as Bed Preparation
Green manure is also suitable for preparing the soil for potatoes. Nitrogen-fixing plants like sweet lupine or field beans enrich the soil with nitrogen through their root nodules. Sowing in the summer of the previous year creates the best conditions for the coming season. The plants are mowed in the fall and can remain as mulch on the bed. In spring, the remnants can be worked shallowly into the soil.
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Starter Fertilization in Spring
If the soil was not prepared in the fall, this can be done in the spring before planting the potatoes. Mature compost has proven particularly effective, as it acts evenly and does not overwhelm the young plants. When planting, it is sufficient to add a heaping trowel of compost per tuber into the planting hole or to sprinkle the compost into the planting furrow. Adding horn shavings or clover pellets can provide additional nitrogen for the potatoes.
Note: However, one should not overdo it with nitrogen, as too much of this nutrient leads to increased foliage growth and can promote the development of diseases.
Support During the Growing Season
Targeted nutrient application is also recommended during the growing season. In addition to organic potato-specific fertilizers, homemade plant liquid fertilizers can be used every two to three weeks from the sprouting of the plants until harvest. Nettle and comfrey liquid fertilizers have proven particularly effective. The former primarily provides nitrogen for vigorous growth, while the latter is rich in potassium and supports the tubers.
The liquid fertilizer is diluted with water at a ratio of one to ten and applied in the cooler morning or evening hours. Mulching with nettle or comfrey leaves enhances the effect and simultaneously improves soil moisture.