How to Add Potassium to Tomato Plants

How to Add Potassium to Tomato Plants

Potassium is the main nutrient when planting tomatoes since it’s key for the maturity of tomato fruits. Therefore, it’s necessary to maintain a high level of potassium in the garden. However, if applied wrongly, potassium uptake restricts the soil’s uptake of, for example, sodium and nitrogen.

Here’s how to add potassium to tomato plants.

Chop a few pieces of potassium-rich banana peels and bury them in your tomato garden. We add potassium to tomato plants since it maintains water status and ionic balance in the soil. Also, add potassium fertilizers or organic fish emulsions to fix potassium deficiency in your tomato garden.

This article gives you a step-by-step guide on how to add potassium to tomato plants safely and efficiently. So keep reading.

Also Check: How To Use Tomato Tone

How to Add Potassium to Tomato Plants

You can add potassium to tomato plants by burying chopped banana peelings in your garden. Banana peels are an organic source of potassium and are very efficient, especially when your budget is low.

Also, banana peels release potassium into the soil slowly once you bury them, allowing constant growth of tomatoes within the stages. To add banana peels to your tomato garden;

  1. Make a collection of banana peels depending on the size of your garden.
  2. Chop them into small pieces, about 2-3 cm long.
  3. Up to a depth of approximately 2-3 inches, bury your chopped banana peels in the tomato garden. The deeper you deposit your peels, the more flowers it’ll produce.
  4. While your tomato plants grow, you can continue depositing other banana peels in an enclosed container. That ensures a constant supply of banana peelings when the plants need them.

Other than being cheap, banana peelings;

  • Are easy to apply in your tomato garden
  • Don’t pollute the environment
  • Require less experience to apply more than other manufactured fertilizers

Why Add Potassium to Tomato Plants?

Potassium is involved in many activities in the tomato plant, including enzyme activation and transporting sugars. Also, potassium aids in ionic balance, pigments synthesis, and maintaining the water status.

High potassium levels in the soil also increase the tomato yields in the garden. We observed in each tonne of tomatoes harvested, plants took in about 5.2-7.2 lb of potassium.

Moreover, an even distribution of potassium in your garden ensures that your tomato fruits age and ripen faster because it activates fruit ripening enzymes. Potassium also increases tomato fruits’ quality by regulating their sugar.

What’s more? An adequate supply of potassium in the tomato plants reduces the chances of your tomatoes getting coloration defects such as yellow shoulder and white tissue. That’s because potassium allows the fruits to ripen faster, reducing the chances of the fruits contracting the disease.

Potassium application in tomato gardens also increases the acidity of the tomatoes and tomato juice. That makes the tomatoes rampant in the market as they attract more customers.

Not to mention, potassium is also essential in all the seasons of tomato growth. Why? It promotes both early and late tomato plant growth, thereby aiding in leaf tissue growth, flowering, and fruit development.

How Do You Fix Potassium Deficiency in Tomato Plants

To fix potassium deficiency in tomato plants, use potassium fertilizers, also known as potash fertilizers. Potash fertilizers have inorganic substances that are rich in potassium. These substances include potassium chloride, nitrate, monopotassium phosphate, and potassium sulfate.

You know that your soil has a potassium deficiency when the leaves and flowers in your tomato garden start changing color. For example, when flowers turn brown, be fast to test the potassium level in your soil to correct its deficiency.

You can combine potassium-rich fertilizers with other water-soluble fertilizers such as nitrate fertilizers for both short-term and long-term fertility.

Additionally, you can fix potassium deficiency in your tomato garden by using Nitrogen Phosphorus Potassium (NPK) fertilizers. NPK fertilizers are a balanced combination of the plants’ key nutrients.

Other than preventing potassium deficiency, NPK fertilizers also ensure that other nutrients such as nitrogen are present. Consequently, your tomato plants get all-around growth across all seasons.

When to Add Potassium to Your Tomato Garden

You add potassium to your tomato garden when you notice that they’re developing flowers. Resultantly, your tomato plants produce flowers and develop fruits faster.

The potassium addition should also be accompanied by a constant supply of nitrogen. Nitrogen helps increase the number of tomato flowers and promotes the growth and development of leaves. However, too much nitrogen is harmful since it favors too many leaves that may overdo the flowers.

At this growth stage, your plants get the strength to bear the weight of the developing fruits. So, the potassium levels you input should be double the nitrogen level in the soil.

You can also add potassium if you notice any signs of its deficiency, for example, brown leaf edges and yellow leaves. Due to the deficiency, the old leaves start losing color. The new ones follow.  Also, fruits near the bottom of the tomato plants ripen unevenly with the formation of yellow patches.

It’s necessary, though, to test the nitrogen and potassium levels in the soil before adding any inorganic fertilizers to the soil.

What Is a Good Source of Potassium for Tomato Plants?

Organic fertilizers such as wood ash and granite dust are the best sources of potassium for tomato plants. Also, others, such as banana peelings and compost, are a piece of cake for your tomatoes.

We recommend organic sources of potassium in your garden since they transfer fewer toxins into the soil. Although they take longer to decompose, they release potassium constantly, favoring tomato growth for a longer time.

Another key source of potassium in your tomato garden is fish emulsion. It favors tomato growth both during transplanting and the flowering season. Besides potassium, it has other essential nutrients such as calcium and nitrogen that aid in root and fruit development.

You can make fish emulsion by blending some fish parts such as bones. To use a fish emulsion, dilute it in a knapsack sprayer and spray it around your garden. For a commercial one, ensure you follow the instructions on the container.

How Do I Add Potassium to My Tomatoes?

To add potassium fertilizer when planting tomatoes, mix the potassium fertilizer with the soil at the bottom of the hole. Then, put some unfertilized soil on top of the fertilized soil before planting the tomato seedlings.

You ensure that the plant roots don’t get into direct contact with the fertilized soil. Otherwise, the fertilizer may scorch the tomato plant.

The next point to add potassium fertilizer is when the plants are flowering. When fertilizing at this point, ensure that you water the tomato plants well. If you fail to water them correctly when adding fertilizers, you’ll put too many potassium fertilizers that burn the plants.

After adding water, scatter your fertilizer on the garden, leaving a space of about 15 cm (6 inches) from the plant base. That space is essential to prevent the fertilizer from getting too close to the plant. If so, the fertilizer can run on the stem and burn the plant.

What Is the Fastest Way to Add Potassium to the Soil?

The fastest way to add potassium fertilizer to the soil is by using commercial potassium fertilizers. A good example of efficient potassium fertilizer is Greensand. Greensand is a green fertilizer obtained from the sea bed where potassium levels are high due to dead fish and other sea creatures.

Prepare your garden by plowing and raking up your soil. Once you buy your preferred commercial fertilizer, spread it over the raked ground as illustrated on the packet.

Generally, add twenty pounds of potash to every 100sq feet of the garden where potassium is ‘very’ deficient. Yet, for other gardens with average potassium levels, add 5-10 pounds of potash.

When applying potassium fertilizers in your garden, ensure no rain forecast in the next 24 hours. That prevents your potash from being washed away from the garden before it’s leached into the soil.

If the soil lacks other nutrients as well, you can use an NPK fertilizer. That kills two birds with the same stone.


Do Tomato Plants Need Extra Potassium?

Yes, tomatoes need potassium more than any other mineral nutrients. Without it, the tomato plant can’t mature and produce the required volume of fruits. When you add potassium to your plants, it helps in: 

  • Formation of stomata
  • Facilitation of transportation of sugars
  • Enhancement of colouration and fruits taste
  • Helping the tomato plant resist infections

Wrapping Up

Potassium is a key nutrient when planting tomatoes since it helps in leaves and fruit development. Therefore, it’s essential to top up your potassium levels in the garden, especially when the tomato plants are flowering.

You can increase potassium levels in the soil by adding banana leaves compost, fish emulsion, or other commercial fertilizers to your garden. Then, follow the guidelines illustrated above on how to add potassium to tomato plants safely and effectively.

We hope this article guides you on how and when to add potassium to tomato plants. Try it and share your experience with us.