6 Ways to Add Potassium to Your Soil - Backyard Boss
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6 Ways to Add Potassium to Your Soil

For healthy plant growth, you must keep an eye on three essential nutrients in your soil: nitrogen, potassium, and phosphorus. There are many ways to add phosphorus to your soil and effective ways to add nitrogen.

Potassium is just as important as it helps plants absorb nutrients from the soil to form plant protein. Besides that, potassium acts as a shield that protects plants from frost, drought, diseases, and pests. If you don’t want to purchase commercial potassium fertilizer, how about making one yourself? Discover how!

Why Your Soil Needs Potassium

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Besides nitrogen and phosphorus, plants need potassium for healthy growth. This is because potassium balances water and gas exchange in the soil and regulates root pressure. It also accumulates in the plant cells and makes the cell sap saltier, which acts as a natural antifreeze when temperatures drop. Potassium:

    • Ensures optimum water utilization and reduces drought stress, which increases a plant’s stability.
    • It helps form important sugar compounds and transports them from the leaves to other parts of the plant.
    • Increases the vitamin content in fruits and vegetables. For example, tomatoes and other fruits won’t taste as good when they have a potassium deficiency.
    • Strengthens plant tissue, making them resistant to pests and diseases.

Because a potassium deficiency can be hard to spot, and too much potassium can cause stunted growth, it’s essential to test your soil before adding potassium to your garden.

How to Add Potassium to the Soil

If you want to make potassium fertilizer for your soil instead of purchasing one online, learn six practical ways to do so.

1. Comfrey Liquid Manure

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Comfrey is an excellent source of potassium. You’ll need 2 to 4 pounds of comfrey leaves and 5 gallons of water to DIY a comfrey potassium fertilizer. Add the leaves and water to a large bucket, mix well, and let it sit for two weeks in hot weather or four weeks in cool weather.

After two or four weeks, strain the leaves and squeeze them to extract as much liquid as possible before adding them to your compost pile. To use comfrey fertilizer, mix 2 pints of comfrey juice with 5 gallons of water before using it in your garden.

You can use it as foliar spray or drench your soil with it to improve its potassium levels. Comfrey leaves contain about three times more potassium than farmyard manure!

2. Dandelion Liquid Manure

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Dandelions are also a fantastic source of potassium. To make dandelion potassium fertilizer, you need about 4 pounds of dandelion flowers, leaves, and 5 gallons of water. Like comfrey preparation, soak the dandelion leaves and flowers in a large bucket of water for three to four weeks.

After the weeks have passed, strain and squeeze the flowers and leaves to extract as much juice as possible. Toss the remaining solids in your compost pile, then dilute 2 pints of dandelion juice to 5 gallons of water before spraying in over your plants and soil.

3. Fern Broth

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Bracken Fern (Pteridium aquilinum) is rich in potassium. So much so that the plant’s ashes can be used as fertilizer. In early summer, this fern’s roots contain about 20 percent potash! You can make fern broth for your garden to improve the soil’s potassium levels.

To make your broth, you’ll need about 10 pounds of fresh fern or 2 pounds of dried fern and 2.5 gallons of water. Soak the fern daily and boil the mix for about half an hour. The fern broth mobilizes the potassium from the compost and the soil and can also be used against aphids.

4. Coffee Grounds

Coffee grounds
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Give your coffee grounds a second chance by letting them work their magic on your soil. Besides nitrogen and phosphorus, ground coffee also contains some amounts of potassium and other micronutrients, including calcium, magnesium, and copper. There are three ways to let coffee improve your soil’s potassium levels:

  1. You can add coffee grounds to your compost pile and use the matured compost in your garden.
  2. Directly sprinkle coffee grounds on your soil as mulch or top dressing. Apply no more than one-half inch of ground coffee and work it into the top two to three inches of your soil.
  3. Make coffee “tea” by adding two cups of used coffee grounds to five gallons of water. Let the mixture brew overnight, and then use it as fertilizer for your garden.

That said, coffee grounds are acidic (pH level 6.5 to 6.8), so you may want to test your soil’s pH and amend it accordingly.

5. Banana Peels

banana peels for soil
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One ripe banana contains 450 milligrams of potassium! Like people eat bananas for potassium, plants benefit from the fruit too. But to let it work its magic, bananas must be able to decompose into the soil quickly.

To help bananas decompose quickly, chop them into tiny pieces, then work them into the top 2 to 3 inches of your soil. As a rule, use about 3.5 ounces of chopped bananas per plant.

You can even make banana tea by chopping the peels into small pieces and letting them soak in water for two to three days. Add four parts water to one part banana peel to make this tea.

6. Wood Ash

wood ash in soil
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If you have a fireplace, use the wood ash as fertilizer instead of disposing of it. However, ensure the wood you use is untreated, free from chemicals, and hasn’t come in contact with industrial residues.

Besides phosphorus, magnesium, and sodium, wood ash has nearly four percent potassium. Wood ash is also a liming agent and can increase soil pH. Before handling wood ash, wear protective gear, goggles, a mask, and gloves.

You can spread wood ash directly to your vegetable patch, but be careful not to add more than 15 to 20 pounds of wood ash per 1,000 square feet annually. If it’s too windy outside, spreading ash can cause you to ingest it accidentally.

To avoid that, add wood ash to the irrigation water and use it in areas you want to improve potassium levels. You can add a thin layer of cooled wood ash to your compost pile to boost nutrient levels. That said, wood ash should only make up five percent of your entire compost pile.

Testing your soil and soil pH before adding wood ash is essential. This is especially true if you’re growing acid-loving plants like orchids, pineapples, or blueberries.

It’s O-K!

Potassium is one of the most important nutrients that plants need for healthy growth. There are many ways to add potassium to your soil, so you’ll need to find out which method works for you, depending on the type of plants you grow.

However, before adding potassium to your garden, you must test your soil to ensure you’re not adding too much because an excess can cause stunted growth.

Leave your experiences, thoughts, and questions in the comment section! And share with friends and family who might find this helpful.