What’s the Best Potato Fertilizer?

When it comes to fertilizer for potatoes, the term “best” is nearly always subject to interpretation. Your gardening situation, climate, finances and the availability of a particular type of fertilizer all play a part in determining what’s best for your situation. Luckily, there are enough options to meet any need.


Potato Nutrient Needs

Potatoes will do best and produce a larger crop with certain soil conditions and nutrients. First, they prefer an acidic soil, with a pH around 5.0 to 5.5. However, soils with a pH around 6.5 will have more readily available nutrients. When growing in an acidic soil, fertilizer is usually required. Second, potatoes don’t need lots of nitrogen, but they do need phosphorus and especially potassium.

Possible Potato Fertilizers

There are many fertilizers, both commercial and home-made, that are helpful for potatoes. They include:

  • Aged manures
  • Commercial organic fertilizer
  • Manure or seaweed teas
  • Seaweed compost or granules
  • Mixtures of compost, bone meal, wood ashes and kelp or other seaweed products
  • Compost
  • Mulches of straw, hay, leaves or grass.

Commercial Fertilizers

Commercial fertilizers are available as powders, granules, in liquid form and in timed release preparations. One advantage of these is that you know exactly what the NPK ratio is. They are easy to store and apply. However, they can be expensive, especially in a large garden. One downside is that commercial fertilizers do not supply humus, which is very important for the loose, friable soil potatoes prefer.

Making Your Own

What are often called natural fertilizers are substances that break down more slowly than commercial fertilizers. Remember to keep proportions correct: two parts nitrogen, one part phosphorus and three parts potassium. You can make your own by using:

  • For nitrogen – alfalfa or cottonseed meal, fish emulsion
  • For phosphorus – bone meal and rock phosphate
  • For potassium – kelp meal or granite meal.

Liquid Fertilizers

You can choose from commercial liquid fertilizers or make your own from compost or manure. One advantage of these fertilizers is that they can be applied in dilute concentrations and more frequently. This means a steady supply of nutrients with less risk of burning plants. In areas where water is in short supply, you can fertilize and water in one application.


Compost may be the ideal fertilizer for almost any food crop. If made well, it is rich in nutrients. It has plenty of humus and is easily applied by simply tilling it into the soil or spreading it on top. It must be properly stored and protected from the elements to prevent leaching of nutrients. No matter what the size of your garden, you can make some compost.

Text: Garden.eco