5 Easy Ways to Add Potassium to Your Soil for Healthier, Faster-Growing Plants

Potassium is one of the most important nutrients for your garden. It helps vegetables grow faster, and it improves resistance to disease. Without it, plants will weaken, develop brown spots, and pests may even move in.

However, you do have to be careful—too much of it can create a nutrient imbalance. So, how should you add potassium to soil? Ahead, we gathered a few expert methods.

Add a Fertilizer

An easy way to incorporate potassium is with a fertilizer that contains plenty of it. Fertilizer is easily absorbed into the soil; even homemade ones will deliver this key nutrient to your plants' roots.

To be successful, apply either a liquid or granular fertilizer during the growing season, says Angelika Zaber, a lawn care specialist and gardening expert at Online Turf. Preferably in spring.

Use Compost

Compost made from food byproducts is known for its high potassium content.

“However, compost tends to take longer to release nutrients into the soil than fertilizers do,” says Zaber. This is because the byproducts must decompose, a process that can take a long time. “Also, if you decide to make compost yourself, it can take anywhere from six months to even two years to decompose.”

For best results, when creating compost, focus on using potassium-rich materials, such as banana peels, spinach, and tomato waste. Then, apply the finished product evenly to your soil.

Pepper in Wood Ash

Wood ash from fireplaces can also add potassium to the soil. However, it should only be applied in small amounts.

“Adding too much can damage the plants by making the soil too alkaline," says Zaber. Add it to your compost pile every now and then, or apply it directly to the base of your plants’ soil in winter and dig it in.

“This will let it react with moist soil, allowing any compounds in the ash that could scorch the plant to be rendered harmless before the growing season starts," she adds.

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Apply Seaweed or Kelp Meal

Seaweed and kelp meal are packed with potassium. Both are fantastic ways to get slow-release potassium into your garden, says Ward Dilmore, founder of Petrus Landscape.

“Each has the added benefit of containing multiple micronutrients, like calcium and magnesium, which can help improve your soil overall,” he says.

Buy kelp meal or liquid seaweed extract from garden centers, and apply it in loose layers around garden plants, keeping it a few inches from the plant stems to prevent rot.

Use Banana Water

Banana water is easy to make and simple to use. Drying banana peels, grinding them, and applying the powder to your plants will add plenty of potassium to the soil. "Some homeowners can even use this method for houseplants in containers,” says Dilmore.