How To Use Fertilizer When Planting Potatoes (7 Steps)

Potatoes are the perfect garden crop as they can easily be grown in a garden bed or buckets. These awesome tubers make a fantastic addition to any garden, and their yield can significantly increase with the use of fertilizer. So it’s essential to know precisely how to apply fertilizer when planting them for the best results. 

7 steps for easily fertilizing your potatoes: 

  1. Select your potato fertilizer. 
  2. Test your soil’s nutrient content. 
  3. Know your potato fertilizing seasons. 
  4. Apply your potato fertilizer as the package directs. 
  5. Water the fertilizer into the soil. 
  6. Know when to add more fertilizer. 
  7. Monitor your plants for healthy growth. 

In the rest of this article, I will go over the steps for adequately fertilizing your potato crops and a few frequently asked questions about fertilizing these tubers. So, if you want to learn more about the photo’s fertilization process, read on. 

1. Select Your Potato Fertilizer

First, you will need to select a potato fertilizer. Potatoes greatly benefit from fertilizers that are low in nitrogen. This is because nitrogen promotes top growth of leaves, and potatoes grow beneath the ground. So you will need a fertilizer higher in potassium and phosphorus to accomplish more pronounced root growth. 

If you are looking for an excellent potato fertilizer, it’s always a good idea to find a fertilizer formulated explicitly for potatoes. Otherwise, you might end up with a fertilizer that is too high in nitrogen resulting in explosive top growth and very little tuber growth. 

However, it’s important to note that there are other plants that enjoy similar fertilizers as potatoes. For example, tomatoes also grow well with low nitrogen soil, though they will still need some to promote proper leaf growth.

2. Test Your Soil’s Nutrient Content

Next, you should ALWAYS test the soil before adding fertilizer. Soil testing is the only way to ensure exactly what nutrients are in your soil.

Having an accurate accounting of present nutrients is important because too much fertilizer can burn your plant’s roots and stop them from absorbing water and nutrients from the soil. Severe fertilizer burns will result in the death of the plant. 

If you don’t already own a soil test kit, I recommend Luster Leaf’s 1602 Soil Test Kit (available on This kit is great because it will deliver rapid results, and it comes with over 20 tests so that you can check your soil’s nutrients as frequently as you need. 

3. Know Your Potato Fertilizing Seasons

Another critical step is to know during what season you should fertilize your potatoes. Each type of potato will have slightly different fertilization needs and time frames, so it’s essential to do your research before applying fertilizer. 

Common potato types and their fertilization needs:

Potato Planting Seasons Potato Varieties Days It Takes To Grow 
Early Season Yukon Gold, Irish Cobbler, Norland, Caribe. 75-90 Days
Mid Season Catalina, Gold Rush, Red Pontiac, Yukon Gem, Viking. 95-110 Days
Late Season Butte, Canela Russet, Russet Norkotah, Fingerling Salad. 125-130 Days

So depending on the type of potato you are growing, you will want to fertilize during the corresponding season. Be sure to do a little research before planting and applying fertilizer. It’s also important to note that you must fertilize potatoes multiple times per growing season to produce the biggest potato yield. 

4. Apply Your Potato Fertilizer As the Package Directs

Once you have successfully tested your soil nutrient levels, selected a potato fertilizer, and know what season to apply the fertilizer, it’s time to apply it to your garden. When applying fertilizer, it’s best to follow the package’s instructions. 

This is because each brand will have a different concentration of nutrients and a distribution method. If you simply follow the advice that isn’t formulated for your brand of fertilizer, you may end up applying too much and harming your plants.  

Generally, potato fertilizer comes in granules, making it easy to disperse it with a broadcaster. It’s also important to note that potato fertilizer isn’t harmful to other plants, and if you get some in your other flower beds, some of your plants might even enjoy it.

5. Water the Fertilizer Into the Soil

After applying the potato fertilizer as directed, it’s time to release the nutrients trapped in the fertilizer using water. Most fertilizers remain dormant until activated by water. This is because water breaks down the granules of fertilizer, and the fertilizer is pushed by the water deeper into the soil, where the plant’s roots can more readily absorb it. 

To unlock the nutrients contained in fertilizer, simply take a hose and moisten the soil where the fertilizer has been applied. Be careful not to flood the soil as this will leach away essential nutrients from the soil instead of delivering them to the root system. 

If the water starts to pool on the soil’s surface, it’s time to stop watering. You should then allow the soil to dry out before watering again. To promote the best health and not deplete your fertilizer too quickly, it’s best to create a watering schedule for your potato plants. 

6. Know When To Add More Fertilizer 

Next, knowing when to add fertilizer to your potato plants is vital. Granted, potatoes don’t need fertilizer to grow. However, a good fertilizer can increase how many potatoes your plants will produce and what size they will be. If you don’t want a shrimpy yield, you should be ready to fertilize your plants multiple times per season. 

Adding more fertilizer to the soil won’t hurt your plants, provided the soil they are in isn’t already heavily fertilized. This is why it’s best to test your soil prior to fertilization. If you notice signs of over-fertilization, it’s crucial to act quickly by using water to leach extra fertilizer from the soil. 

Depending on your specific brand of fertilizer’s instructions, you will generally want to fertilize the plants every 4-6 weeks until about 2 weeks before they are ready for harvest. But, again, be sure to test the soil before adding more fertilizer and research the type of potato you are growing. 

This will ensure that your plants don’t become over-fertilized and begin to burn from increased salt content in the soil. 

7. Monitor Plants for Healthy Growth

Finally, once you have applied your fertilizer, your plants are set to grow until the next application. Between fertilization, it’s a good idea to monitor your plant’s health and watch for signs of both under and over-fertilization. 

Signs your potato plant is under fertilized:

  • Paling leaves
  • Little plant growth
  • Discoloration
  • Odd spots on leaves

Sadly, it can be tricky to tell if your potatoes need more fertilizer until after you have dug them up. If your potato plant lacks nutrients, you will likely get small, oddly shaped potatoes instead of large healthy ones. 

Signs your potato plant has been over-fertilized:

  • Wilting leaves
  • Discoloration in stems and leaves
  • Yellowing
  • Browning leaf tips
  • Stunted growth
  • White crust on the soil around the plant

If you notice any of these signs, it’s vital that you act to remedy the situation immediately, as fertilization burn can quickly kill plants. 

Frequently Asked Questions 

Do Potatoes Need Fertilizer?

Potatoes need fertilizer because they heavily deplete nutrients in the soil, such as phosphorus and potassium. Potatoes also don’t produce well with high nitrogen soil, resulting in more top growth than tuber growth. Therefore, you should fertilize potatoes 4-6 times as they grow. 

Do You Fertilize Potatoes When Planting?

You do not fertilize potatoes when planting. Instead, you should fertilize them 2 weeks after they have had time to establish themselves. After which, it’s a good idea to apply a fertilizer low in nitrogen or formulated explicitly for potato growth. 

What Is the Best Fertilizer for Planting Potatoes?

The best fertilizer for planting potatoes is any fertilizer with a low nitrogen content and high levels of potassium and phosphorus. This is because nitrogen promotes plant growth; potatoes grow underground, so they need less of that nutrient.

Final Thoughts 

Applying fertilizer to potato plants is straightforward as long as you follow the fertilizer bag’s instructions, test the soil, and reapply as needed. Potatoes quickly deplete nutrients from the soil, so it’s a good idea to observe them and keep them fertilized every 4-6 weeks.

You can read my other article on how to fertilize indoor and outdoor plants here: How to Fertilize Indoor & Outdoor Plants (Ultimate Guide)

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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