What is the Best Fertilizer to Grow Potatoes?

The best fertilizer to grow potatoes can be organic or inorganic. Either way, it has to be a multi-nutrient fertilizer. Potatoes require fertile, loose and well-drained loamy soil, favorable climate and local environmental conditions, and a proportionate combination of three major nutrients: nitrogen, phosphorus, and potassium.

The best fertilizer to grow potatoes should have less nitrogen than phosphorus and potassium. A fertilizer with 8% nitrogen, 24% phosphorus and 24% potassium is necessary for soils that are not desirably fertile. For fertile soil, an all-purpose granular fertilizer with 5% nitrogen, 10% phosphorus and 10% potassium should suffice. 

Soil Health and Nutrients Requirement

Potato is one of the easiest crops you can cultivate. It grows in rather diverse climatic conditions. However, if you are planning to grow potatoes in your garden or the small farm in your backyard, then it is a tad more complicated than cultivating tomatoes or cucumbers. This has more to do with the fact that potato is a root vegetable, so you cannot see how it is growing and shaping up. All the preparation, planning and execution should be well-informed and appropriate for an optimum yield at the end of the growing cycle.

It is essential to talk about soil health and nutrients requirement before one can precisely answer what is the best fertilizer to grow potatoes. Potatoes need slightly acidic soil. The pH has to be around 5.8 to 6.5. Potatoes do not grow in alkaline soil. They do not grow in saline soil. The soil has to be loamy and must not be rich in clay. The rigidity of clay prevents the expansion of the tubers as they grow underground.

Clay also retains more moisture than loam. Potatoes need sufficient water, but the soil should be well drained. Retention of water or moisture will inhibit the growth of the crop. Potato is also a demanding crop when it comes to nutrients. While all types of crops require nutrients, potatoes need a bit more. This is why soil health is of utmost importance. Else, you would have tiny, funky or mushy and misshaped potatoes, not the kind of yield anyone wishes for.

Ideally, you should know the exact composition of your soil to understand its health or fertility, and hence suitability for growing potatoes. This can be easily done with the help of a soil testing kit. You may also send a sample of the soil, from the precise plantation area, to a nearby laboratory that conducts agricultural tests. A soil test will tell you if you need to reduce the pH to make the ground more acidic for potatoes. The soil test will also tell you if there is any major deficiency of certain nutrients. This deficiency must be addressed with fertilizer, either chemicals or organic materials.

Only when you know for certain what the nutrients requirement is can you choose the best fertilizer to grow potatoes. Still, there are other factors that should be considered.  

Type of Potato and its Growing Cycle

In the United States, there are more than two hundred varieties or types of potatoes. In the North, Central, and South Americas, there are over four thousand varieties of potatoes. These exclude the approximately two hundred varieties of wild potatoes. There are more varieties as you move to Europe and Asia. Potatoes can also be grown in Greenland, so the variety there is certainly not what you would cultivate in India.

The two hundred or so varieties of potatoes in the United States are classified in seven groups. These are russet, red, yellow, white, purple, fingerling and petite. The type of potato you are planning to grow shall determine the nutrients requirement. While most common varieties have nearly identical requirement, yet the growing cycle varies and naturally the approach to fertilization must be conducive.

As and when you test your soil and prepare it for planting, you should consider the type of potato you intend to grow and accordingly understand its growing cycle. This will enable you to not only choose the best fertilizer to grow potatoes, but also ensure that you are fertilizing the soil appropriately and at the right time. Over-fertilization and under-fertilization are both equally futile.

Best Practices of Fertilization to Grow Potatoes

Start working on the soil around ten days to a fortnight prior to planting. You should aerate the soil. Potatoes need loose soil so the tubers can grow and expand. The soil should not be rigid, lumpy and tightly held. Add organic fertilizers to enrich the soil, if it is not fertile enough. The soil test should tell you if pre-planting fertilization is necessary.

Farmers use bone meal, blood meal, seaweed and other organic materials to add nutrients to the soil. This should precede planting if the soil is not sufficiently fertile. If the soil is already rich in nutrients, then these organic fertilizers may be applied after planting the crop, usually a fortnight later.

As and when the soil is ready, plant the potato seeds with the shoots poised firmly upwards. If you live in a region that receives plenty of sunlight and the climate has scorching summers, then you may want to consider some kind of protection for the soil. Sustained exposure to strong sunlight or extreme warm temperatures is not good for tubers. The potatoes will tend to have a greener skin, which tastes bitter. Effectively, you would not have a palatable yield. You can use mulch to cover parts of the soil that do not have the growing shoots.

The frequency of fertilization depends on the type of potato and its growing cycle. Some potatoes grow in twelve weeks. Some require up to twenty two weeks. The general range of the growing cycle is seventy to a hundred and twenty days. There is a generic or standard approach to fertilization for potatoes. You should fertilize the soil two weeks after planting, then you should do so once a month till the last fortnight of the growth cycle. These last two weeks before the harvest do not require any watering, so fertilization is futile.

Fertilization or using even the best fertilizer would be ineffective without a proper watering routine. As mentioned already, potatoes need sufficient water during the five distinctive phases of growth. These five phases are sprout development, vegetative growth, tuber initiation, tuber bulking and maturation. Water is also necessary to enable the fertilizer in a granule form to find its way down into the soil. Spreading or applying the fertilizer on or close around the shoots of the crop would not help. This would cause burn and the foliage would be discolored. Also, the tubers will not get the nutrients, so they would not grow appropriately.

Ideally, the best fertilizer to grow potatoes is one that is rich in compost, or well-rotted manure, and other organic matters such as bone meal, blood meal, seaweed and wood ashes. The chemical fertilizer you use should have less nitrogen and more phosphorus ; potassium. This is primarily due to the nature of the crop.

You don’t need glorious foliage for the shoots of the crop. Nitrogen facilitates better growth and development of foliage. The fertilizer should have more phosphorus and potassium for optimum development of the roots, which is the fundamental requirement for growing tubers like potatoes.


Charlie loves to garden with his family and friends. His favorite vegetables to grow are cucumbers, string beans and lettuce.

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