Fertilizing Potatoes: What’s The Best And When Is The Best Time?

The potato, Solanum tuberosum, is probably one of the best known and most popular nightshade plants. The tubers are considered undemanding, easy to grow and high-yielding, especially if a larger quantity is cultivated. Potatoes are even suitable for beginners who are trying their first attempts at cultivation in their own garden or on the balcony. Particularly important when growing tubers is the right form of fertilizer, which is administered at the appropriate time. Precisely because of their unpretentiousness and rapid growth, the starchy plants rely on a large amount of nutrients that you need to administer.

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Best Time

If you have decided to grow the nightshade family (bot. Solanaceae), there is not only one time, which is selected for fertilizing. The reason for this is that potatoes are heavy feeders that require a lot of energy. Therefore, you must follow the three ‘dates’ below for fertilizer application:

Bed preparation (fall): potatoes grow best if you enrich the bed with nutrients already in the previous year. This provides a good foundation to support the formation of microorganisms, which are key to vital potatoes. The fertilizer remains in the bed throughout the winter, providing effective preparation that allows you to get started right away in the spring.

Re-fertilizing (spring): Re-fertilizing in spring is done directly before planting the potato plants. To do this, however, you must first remove some of the old fertilizer before incorporating fresh. The fresher, the better. Directly after that, the potatoes are planted. That is, the post-fertilization happens between April and May, depending on your chosen variety.

During growth: it is recommended to continue to apply fertilizer to the plants during the growing season to ensure that the plants are adequately supplied. However, you can significantly reduce the amount of fertilizer during this time. Base your fertilizing on the vitality of the potato plants. That is, if they weaken, sprinkle some of the fertilizer, preferably directly on the soil. That’s all that’s needed.
As long as you follow these times, you can enjoy a bountiful potato harvest, whether they are early or late potatoes.

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Tip: Especially during the growing season, it is important not to fertilize too much, otherwise there will quickly be an excess of nutrients, which in turn will have a negative impact on crop yields. A little attention is required here.

6 recommended fertilizers to grow potatoes

The best thing about potatoes – you have at your disposal many means that you can use for fertilizing. These include fertilizers for preparation and those that are used during growth. For this reason, it is easy to provide the potatoes with the appropriate nutrients. You can even make some of these yourself. Best of all, these fertilizers can be used for really any potato patch, whether you are planting late or early potatoes:

Horse manure:

Mature horse manure is ideal for fertilizing potatoes. If you can get hold of enough horse manure compost, you can use it for preparation, top dressing and adding nutrients during growth. When doing this, always make sure to use horse manure in a well-stored condition. Fresh manure cannot really be used effectively because it would take too long to release the microorganisms to the soil. Only for preparation would be okay, as the manure can mature until spring. Manure from other animals is not as good.

Horn shavings:

horn shavings are another type of fertilizer that you can easily use for fertilization during growth. Potatoes love the high nitrogen content that the shavings allow, so you should not hesitate and use them. Just add them directly to the soil and gently work them in. Within a short time the nutrients will be released to the soil and thus the tubers.

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With compost you have another means that you can use for fertilization in the previous year. Well-matured compost containing animal waste is particularly good and is incorporated in the same way as horse manure. Since compost is easy to make yourself, you can save a lot of money that you would otherwise have to spend on other nutrient additions such as algae fertilizer or horse manure.

Nettle liquid manure:

Nettle liquid manure is an ideal liquid fertilizer that you can use for the growing season. The advantage about the liquid manure is its easy availability, because you only need a little time, water and the nettles. With the liquid manure you offer your potatoes an intense energy boost that increases yields. At the same time, it acts against pests and improves the soil.

Algae fertilizer:

liquid algae fertilizer is excellent for fertilizing over the growing season, as it acts as an energy booster. Be sure to follow the manufacturer’s directions for application, as this will prevent you from overfertilizing. However, the timing of the application does not change.

Green manure:

With basic fertilizer you prepare the soil in the spring.

The following plants are particularly suitable for this purpose:

  1. Lupines (bot. Lupinus)
  2. Clover (bot. Trifolium)
  3. Garden beans (bot. Phaseolus vulgaris)
  4. Peas (bot. Pisum sativum)
  5. Vetches (bot. Vicia)
  6. These are crushed and simply added to the soil. This is especially recommended if your beds are heavily compacted.

Tip: Alternatively, you could use glauconite for fertilization, which is known in the USA as so-called “greensand”. This natural fertilizer has sufficient potassium, magnesium and iron and can be easily worked into the soil.

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Frequently asked questions

Is it necessary to rotate crops after the potato harvest?

Yes, since potatoes are highly nutritious, a crop rotation must be carried out at regular intervals so that the depleted soil can recover. Therefore, change the location every three to four years and provide the previous one with green manure to enrich it again with sufficient nutrients.

Where can manure be purchased for fertilizing?

Not every gardener has access to horses, cows or other livestock to get enough manure for fertilizing. You can either contact farmers nearby for this, use special internet stores or look in the local classifieds, as manure is often given away or offered at low prices here.

Can synthetic fertilizers be used?

Synthetic potato fertilizers are also possible, but they have a strong effect on the taste and vitality of the potatoes. It makes them more susceptible to disease, harder to store, less tasty, and can quickly overfertilize if you’re not careful.


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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