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Scoria and Pumice: Pros and Cons for Succulent Growing

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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 they can thrive in your garden is to choose the right soil for them. 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.

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 prepackaged 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 red lava. It can be found coarsely or finely milled -like sand. It is formed in basaltic magmas, 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 a 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.

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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 is 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 to 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 in color 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 actually 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 a 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 its holding moisture, just not right next to the roots, which can lead to rotting.

Conclusions

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 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!

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