Potato Fertilizer: How To Fertilize Potato Plants Correctly

High-yield cultivation of tasty potatoes in harmony with nature is one of the greatest challenges in home gardening. Balanced nutrient supply plays a key role in the cultivation program. Since it is taboo to use industrial fertilizers in an organically managed kitchen garden, the focus is on organic potato fertilizers. This guide lists the best natural fertilizers and gives tips for the perfect dosage and the ideal timing. Here’s how to fertilize your potato plants properly.

Fertilization should starts in autumn

When using organic potato fertilizers, chemical ingredients are left out. To ensure that your potato plants benefit from the natural nutrients, busy soil organisms are needed in advance. Earthworms and microorganisms process organic fertilizer in such a way that it can be absorbed by the roots and is thus available to the plants. In addition, dormant nutrient stocks in the soil are activated so that they can also be used to naturally promote growth. This process requires a time frame of several weeks in summer and several months in winter. As a result, ready-to-use compost and other natural fertilizers will strengthen your potato plants for a much longer period of time than short-term artificial fertilizers.

This short excursion into the basics of natural nutrient supply makes it clear that ideally you should already be active in the potato bed in the fall of the previous year. By taking one of the following preparatory measures or a combination of them, you provide your potato plants with the best starting conditions.

Horse manure

  • Dig the bed 2 spades deep in the fall.
  • Remove stones, root debris, weeds and thick clods of soil
  • Incorporate composted horse manure or stable manure that is at least 18-24 months old.
  • Burrow the organic material about 1 spade-deep at a rate of 3 to 5 liters per square meter

Fresh manure of any kind is not suitable as potato fertilizer. Only after hot rotting, a cool build-up phase and humus conversion by industrious compost worms will fresh manure and dung meet the expectations of a good natural fertilizer for your potato bed.


Where horse manure or stable manure is not available, mature compost takes over as a preparatory nutrient supply in the fall. Apply the organic material to turned, cleaned soil at a rate of 5 liters per square meter. Please do not rake compost as deep as manure or dung. Potato fertilizer should be available where the majority of soil organisms reside. When measuring the amount, keep in mind that in the prepared potato bed in the spring strong-hungry plants enter

Green manure

As an alternative or in combination with manure and compost, we recommend sowing green manure on the soil surface in the planned potato bed. Winter-hardy seed mixtures, such as Landsberger Gemenge or Terra-Life Solanum, leave a loose, well-aerated soil rich in oxygen and nitrogen in spring. In addition, green manures suppress troublesome weeds. Here’s how to do it right:

  • Rake the bed area and smooth it repeatedly with a rake.
  • Spread the seed of the green manure on it in large cubes.
  • Rake the seeds into the surface and press them down with the help of a lawn roller.
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Finally, water the seed with a fine spray and mark the bed so that it will not be walked on. Care during the winter is limited to watering in dry conditions when neither snow nor rain will provide the necessary moisture. Before planting time begins for your potatoes, mow or scythe down the green manure and work the plant residue into the clod.

Tip: Garden practice has proven that consistent fertilizing with compost keeps the dreaded Colorado potato beetle at bay. Moreover, smart mixed cropping effectively prevents the ravages of late blight by sowing marigolds, spinach, parsley or nasturtium in the potato bed.

Planting and fertilizing go hand in hand


When seed potatoes get into the ground, they meet – thanks to the soil preparation in the previous year – an active soil life with a wide range of nutrients. To keep it that way during the long cultivation period until the autumn harvest time, refresh the natural fertilizer now. Early fertilization is especially important in potato cultivation, because nitrogen requirements are at their highest before the row closure in the bed and drop significantly until flowering time. Here’s how to get the fertilization program started at planting time:

  • Work in mature compost before planting potatoes in the bed.
  • A dosage of 2 to 3 liters per square meter is ideal
  • In addition, sprinkle a few handfuls of horn shavings or horn meal over the compost

By mixing compost and horn shavings, both natural fertilizers promote each other’s effectiveness, benefiting the germination and growth of your potato plants. Therefore, place the seed potatoes on the recommended nutrient bed with a 5 cm soil cover and then water on.

Nutrient supply ends with flowering

Following the initial fertilization at planting time in April/May, potato plants need regular fertilizer until the end of the flowering period. If you favor compost as a potato fertilizer, administer about three liters of the material every two weeks
per square meter. To ensure that the nutrients are absorbed quickly, water abundantly after each fertilization. Continuing to apply nutrients after flowering is a waste of valuable resources. Further additions of nitrogen will only force the growth of the leaves, which will ultimately be at the expense of the coveted tubers.

Tip: When young potato plants have reached a growth height of 15 cm, they are regularly mounded. For this purpose, the raked, fine-crumb soil is pulled up to the shoots. The reward for the little effort is a higher yield, better taste and longer shelf life for storage potatoes.

Alternatives to compost as a potato fertilizer.

Home-made compost is considered a premium fertilizer for potato plants. Unless there is an opportunity in the garden for managing their own compost pile, home gardeners turn to the following potato fertilizers as an alternative. These options are available for organic nutrient supply:

Fertilizing potatoes with plant liquid manure

Plant liquid manure contains the concentrated power of nature to supply ornamental and agricultural plants with all important nutrients. Nettle liquid manure in particular makes an excellent organic potato fertilizer thanks to its high nitrogen content. Supplemented with potassium-rich comfrey liquid manure, a valuable natural fertilizer is created, which is quickly available to potato plants thanks to its liquid form. Production and administration are as simple as can be. How it works:

  • Fill a wooden tub with 10 liters of rainwater.
  • Place 500 grams each of fresh nettle and comfrey leaves in a coarse-meshed bag.
  • Put the bag in the water and cover the tub with wire mesh.
  • Stir daily until fermentation is complete.
  • Stir in primary rock flour, bentonite, chamomile or valerian leaves to reduce odor
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The fermented, sieved plant slurry is diluted with water in a ratio of 1 : 10. Until the end of the flowering period, sprinkle the soil once a week in the early morning or in the evening hours. By mulching at the same time with comfrey and nettle leaves, the effectiveness of the organic fertilizer is enhanced.

Sheep’s wool – innovative supplement for compost & co.

The knowledge of sheep’s wool as a rich, organic fertilizer was long lost and has recently been rediscovered. Unwashed sheep wool contains important main nutrients, such as nitrogen, potassium, phosphorus or sulfur. When the material enters the soil, it loosens the topsoil and regulates the pH. Thanks to a high water retention, sheep wool absorbs 3 times its own weight in moisture to successively release it to the surrounding plant roots.

Administered once, sheep wool supports the growth of potato plants throughout the entire cultivation period. Ideally, combine this innovative fertilizer with compost, horn shavings or plant soaks, as it is not sufficient as a sole fertilizer for heavy growers. You can buy sheep’s wool in its original form in specialized stores. It is easier to administer the fertilizer as pellets, which are placed 5 cm deep in the soil and doused with water.

Recommended potato fertilizer from the store shelf

Kartoffeln richtig düngen

Compost, horn shavings, and plant yeast are very popular as organic potato fertilizers. However, if you do not have access to these fertilizers, specialist retailers have a wide range of ready-to-use alternatives. With the following products, you can fertilize your potato plants in harmony with nature:

Potato fertilizer from Cuxin

The special fertilizer scores with the NPK formulation 5+4+15, whose components are exclusively of natural origin. The high potassium content guarantees a high-yield harvest and contributes to the perfect aroma. The dust-free granules are spread on the ground in a dosage of 80 to 150 grams per square meter and rained in. The content of a 1.5 kg carton is sufficient for an 18 square meter bed or 50 potato plants.

Organic natural compost

For a long time, manufacturers have been fiddling with how to make mature natural compost in the best quality as a finished product can come into the trade. Today, numerous well-known suppliers carry peat-free organic compost in their product range, which is also approved for commercial organic cultivation of potatoes and other vegetables. With more than 90 percent of our peatlands already destroyed as a result of peat cutting, please look specifically for a peat-free product when purchasing.

Organic vegetable fertilizer from Compo

To fertilize your potato plants properly, a good vegetable fertilizer meets the requirements just as well as a special fertilizer. Compo’s organic vegetable fertilizer is conveniently administered as a liquid fertilizer by adding it to the water used for watering. This makes it particularly suitable if you grow potatoes in large tubs.

Naturen organic food for fruits and vegetables

The organic liquid fertilizer is composed exclusively of natural raw materials and is approved for organic cultivation. Thanks to its liquid form, it is equally suitable for beds and balconies.

Organic fertilizer from seaweed by Shropshire Seaweed

An innovative fertilizer that enjoys top ratings among home gardeners is based primarily on seaweed from the Atlantic Ocean. The liquid fertilizer is so powerful in its effect on growth and yield that it is diluted at a ratio of 1 : 500. Not only in the potato bed the natural fertilizer brings the plants in momentum, but also in other vegetable beds and flower beds.

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Dehner Organic Fertilizer for Fruit and Vegetables

The manufacturer has taken the beneficial effects of poultry manure as a potato fertilizer as an opportunity to create a ready-to-use organic fertilizer from it. Poultry manure is rich in nitrogen, from which potato plants benefit until flowering. Thus, this product is the ideal option for home gardeners who do not have immediate access to composted manure for organic nutrient supply to potato plants.

Lime fertilization – a double-edged sword

Potato plants are considered tolerant to soil acidity. A pH value between 4.4 and 7.5 is sufficient for a rich crop yield. Only deflections below or above these values impair growth and productivity. Since the average garden soil is within the broad tolerance limits, lime does not count as a standard fertilizer. If, on the other hand, you are striving to grow potatoes with a full flavor, natural algal lime comes into focus. The more lime-poor and acidic the soil, the more the tubers lose flavor.

A simple pH test from the garden center shows how the soil acidity in the potato bed is doing. Values below 5.5 indicate that you should optimize the organic nutrient supply with algal lime so that the tubers develop their full flavor. Please keep a time distance of 3 to 4 weeks to compost, manure or dung. For each square meter of bed area, administer 150 to 250 grams to raise the pH by one point.

Lime fertilizer in the potato bed, however, is controversial among experts. The fertilizer is suspected of causing or at least promoting the dreaded potato scab. Proponents of lime fertilization argue that there is a lack of convincing evidence for a causal link between potato scab and liming.


After reading this guide, organic nutrient management in potato cultivation is no longer a closed book, even for beginners. If you want to do without chemical fertilizers, prepare the bed in the fall of the previous year with composted manure, horse manure or mature garden compost. Just in time for planting, the seed potatoes will find a natural nutrient buffet in the bed for vigorous growth and a bountiful harvest. In the course of the summer cultivation period, until the end of the flowering period, the used nutrients are regularly refreshed with purely natural potato fertilizer. Those who do not want to or cannot compost themselves can make use of a wide range of products from the specialist trade.


  • 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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