What Does Potash Do For Grass and Soil?

There are a few essential nutrients necessary for a healthy lawn, and one which often goes overlooked is potassium. 

Potash, named for an outdated method of production where potassium was derived from wood ashes baked in a kiln (hence the name “pot-ash”), has many benefits as a fertilizer for your grass and soil.

Potash is best applied as a winterizer fertilizer for your lawn during the fall and winter. It both heals damage done to your grass and soil over the summer and strengthens it for the harsh winter months ahead by replenishing potassium lost over time.

Keep reading to learn more about potash, its benefits for your lawn, and how to use it. 

We’ll cover everything you need to know about this unique fertilizer. 

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What Is Potash?

Potash, or fertilizer potassium, is the name for a group of potassium-rich minerals primarily used to boost potassium levels in soil for various agricultural production processes. Its most common form is potassium chloride, which is used for various types of plants and crops.

Interestingly, potash is the first chemical patented for industrial use back in the late 1700s. 

Though its production and mining methods have changed over time, its name refers to the original way it was derived from the ashes of wood baked for long hours in a kiln or a large ceramic pot.

Potash is helpful as a mineral fertilizer because it replenishes lost potassium in soil depleted by grasses, flowers, crops, and other plants. 

As potassium gets used up by the grasses and other plants in your yard, your lawn will become weaker and turn yellow or even brown.

Additionally, potassium protects plants from harsh temperatures, lawn diseases, and many common insect pests. 

Without it, your lawn becomes susceptible to these stressors and becomes significantly weaker over time.

If low iron is your soil’s problem, check out our article on how to use Ironite for lawns.

What Does Potash Do For Grass and Soil?

Potash replenishes essential minerals, namely potassium, absorbed by your soil over time. It not only protects your lawn from damage done by harsh winter temperatures, lawn diseases, and insects but also improves the overall health of your grass and other plants in general.

Potash is a fertilizer known as winterizers, meant to be applied at the end of the summer or mid-fall. 

These types of fertilizers prepare whatever plants they are applied to for the cold, rough winter months (in this case, your lawn) by adding lost potassium to the soil. 

In turn, this strengthens the soil by boosting its immunity to disease and overall cold hardiness and making it more durable and less prone to damage.

In addition to potassium, potash contains small amounts of other minerals needed for healthy plant growth, including: 

  • Zinc
  • Copper 
  • Manganese

This combination of minerals will also help strengthen your lawn against all types of damage commonly done to it in the winter, from root damage to wilting from frigid temperatures.

When Should You Apply Potash To Your Lawn?

Although potash is safe to use all year long, it’s best to apply it to your lawn during the fall or early winter before temperatures become very cold and damaging to various plants. Potassium-deficient lawns tend to turn yellow and wilt and are generally very sensitive to temperature fluctuations.

While the only definitive way to tell if your lawn is potassium-deficient is to do soil testing, there are plenty of ways to loosely gauge your lawn’s potassium content just by looking at its overall health. 

As discussed earlier, soil low in potassium tends to produce fragile plants with frail roots prone to damage and wilted yellow or even brown leaves.

Additionally, potassium-deficient lawns tend to be more prone to: 

  • Lawn diseases
  • Pests 
  • Slow growth

If you’ve noticed an uptick in damage or a slower growth rate overall, it’s probably time to boost your lawn’s potassium levels.

If you’ve determined your lawn is desperately in need of potassium, you should apply potash to it as soon as possible, regardless of the season. 

If you’re using it more for preventative maintenance to keep winter damage at bay, however, simply apply it to your lawn at the end of the summer or at least at some point in the fall before winter hits.

Check out other ways to keep your grass from dying.

How Do You Add Potash To Soil?

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Most commercial potash fertilizers are safe to apply directly to your soil. In general, you should use around 15 to 20 pounds of potassium fertilizer to every 1,000′ square feet of severely potassium-deficient soil you want to cover.

There are various methods of applying potash to your lawn’s soil, from using actual wood ash to potassium-rich seaweed or even natural compost. 

The most popular, inexpensive, and accessible method is to simply use commercial lawn fertilizers. 

We recommend something like Greenway Biotech’s Potassium Chloride Fertilizer

While there are many formulations of potassium fertilizers, as we covered earlier, potassium chloride is the best and most widely available option for most lawns needing a quick boost of potassium. 

Simply apply it to raked soil at the end of the summer to prevent damage in the fall and winter, or use it a few times year-round if your lawn is desperately low on potassium.

How Often Should You Use Potash?

For most lawns, applying potash biannually is best, or once during the spring and again in the fall. However, if you’ve determined your lawn is severely potassium-deficient, you should apply it to your soil at least once every season.

Determining precisely how much potash your soil needs is often a bit tricky. 

The primary method of determining your lawn’s potassium and other nutrient levels is via soil testing. 

For example, products like Luster Leaf’s Rapitest Kit For Soil pH test the levels of various essential nutrients in your soil, namely potassium (potash), phosphorus, and nitrogen.

However, as we touched on earlier, there are a few simple ways to loosely gauge the potassium level in your soil without necessarily having to test it. 

This is especially true for potassium-deficient lawns, as the symptoms are apparent even to the naked eye. 

For example, is your grass turning yellow or brown after every winter? 

Are other plants and flowers in your yard wilting excessively, or are they generally just frail when it comes to harsh weather damage? 

Are pests eating away at your lawn more than usual?

If so, apply potash to your lawn at least once at the end of summer to boost potassium content. 

In general, 5 to 10 pounds of potash is ideal for every 1,000′ square feet of mildly potassium-deficient soil, while 15 to 20 pounds is best for lawns with severe damage from a lack of potassium. 

Again, a soil testing kit will inform you of just how severe your lawn’s potassium deficiency has become and give you a more precise idea of how much potash to use.

Can You Use Too Much Potash?

Like with any nutrient necessary for a healthy lawn, there is always the possibility of too much of a good thing. Lawns with too much potash tend to develop nitrogen or other nutrient deficiencies. The best way to tell if you’ve used too much potash is to do a soil test.

Although soil testing is rather tedious and a bit of a pain, it’s still a good idea to test your soil at least once or twice a year to get an idea of your potassium, nitrogen, and phosphorus content. 

If you use too much potash, your lawn will likely develop other nutritional deficiencies because the excess potassium will interfere with how your grass absorbs nutrients.

While potash is extremely helpful for your lawn and soil’s development, using too much of it will still damage your lawn and affect your grass’s overall health and appearance. 

If you find your lawn turning yellow or brown or is still weak and overly prone to damage after applying potash, conduct a soil test with some soil samples to determine roughly how much of certain nutrients your lawn needs.

In the above case, you’ve likely either applied too little or too much potash, and you’ll need to test the soil’s contents to determine which is the case. 

Other than this, you’ll merely be guessing what your lawn needs, which is often risky and will end up damaging your lawn even further.

Does Potash Move In Soil?

In soil with heavy sand content, potash is fairly mobile. However, potash is mostly immobile for most other soil types, or somewhere between nitrogen and phosphorus in terms of its overall mobility. Increasing the moisture level of your soil is the main way to boost the mobility of your potash.

Since potash isn’t very mobile, you should make an effort to apply it as deeply as possible.

Keeping your soil moist is essential after applying potash to boost potassium’s mobility, increase nutrient uptake and root growth, and keep your lawn healthy.

Although potash isn’t quite as immobile as nitrogen, it doesn’t move as quickly or deeply into your plants’ roots as the far more mobile mineral phosphorus does. 

Frequent watering after applying potash will increase its mobility and encourage it to reach the roots of your grass, crops, or other plants.

Can You Make Your Own Potash?

There are a few clever ways to make your own potassium fertilizer. The most popular method is to use wood ashes, though potassium-rich banana peels and seaweed are also used. Still, commercial potassium fertilizers are far easier to acquire and are inexpensive if you don’t want to make it yourself.

Let’s go over a few ways to make potassium fertilizer on your own at home. 

Again, keep in mind these methods are somewhat time-consuming and are far more tedious than simply buying commercially mass-produced potash, so be prepared to put in a lot of effort for a relatively small amount of fertilizer. 

The first and most popular method is to simply use leftover wood ashes, as they are an excellent source of potassium. 

Whether or not you have a fireplace or a fire pit, this method will be convenient for creating a small amount of potash from time to time or not available to you at all. 

This method hearkens back to the original way potash was developed (hence the name, “pot-ash”) by deriving it from the ashes of wood fired in a large pot or kiln. 

You’ll need to make sure you filter out any wood chips or other debris and only use the ashes left over after burning the wood.

Another important thing to remember here is the precise amount of potassium in the ashes will vary depending on the wood used, where it came from, how long it is fired, and other environmental factors beyond your control here. 

Hardwood such as oak or hickory works best as they produce a lot of ashes.

After you’ve isolated the ashes, you have the option of either applying it directly to your soil from here or refining it a bit more. 

Refining the potash is a relatively short and simple process. 

It is recommended to eliminate any contaminants or materials you don’t need, which would potentially interfere with your soil’s nutrient content.

From here, to refine the potash, pour the ashes into a bucket (non-metal is best). 

Add water to the bucket until the mixture reaches the top, use a strainer or a similar device to remove any solid material left over, and stir it. 

Repeat the process if you notice any more solids rising to the surface.

After you’ve skimmed off the top, let the bucket sit for a few hours to let the ashes separate. 

Eventually, you’ll be left with the water on top, which you should gently pour out without disturbing the material at the bottom. 

Then boil this water down until only the potassium carbonate is left over. 

This material is your homemade potash!

It’s best to use a small portion of the potassium carbonate on a small test portion of potassium-deficient or very acidic soil and then test the soil afterward to gauge approximately how much potassium has been added.

From there, you’ll be able to apply the ashes to larger areas of your soil, needing a boost of potassium. 

Generally, around 10 to 15 pounds of wood ashes per 1,000′ square feet of severely potassium-deficient soil is best. 

This level is similar to other potassium fertilizers.