What is horticultural grit? (Experts explain)

As we all know, plants require certain conditions to grow and develop efficiently. Landscapers and farmers all across the globe continue on the never-ending path of learning and implementing strategies to meet these conditions for our decorative plants as well as food crops.

Horticultural grit is crushed or pulverized pieces of gravel. Many times it is made from granite while other times it is taken from other types of stone. It is used to bring stability to soils in order for them support plants and not collapse in upon itself.

One of these strategies is the use of horticultural grit, which is our focus today. Join us as we take a look at what it is, how it can help your gardening or agricultural pursuits, as well as some viable alternatives.

Let’s start by looking at what the term “horticultural grit” actually means.


What Is Horticultural Grit And What Is It Used For?

The materials vary, but granite is the most common. Several other rocks can be used as grit but there are several advantages of using granite. With that said, what exactly is horticultural grit and why is it popular with gardeners?

Horticultural grit is little bits of washed gravel and stone particles that are about 1-7mm (or 0.04-0.28 inches) in diameter. The grit is mainly used for potting mixes, but large-scale crop farmers have also incorporated it to boost yields. In essence, it is a form of soil conditioner.

Horticultural grit is used for adding stability and structure to the soil to prevent it from falling in on itself. This keeps the ground level and consistent, which makes it better for sustaining plant life. 

Horticultural Grit For Air And Water Balance

However, the biggest reason for using horticultural grit is the maintenance of your soil’s air/water balance. Some may not be aware that this can actually be a delicate balance.

You see, plants need water and air (oxygen, more specifically) and the soil must facilitate access to both as and when needed. The roots themselves need both even at their level under the soil.

The soil must be able to retain water so plants can take up as much as possible. However, too much water is a problem because the water will stand and stagnate.

Standing water is a breeding ground for fungi and a whole host of nefarious bacteria. These pests can easily wreak havoc, usually in the form of diseases such as root rot. 

Root rot will inhibit your plants’ ability to take up water and soil nutrients. Lack of nutrition will make plants weak and susceptible to even more diseases.

Horticultural Grit For Drainage

So, too much water is bad news. This is why your soil needs drainage.

Drainage is the rate at which soil allows water to trickle down and away from the root zone. Drainage is also why we need to use horticultural grit when dealing with heavy soils. Compaction can become a huge problem in certain types of soils.

Clay soils, especially, are particularly prone to waterlogging and getting packed down. We in the southern United States know all about having to deal with clay soil. Both of those environments are far from ideal for most plants, especially crop plants. 

Landscapers and farmers mix grit stones in with soil during tilling to break up clumps and create air spaces. The grit will ensure clear passages for developing roots. Seeds, especially, need as much help as they can get as they establish themselves.

In fact, clay soils mixed with grit have been found to be more effective for nursing crops than sandy soils. Sandy soils discharge water at a rate that exceeds the water uptake of plants. They also lack the nutritional content of clay, as well as its temperature regulation capabilities.

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Acidity Vs Alkalinity

Another reason we love grit, especially granite, is pH neutrality. Any soil additive that doesn’t disrupt the soil’s acidity is priceless. For one, this means fewer headaches when mixing fertilizers which often have their pH implications.

On the flip side though, you have grit materials like lime that can impact acidity/alkalinity, if that’s what you’re after. It is important to know your soil before adding things that can change things like pH.

Horticultural grit is also very affordable and can even be sourced for free. Some forms of it also can also be raked out and reused over and over. In cases of disease, the grit can be easily washed and disinfected.

What Can I Use Instead Of Horticultural Grit?

So, with every box horticultural grit ticks off, are there alternatives that may be better? Are there ones that may have drawbacks? Let’s look at some of them.

There are other materials that can be used instead of horticultural grit. Sand, vermiculite, and perlite all can be used as a replacement. Each of these have their pluses and minuses and can do a proper job of stabilizing the soil. Which one you choose will depend on the plants and soil you have.

Sand is a good choice for mixing with heavy clay soils. Doing so properly will provide you with the best of both worlds…clay’s water and nutrient retention, and sand’s permeability and air spaces.

Unfortunately, sand is not reusable because you can’t separate it from the potting mix. However, it will get the job done if regular grit is inaccessible. It is also one of the cheaper options of the list of likely materials.

You can also opt for vermiculite, which is a family of hydrated magnesium, iron, or aluminum silicates with a lot of the same benefits as horticultural grit. In fact, vermiculite is lighter than most stones used for grit, which is a major advantage if your soil is already pretty heavy.

The downside with vermiculite is that it is more difficult to source than regular grit and more expensive as a result. To be honest though, all of these can be purchased for small scale projects for a relatively affordable price.

On the upside, there is an inexpensive bag that gets rave reviews. I suggest the 8QT Professional Grade Vermiculite from Amazon.

You also have perlite, another lightweight alternative to horticultural grit. Like vermiculite, perlite is pH neutral, reusable…and difficult to source. As you can imagine, it is quite pricey.

Is Perlite The Same As Horticultural Grit?

Perlite is little shards of volcanic glass that have been processed into lightweight and super durable granules that are perfect for amending heavy soils. Perlite is a super compound made up of silicon dioxide, aluminum oxide, potassium oxide, iron oxide, as well as magnesium and calcium oxides. 

Perlite is very versatile and can be used as an alternative to horticultural grit, or used alongside it. You can also opt for a vermiculate/grit mix but perlite granules tend to provide wider air channels in soil, while still being lightweight. It also has uses in soils with pH level problems.

Perlite is also pH neutral, an advantage we’ve already looked at. This makes it perfect for nursing delicate plants, seedlings, and seeds. It is used by professional and amateur gardeners alike to produce everything from locally sourced plant life to exotic foliage.

Even though there is a processing stage, perlite is a naturally occurring substance that is not harmful to the environment. There will be no substances leached into the soil or taken from it.

Like horticultural grit, perlite can be taken out of potting mixes and reused. This is great news given the cost of obtaining the material. Again, the cost is relative to horticultural grit in general.

This brings us to the main drawback…price. (Yet, I have found a great deal on an inexpensive bag of Perlite here, on Amazon.)

Supply influences price, unfortunately, and the limited supply means a higher price for you. Being “naturally occurring” also comes with the problem of non-renewability. The world has finite quantities of perlite, which makes it much pricier than granite or lime.

Perlite granules also have films of dust across their surfaces, which is a potential hazard if inhaled. Dry perlite is especially prone to this so you will have to wear masks when working with the substance. You can also hose perlite down with water to combat the dust.

All in all, perlite is recommended if you have a serious issue with soil heaviness and need a once-and-for-all solution regardless of price. For large-scale agriculture, horticultural grit and vermiculate are far cheaper options.

The Final Touches On Horticultural Grit…

Now that we know that horticultural grit is used to give strength and stability to soils by gardeners, we can apply it better in our situations. There are several substitutes that can be used, each with their own strengths.

It is imperative that you take into account your particular soil type and needs before using it. But for those who need it, it can be a great help, especially with temperamental plants.

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Mathew Booe

Mathew has worked in landscaping professionally for over 10 years. He is a grandpa and frequently interviews other experienced landscapers and lawn care experts who are also grandpas for these articles.

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