Potassium, along with phosphorus and calcium, is a very important plant nutrient for overall health. It’s involved in protein synthesis and in the flow of nutrients and water up and down the plant. Potassium strengthens plants against cold, heat, disease, and pests, and it’s the key ingredient in fertilizers labeled as “winterizers.”
If you’re looking to go organic, there are many ways to supplement your lawn or garden with potassium without using chemical fertilizers — read this guide to learn about them.
The Top 8 Organic Sources of Potassium for Your Yard
Here are the most common sources of organic potassium:
Compost
Compost is full of nutrients, including potassium, especially if it is beefed up with banana peels and other fruit and vegetable waste. The potassium compounds in compost are water-soluble, which makes them readily available to plants, preventing potassium deficiency, but also likely to leach out of your compost pile over time.
Wood Ash
The original source of “potash” fertilizers, hardwood ashes, can be used directly as a fertilizer (about a 5-gallon bucket per 1000 square feet) or added to your compost pile to increase the potassium content. Wood ash also raises soil pH, so be sure to do regular soil testing to make sure it stays balanced.
Kelp Meal
Available dried or liquid, kelp, and seaweed offer potassium to the soil in a fairly quick-release form.
Greensand
It is made from ancient former sea beds and is rich in a number of minerals, including potassium. It’s used both as a fertilizer and a soil conditioner, or it can be mixed with compost.
Muriate of Potash (Potassium Chloride)
Mined from ancient deposits, this commercially available product can be used as a natural source of potassium, though the chlorine found in it can harm soil microbes.
Sulfate of Potash (Potassium Sulfate)
More expensive than muriate of potash but safer since it doesn’t contain chlorine. Not all potash products are considered organic, so make sure the product you use is approved by the Organic Materials Review Institute (OMRI).
Sul-Po-Mag
A variation of potash, Sul-Po-Mag is actually a naturally occurring mineral called langbeinite (sulfate of potash-magnesia). Sul-Po-Mag is water soluble and convenient, although it shouldn’t be used unless your soil also needs sulfur and/or magnesium.
Granite Dust
Available from granite quarries, granite dust is a relatively inexpensive way to add potassium and tract minerals to your soil. Since it’s ground-up rock, this product is a very slow release and is not a quick fix.
The Benefits of Organic Potassium Sources for Your Plants
Organic sources of potassium offer several advantages over synthetic fertilizers. They release nutrients slowly, reducing the risk of nutrient burn and promoting long-term soil health. These natural options also improve soil structure and microbial activity, enhancing overall plant resilience.
Besides being a great soil amendment, organic potassium sources often contain other beneficial minerals and trace elements, providing a more balanced nutrition profile for your plants, lawn, and vegetable garden.
How to Apply Organic Potassium to Your Lawn or Garden
Applying organic potassium sources requires a different approach than using synthetic fertilizers. For compost and wood ash, spread a thin layer over the soil surface and gently work it into the top few inches.
You can apply liquid kelp as a foliar spray or soil drench. When you use mineral sources like greensand or granite dust, incorporate them into the soil before planting or topdress existing plants. Always follow the recommended application rates and perform regular soil tests to monitor potassium levels.
Final Thoughts
There are numerous organic sources of potassium available for your lawn or garden. From compost and wood ash to specialized products like kelp meal and greensand, these natural options provide a sustainable way to nourish your plants while providing other micronutrients.
By using these organic potassium sources in your gardening routine, you’ll not only promote healthier plant growth but also contribute to long-term soil health.
Frequently Asked Questions
How often you apply it depends on your soil’s needs and the specific source used. Generally, apply organic matter potassium fertilizer once or twice a year, ideally in spring and fall, based on your soil test results.
Yes, banana peels are a good source of potassium. You can bury them near plants or add them to your compost pile for an organic gardening potassium boost.
Wood ash is beneficial for most plants but should be used cautiously with acid-loving plants as it can raise soil pH. Always test your soil before application.
Further Information
- Fertilizer 101
- The Debate Over Organic vs. Chemical Fertilizers
- Planet Natural (organic fertilizers available online)
