The 6 Best High Potassium Fertilizers in 2023

Keeping your lawn and garden healthy is important. Not only does it make your property look nicer, but it also helps keep the pests away. One of the most important things for keeping your lawn and garden healthy is using fertilizer. But with so many different types of fertilizer on the market, which one should you choose? 

Fertilizers that are high in potassium are a great option for homeowners, as they provide many benefits to plants. Potassium is an essential nutrient that helps in photosynthesis, water uptake and protein synthesis. Not only that, but potassium also helps improve the plant’s resistance to disease.

If you’re looking for the best high potassium fertilizer to help your garden grow, check out this list of the six best fertilizers in 2023. All of these fertilizers are sure to give your plants the boost they need. So, whether you’re looking to improve your home’s curb appeal or keep your plants healthy and happy, read on for some great recommendations!

What Is Fertilizer?

A fertilizer is any materials that you add to the soil or plant tissue that then give nutrients to the plants. Fertilizers nourish your grass and garden with important minerals in order to produce healthy plants.

Fertilizers have traditionally been composed of mostly organic components such as different types of animal manure, compost, mined minerals, and crop rotations, but synthetic fertilizers have become more widespread in the last few centuries.

How Does It Work?

Fertilizers promote plant growth. They can accomplish this via two methods. The first approach is to provide plants the nutrients they need, and are able to absorb, to develop. Fertilizers are made up mainly of nitrogen, phosphorus, and potassium. Each of these three macronutrients has a distinct function, and will be defined below.

Another function of some fertilizers is to improve the soil’s ability to keep moisture and support its aeration. However, this is not as common, and is less useful compared to the nutrients added.

Types of Fertilizer

There are several different types of fertilizers you will come across when shopping for a high potassium fertilizer, and which type you choose will depend on your specific needs and those of your lawn.

Liquid Spray vs. Granular Fertilizer

Granular fertilizer comes sold as very small granules that you can spread around your lawn. These fertilizers can be spread with a broadcast spreader and then either mixed into the dirt by hand or via top dressing, which is sprinkling the pellets on the root zone of the plant.

Liquid fertilizers, on the other hand, are made up of either dry granules or liquid concentrates that must be dissolved/diluted in water before application. You apply this type of fertilizer by spraying the roots of seedlings, and the leaves and stems of vegetation and plants that have already partially grown.

Organic vs. Inorganic Fertilizer

Any potassium fertilizer you use will either be inorganic or organic. These two types use different ingredients, and the nutrients they have get introduced to the plants in different ways.

Synthetic or commercial fertilizers are produced through chemical synthesis; nevertheless, the vast majority of them do use nutrients that occur naturally in mineral deposits. These fertilizers are highly concentrated, and give the plants exactly what they need and nothing more.

Inorganic or artificial fertilizers primarily use nitrogen, phosphorus, and potassium in high concentrations, and often have very little else.

Examples of organic fertilizers are compost, different animal manures, blood meal, alfalfa, cottonseed, and kelp meal, and bone meal. The nitrogen-phosphorus-potassium levels in these fertilizers are usually lower than inorganic ones, but they also provide the soil vital organic matter, which both enhances water retention and movement and works in tandem with soil-dwelling micro-organisms to better nourish the plants.

Here is a list of our best organic fertilizers for your lawn and garden.

Slow Release vs. Quick Release Fertilizer

Fertilizers are either slow-release or quick-release. These two types of fertilizer work differently, so it is important to know which one will be better suited for your needs.

Slow-release fertilizers release nutrients over time in a slow, drip-feed manner. On the other hand, quick-release fertilizers are meant to deliver nutrients more swiftly, though often in lesser amounts.

Granular fertilizers are more likely to be slow-release and liquid fertilizers more commonly quick-release.

NPK Ratios – Macronutrients

The nitrogen-phosphorus-potassium (N-P-K) ratio is one of the most crucial elements to consider while selecting fertilizer since it determines plant growth. Your objective when selecting a fertilizer should be to find a ratio that is appropriate for your plant’s species type based on its specific demands.

Fertilizers list their NPK components in ratio form, such as 10-10-10 or 4-3-4. The sequence is always Nitrogen (N) first, then Phosphorus (P) and then Potassium (K), so 10-5-8 would mean the fertilizer contains 10% nitrogen, 5% phosphorus, and 8% potassium. For a high potassium fertilizer, you want to buy one that has a higher amount of potassium – for example, 6-3-9 or even 0-0-12 or similar.

In addition to the NPK big three, there are three other common macronutrients – calcium, magnesium, and sulfur – as well as numerous micronutrients including copper, iron, manganese, zinc, and boron.


Nitrogen is used primarily to promote leaf and petal growth in plants and grass, and gives grasses and leafy plants their dark green color.


Phosphorus is a primary nutrient for roots, flowers, seeds, and fruit growth. It’s necessary for plant growth in every stage. It is also called Phosphate.


Potassium helps in the development and growth of plant stems and roots, as well as facilitates water circulation in turf grass and vegetables and aids in flowering and fruiting. It is also seen as Potash.

When To Use Potassium Fertilizer

In addition to the uses mentioned above, potassium provides and helps plants and soil with enzyme and stomata activity, photosynthesis, transport of sugars, water, and nutrients, protein and starch synthesis, and benefits crop quality.

If your soil has a potassium deficiency, there are a few signs you can be on the lookout for. The plants in your garden will have weak stems, and their leaves might be floppy and unable to stand up to their full height. Also look for discoloration of the leaves, they could have yellow or brown tips, or they might have scorch marks along their edges.

If you don’t know exactly what is wrong with your lawn and garden, usually a good idea to test the soil before applying fertilizer to determine its natural fertility and pH levels. The findings will indicate which nutrients your soil may need, so you can apply them in the form of fertilizer.

Natural Sources of Potassium

In addition to the commercial fertilizers you can buy below, there are many naturally-occurring sources of potassium you might find or search for that can be very useful to your potassium-deficient soil.

Organic sources of potassium include wood ash, which is between 3-8% potassium by weight, kelp meal (4-13%), charred cucumber skins (27%), banana peels (5-8%), eggshells (5-8%), comfrey (5%), sawdust (2-4%), and granite dust (3-6%).

Spreading any of these products in your yard and mixing them into the dirt will benefit your soil and plants by providing potassium, as well as nitrogen and phosphorus in some cases. You can find many of them locally, even in your own house or backyard; or you can ask a neighbor or perhaps a local farm or professional gardener that you know.

The Top 6 High Potassium Fertilizers

We have found and listed the best fertilizers that have high amounts of potassium. All of these are highly rated and reviewed, so look through them and choose which one is best for your lawn!

#1. Simple Lawn Solutions High Potassium Lawn Food Liquid Fertilizer

Simple Lawn Solutions - High Potassium Lawn Food Liquid Fertilizer 0-0-25 - Concentrated Spray - Turf Grass Vigor and Plant Hardiness - Summer and Fall - Any Grass Type (32 Ounce)
  • Plant Hardiness: Potassium Promotes Turf Grass Hardiness, Helping Lawns Prepare For Temperature Change and Stressful Conditions. Potassium Deficient Lawns Can be Less Resistant to Stress. Great to use in the Summer and Fall.
  • High Potassium Lawn Food Fertilizer: Treats Potassium Deficiency. Potassium Can Enhance The Plant’s Endurance to Stress if a Deficiency is Present. Potassium is involved in Carbohydrate Formation, Photosynthesis, Enzyme Activation, and the Formation of Proteins. The Application of Potassium will Generally Not Show a Visible Response.
  • Easy to Use: Our 0-0-25 Lawn Fertilizer Food Comes With a Ready-To-Use Hose End Sprayer that Applies the Perfect Ratio of Liquid Nutrients for Lawn Applications. Covers up to 3,200 Square Feet, when Using the Attached Sprayer.
  • Produced In The U.S.A: 0-0-25 is Manufactured in the United States of America, by a Family Owned Business with over 25 Years of Former Experience in the Commercial Professional Turf and Agriculture Industry.
  • Can Be Used On Any Grass type: Saint Augustine Grass, Bahia Grass, Bermuda Grass, Centipede Grass, Kentucky Bluegrass, Annual Ryegrass, Perennial Ryegrass, Tall/Fine Fescues, Zoysia Grass, and more!

The Simple Lawn Solutions High Potassium Lawn Food Liquid Fertilizer is our number one choice for the best highly-concentrated potassium fertilizer. This fertilizer is great for use in the summer and fall seasons, and it is simple as adding a garden hose to the spray bottle and spraying up to 3,200 square feet of lawn.

This Lawn Food Liquid Fertilizer has an NPK ratio of 0 – 0 – 25, so it is highly effective, and it is made from the cleanest and purest sourced ingredients. It also contains sulfur, which aids in the formation and production of essential enzymes and proteins. It can be used on any grass type, including St. Augustine Grass, Zoysia Grass, and Bermuda Grass.

A fertilizer with a high amount of potassium helps to regulate the durability of both turf grasses and garden plants, which means your lawn will be better prepared for changes in temperature and more resistant to stressful conditions such as drought, disease, or heavy rainfall. It also helps to create carbohydrates and proteins within the plants, activate enzymes, and facility photosynthesis, so your plants and grass will be more healthy than ever.

#2. Voluntary Purchasing Group Muriate of Potash

Hi-Yield (32145) Muriate of Potash 0-0-60 (4 lbs.)
  • This Potassium plant supplement helps plants form healthier stems, roots and tubers.
  • Great for tulips, carrots, potatoes, and other rooting subterranean plants.
  • Do not apply this product directly to roots. Mix into soil and water thoroughly.
  • 4 pounds of Muriate of Potash can be used to treat 800 square feet of ground.
  • Apply at a rate of .5 pounds per 100 square feet of soil.

The Voluntary Purchasing Group Muriate of Potash is our second choice for the best fertilizer with a high amount of potassium. This fertilizer is made from muriate of potash, which is just another name for Potassium Chloride. Potassium Chloride is a great fertilizer because the high potassium content is perfect for growing potatoes as well as other root vegetables like carrots and squash that need a large amount of potassium to grow, like carrots and squash.

The Muriate of Potash helps with the formulation of vegetative matter as well as root production. It has an NPK composition of 0 – 0 – 60, meaning it contains 0% Nitrogen and Phosphorus but a huge 60% Potassium mixture. It is highly concentrated, so you can dilute it down and make it last for a long time.

This Potash from the Voluntary Purchasing Group is a high yield formula, so a single four pound bag can cover up to 800 square feet of viable garden soil. The potassium in the fertilizer also helps to produce strong, sturdy stalks on vegetables, colorful and healthy blooms on flowering plants, as well as healthy stems, roots, and tubers in root vegetables.

This potash will get your leaves turning green and growing faster, and helps to establish healthy roots systems even in transplants and newly-planted bulbs. 

#3. Down to Earth Organic Langbeinite Fertilizer Mix

Down to Earth Organic Langbeinite Fertilizer Mix 0-0-22 Granules, 5 lb, Pack of 1
  • Down To Earth Langbeinite 0-0-22 is a naturally mined crystalline mineral that supplies the water-soluble sulfate form of three vital plant nutrients: potassium, magnesium and sulfurs
  • Its maximum chlorine content is less than 3.0 percent, minimizing the potential for fertilizer “burn,” and its neutral pH does not alter soil activity
  • Potassium contributes strongly to overall plant health by regulating internal processes. Since potassium makes up part of the fluid of the plant, it is found throughout plant tissue, meaning plants need a strong source of potassium as they grow
  • Potassium deficiencies lead to weak stalks and immature roots, leaving the plant susceptible to insects
  • Keep it Real, Keep it LightRail; Solidly made in the USA since 1986

The Down to Earth Organic Langbeinite Fertilizer Mix is an all-natural fertilizer from Down to Earth that provides a safe and healthy boost of potassium to your lawn and garden. It contains an NPK ratio of 0 – 0 – 22, so it has lots of potassium for plants that need it, and it contains magnesium, which helps the plants to synthesize chlorophyll, and sulfur, which is necessary for enzyme activation.

This fertilizer can be used on delicate vegetables and fruit crops that have high rates of fertilization but are sensitive to high chlorine or soluble salt levels. In fact, the max chlorine level of this granular fertilizer is less than 3%, which minimizes the threat of fertilizer “burning” the crops, and the neutral pH does not interfere with soil activity.

This fertilizer is entirely organic; even the box is compostable. The base mineral in it is langbeinite, a naturally mined crystalline mineral that provides the water-soluble sulfate form of its unique potassium, magnesium, and sulfur combination.

#4. Elixir Gardens Muriate of Potash

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The Elixir Gardens Muriate of Potash is another muriate of potash that you can use as a fertilizer to increase the levels of potassium in your backyard soil. This granular fertilizer is highly soluble in water, so it can be used either in its granular form or diluted into a liquid and applied with a spray bottle. Its NPK ratio is again 0 – 0 – 60, which is fairly standard for a concentrated muriate of potash mixture.

This fertilizer is excellent at facilitating the root and stem growth of flowering and fruiting plants and crops, lawn grasses, and can help root vegetables like potatoes, carrots, and squash grow healthy, strong, and fast. It is very potent, so for fertilization uses it is best to apply it at a rate of 5-10 grams per square meter. First, make sure your soil is moist but not fully wet, and spread it out over the ground and then rake it in to the top 3-5 centimeters of soil, before watering the ground again.

#5. Winchester Gardens Select Organics Potato Granular Fertilizer

Winchester Gardens NPK 6-3-9 Select Organics Potato Granular Fertilizer, 3-Pound
  • NPK Composition: 6-3-9
  • Great for sweet potatoes, bakers, boilers and reds
  • Encourages all-around growth
  • Includes spoon
  • 3 Lbs. package

The Winchester Gardens Select Organics Potato Granular Fertilizer is a great fertilizer if you are growing potatoes or root vegetables in your vegetable plot or garden that need potassium to thrive. This fertilizer has potassium sulfate in it, which is highly effective at delivering potassium to vegetables and plants, which they need to grow healthy and strong.

It has an NPK composition of 6-3-9, meaning it contains 6% Nitrogen (N), 3% Phosphorus (P), and 9% Potassium (K) in its compound, and it includes a spoon and a 3-pound bag upon ordering. 

This Select Organics Potato Fertilizer is great for almost all types of potato, including sweet potatoes, bakers, boilers, and red potatoes, as well as other vegetables with similar properties, such as carrots, onions, or asparagus. The high amount of potassium also means the veggies will be better at absorbing the nitrogen, phosphorus, and other vital nutrients.

It has Potassium Sulfate as its main ingredient, which encourages all-around growth and particularly enhances microorganism growth. This fertilizer is all natural and organic and helps to improve soil quality in addition to keeping your plants and soil thriving.

#6. Humboldts Secret Golden Tree Additive

Humboldts Secret Golden Tree: Best Plant Food for Plants & Trees - All-in-One Concentrated Additive - Vegetables, Flowers, Fruits, Lawns, Roses, Tomatoes & More (8 Ounce)
  • FOR ANY PLANT: Our Golden Tree formula is an all-in-one additive for any plant, tree, flower or bush. When used with a well-balanced fertilizer, Golden Tree helps improve soil/foliar nutrient conditions for better crop yields. In addition to improving overall plant nutrition, Golden Tree supports conditions for better plant establishment, nutrient uptake and abiotic stress tolerance.
  • GROW METHOD COMPATIBLE: No matter what grow method you’re using, Humboldts Secret Golden Tree solution will help feed growing plants. It’s designed to be compatible in all mediums - hydroponics, aeroponics, coco, DWC, soil, and every other type of growing method.
  • ESSENTIAL NUTRIENTS: Golden Tree can help provide essential nutrients to your garden that it isn't getting now. Our formula contains a mixture of kelp, carbs and minerals. It can be used in conjunction with other additives and fertilizers or as the only additive.
  • SMALL & STRONG: Our 8-ounce solution makes up to 112 gallons of an easy-to-use additive solution to feed your plants. This is a professional-quality fertilizer that can transform any home and garden and give anyone a green thumb!

The Humboldts Secret Golden Tree Additive is the final fertilizer on our list of best fertilizers for soil lacking in potassium. While this is not a full-fledged fertilizer in itself, it is an additive that, when used in conjunction with a fertilizer, helps to improve the nutrient conditions of soil and foliage, leading to better crop yields and supporting conditions for better overall plant establishment, as well as nutrient uptake and abiotic stress tolerance.

It contains a carefully curated mixture of kelp, carbs, and minerals, so this additive will provide essential nutrients that your plants might not be getting otherwise. It has an NPK ratio of 0 – 0 – 2.

Humboldts Golden Tree is compatible with many different vegetable growing methods, so you don’t need to change your routine when adding it in with hydroponics, aeroponics, coco, DWC, soil, or any other medium. One 16 ounce bottle of this additive can make up to 224 gallons of solution that will last a long time and will continue to feed your flowering plants and garden vegetables for years.

To Sum Up

As you can see, there are many factors to consider when choosing a fertilizer. What works for one type of plant may not work for another. It is important to do your research and find the right product for your needs.

However, we hope that this article has provided you with a good starting point and given you some ideas about which high potassium fertilizers might work best for you. If you would like our top recommendation, it would be the Simple Lawn Solutions High Potassium Lawn Food Liquid Fertilizer.

If you have any questions or need more help choosing the right product, don’t hesitate to reach out to us. We are always happy to help our customers find the perfect solution for their gardening needs. Thanks for reading!

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Written by Linda Chan
Linda Chan is a passionate gardener and writer with a background in horticulture and landscape design. She has over 10 years of experience working in the lawn care industry and has a deep understanding of the science and art of keeping a lawn healthy and beautiful.