Scoria vs Pumice: Pros and Cons for Growing

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Last Updated on March 2, 2023

Today we are going to discuss scoria vs pumice for soil amendment in succulents. They are both minerals that are widely used in gardening, but for different things. Some people argue if they are good for succulents and why. Let us discuss their pros and cons.

Growing succulents is very popular, and I have a soft spot in my heart for them. They are so easy to keep, as they usually prefer negligence rather than constant attention, and they look so nice when correctly displayed. This, though, can be intimidating for an avid gardener, as one may think that it is outrageous to leave the plants be and not care for them that much. But that is exactly what succulents need. The best way to make sure succulents can thrive in your garden is to choose the right soil for them. 

What Type of Soil Do Succulents Need?

Growing succulents in areas where the soil is not their preferred type to grow in can be challenging if you do not know what they need to thrive. The main issue you may run into is overwatering. 

What happens is that not any soil will work with these plants. They are a type of cactus, so they do not need much water at all to live. If you plant them in moist soil, they will die, although that may seem counterintuitive to some gardeners.

Scoria and Pumice: Pros and Cons for Succulent Growing

The first thing to know is that you need a well-draining potting mix. That means, it needs to be a porous type of soil and it needs to drain water really well. If it traps water, you will drown the plants.

You can buy a pre-packaged succulent soil mix or a porous soil mix, but it is cheaper to make your own. This way you can also control all the ingredients that go in it and assure yourself you will not overwater the plants.

What is Scoria?

Scoria is a small grain of red lava. It can be found coarsely or finely milled, like sand. It is formed in basaltic magma, which means that it comes from lava that is flowing. It is a type of rock that has many air bubbles trapped in it and that is why, when milled, it remains porous. 

Its color makes it very beautiful and it is usually used in landscaping. Many people prefer the flashy red look of it to decorate their gardens.

Is scoria good for planting succulents?

As a soil alternative, 100% scoria is not the greatest idea for succulents. It has higher-than-expected water retention which is associated with the high surface area and little holes that the rocks have. This makes it heavy and can lead to succulents dying from overwatering.

If you are going to add scoria to your planting mix, we recommend using a larger ground and washing all the dust before mixing it into the soil. The dust can prevent airflow and trap too much-unwanted moisture next to the roots.

This could also be detrimental, though, because the larger it is, the more chance it has of damaging the roots of your succulents. It has sharp edges and a heavy root.

What is Pumice?

Pumice is the preferred type of lava rock that is used as a soil amendment for succulents. It is different from scoria in that this rock is formed from the actual eruption of a volcano. Its reaction to air and extreme heat then creates a froth that then becomes a felsic rock. That is pumice.

Felsic means that it is composed of light minerals, so it is lighter than scoria. It is white and that is why many landscapers prefer scoria to finish up their garden look. But this color difference means that it is composed of different minerals and has different, although similar, properties.

Is pumice good for succulents?

Pumice has 70 or more trace minerals that are readily accessible to plants because of its thin layers. It is volcanic glass and not rock. This is why it is lighter than scoria, which is a rock. Pumice will float when first dropped into water, for example.

After a while, it will sink, though. This is because all of its little nooks and crannies will hold water. This is also what happens when you water pumice-rich soil. Pumice will hold water and slowly release it as the plant needs it.

It will seem bone dry to the touch but it’s holding moisture, just not right next to the roots, which can lead to rotting.

what is pumice

What is Scoria and How Does it Differ From Pumice: Scoria vs Pumice 

As mentioned, both scoria and pumice are types of volcanic rock. However, scoria is much darker in color and is usually red, black, or brown. The comparison between the two is that while pumice is light in color, scoria is dark in color. While pumice is low in density, scoria is high in density. While pumice has small vesicles, scoria has large vesicles. And while pumice has thin vesicle walls, scoria has thick vesicle walls. However, their similarities are that they’re both volcanic rocks and they both may contain crystals.

Scoria Texture – What is it Like?

You may be wondering what the texture of scoria is like. Both scoria and pumice rock have a vesicular texture. This simply means that it contains holes.

Pumice and Scoria Rock Type – Are Pumice & Scoria Igneous Rock?

There are many types of rock and you may be wondering what types of both pumice and scoria are. Both pumice and scoria are types of igneous rock; which simply means they’re made from molten lava. They’re both vesicular in texture and come from volcanoes. While scoria is usually red, pumice is most often white.

What Plants to Use Scoria For?

You can use scoria in your soil for many plants. However, I’ve found that it works best for garden beds and plants such as tomatoes, flowers, and herbs.

What Plants to Use Pumice For?

You can use pumice in your soil for plants such as succulents and cacti. If a plant needs good drainage, then pumice is sure to help. You can also use pumice for flower beds, vegetable gardens, and flower pots. However, for smaller plants, it’s best to use finely crushed pumice.

Benefits of Using Pumice 

There are many benefits when it comes to using pumice in your gardening. Let’s take a closer look at why you should add this rock to your list of gardening essentials.

  • Pumice is Heavy. While this may seem like a drawback, it’s absolutely not when you’re working with plants that are top-heavy and need that support and structure to thrive.
  • Helps Waterlogging. As pumice is often recommended for plants that require good drainage, they’re great at ensuring your plants aren’t drowning and potentially rotting. Pumice’s main function is that it retains any water your plants do not need to thrive.
  • Versatile. Pumice can be used in any type of soil, so is a staple for your gardening needs. As well as this can also be used as mulch, as it’s hardy and can last for long periods.

Benefits of Using Scoria

There are also many benefits of using scoria in your gardening. Let’s take a closer look.

    • Great Water Retention. Much like pumice, it can be helpful for plants that require good drainage. This is an ideal environment for many plants to thrive; particularly if you have a lot of rainfall or waterlogging issues.
    • Protection. As scoria is a hardy rock, it works great as mulch and provides a protective barrier to your plants, from issues such as erosion.
    • Less Care. To keep maintenance of some soil can be hard work, but this is not the case for scoria. It requires little effort at all as it’s so long-lasting.

Conclusion: Scoria vs Pumice 

Both of these ingredients will lighten the soil, but pumice will hold more air and water than scoria does, while at the same time providing lightness to the soil and not damaging any roots or leaving the plants open to infections.

Another thing is that scoria is rich in fluoride. Succulents do not like this component in their soil, they are really sensitive to it. This is why it is not recommended to water succulents with tap water, especially if you live in a city.

Scoria is great to use as a topper. It looks amazing and prevents pests, insects, and rodents from coming near your plants -to an extent. Pumice is best to add to your soil because of its many benefits.

Scoria is still going to be a better option to add to your soil than aquarium gravel or pea gravel because it is going to be a lot more porous. These are more space fillers and do not provide aeration. 

If scoria is more readily available to you, try it out! Bear in mind that, as it is heavier, if you use it in bigger pots they are going to be more difficult to move around. It should be fine to try in smaller pots. Do not try it with young plants, though, as they need to keep moistened for the first year.

What is your favorite type of additive to grow your succulents or other plants? Leave a comment below with your tips and tricks, we would love to know and share them with the community!


Is Perlite or Pumice Better For Succulents?

Both perlite and pumice are great for succulents. However, pumice may a better option only if they are meant for taller plants. Pumice weight will provide an anchor that will prevent your pot or container from being overturned or capsized. Pumice is also durable and heavier material than perlite.

However, pumice may be difficult to purchase and they are higher in price than perlite.

Succulents require adequate drainage; this is where perlite and pumice come in. Both perlite and pumice are soil amendments for succulents mixed with potting soil to enhance soil aeration and excellent water drainage.

Where Can I Buy Pumice Plants?

Here are the following places you can buy pumice for your plants from:

-You can find a vast variety of pumice for your gardening needs from the Amazon online shopping store.
-You can also buy pumice from stores like Walmart, Lowes, Home Depot, etc.
-Hess pumice offers various grades of pumice products that you can also buy in various garden centers closer to you.

How Do You Apply Pumice to Plants?

You can notice enough soil improvements by combining as little as 10% pumice with your garden soil mix. To enhance the porosity of plants such as succulents, apply 25% pumice mixed with 25% soil. You should also mix 25% compost and 25% large-grain soil. To improve soil drainage for plants that are susceptible to root rot such as euphorbia, mix 50% pumice with potting soil. Ideally, the general rule is to combine an equal amount of pumice with potting soil for potted succulents. For cacti plants, you can mix 60% pumice with 40% potting soil. You can also use pumice as a top dresser to mop up stagnant rainwater around plants.

Is Lava Rock the Same as Pumice?

Lava and pumice are of both volcanic origins. They are however slightly different. They differ by color, density, element composition, vesicle size, and water retention capacity.

Pumice is lighter because of the air mixed in it, while lava rock is denser. Lava rock also has bigger vesicles and thicker vesicle walls than pumice.

Lava is a type of scoria rock and it is a molten rock released from a volcano during an eruption. The subsequent rock solidifies and cools to result in lava rock, while pumice is a mixture of volcanic ash and rock.

Lava rock, just like pumice, is great for enhancing drainage and they are great for succulents. However, pumice comes in a better size and structure for your plant use.

What Causes the Frothy Appearance of Pumice and Scoria?

The frothy appearance of pumice and scoria is caused by the aggressive eruption from volcanic which shoots the lava out filling it with gas.

Both pumice and scoria are extrusive rocks. They are usually molded outwards of the volcano, especially at the upper part of the lava flow. The upper part of the scoria turns extremely frothy and after they must have cooled down. The air in the lava then expands and breaks free creating an air hole in the rock.

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