Vermiculite vs. Perlite – What’s the Difference?
You need a healthy soil to grow beautiful and fruitful plants in your garden. And the good thing is that the there are many things and ways that you can use to upgrade the quality of your soil. From the many soil improvement methods available, soil additives are some of the most popular, and this is because there is enough proof that they are very useful for growing healthy plants.
In your search for the best soil additives, vermiculite and perlite are two names that you can almost be certain that you will come across. The two are ideal additives for enriching the soil while also improving the moisture retention.
Although vermiculite and perlite look similar and serve the same purpose, they are suitable for different situations. And so you need to know the characteristic of each and their pros and cons so as to determine which is ideal for your soil.
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Vermiculite vs. Perlite
Vermiculite resembles mica in its appearance, and it comes in a golden to dark brown shade that makes it hard to identify in a potting mix. It is a silicate that contains aluminum, iron, and magnesium whose main aim is to help the plants retain as much moisture as possible. Vermiculite goes through a heat treatment to expand its particles to enable it to absorb water.
This soil additive can expand up to 4 times its size when it absorbs water and retains it to ensure that the plant will have it when it needs it, and it has a neutral pH of 7.0.
- Retains a Lot of Water: The top benefit of having vermiculite as a soil additive or part of your potting mix is that it absorbs a lot of water. It can expand 3 or 4 times its size by absorbing water, and it ensures that the plants always get the moisture they need to grow well.
- Prevents Soil Compaction: Soil compaction affects everything from a soil's ability to retain moisture to aeration. However, adding vermiculite flakes helps to avoid this because their shape and size (after absorbing water) make compaction almost impossible.
- It is Natural: Vermiculite is a lightweight and naturally occurring compound, and so it will not add any chemicals or toxic residue to the soil. Also, it is a chemically inert compound, and so it will not change the soil pH.
- Poor Soil Aeration: Since vermiculite absorbs more water than perlite, it is a poor aerator, and it will not provide enough oxygen to the plant. However, mixing it with perlite can help to improve the aeration.
- Not Ideal for Some Plants: If you use this soil additive when growing plants that do not require a lot of water or a damp soil you are likely to find them suffering from root rot. And so it does not work well for some plant types.
Perlite is a mined rock that is very rich in silicon. After the mining, it also undergoes a heat treatment to expand its particles so as to make it a suitable soil additive. It is a porous material that resembles white granules, and sometimes people mistake it for some tiny foam balls.
Perlite contains some microscopic bubbles that absorb both water and air. It also drains well which helps with aeration and prevents the soil from becoming damp. This soil additive is clean, lightweight and odorless and it comes with a pH of between 6.6 and 7.5.
- Retains Water and Drains Well: Perlite has a large surface area with some crannies and nooks that help it to retain water. But unlike vermiculite it allows any excess water to drain quickly leaving just enough for the plant.
- Enhances Aeration: By releasing the excess amount of water, perlite helps to improve the aeration of the soil, and this allows the plant to get more oxygen. The microscopic bubbles in this additive also assist in holding more air.
- Higher Humidity: The large surface area of perlite makes it perfect for raising the humidity level in horticulture and mycology. Large size means more evaporation which in turn translates to higher humidity levels.
- Drains Water More Quickly: If you want to grow seeds or seedlings that require a lot of water perlite might not be the right choice for you because it does not retain enough water. Although it absorbs a lot of water, it drains it very fast which means that the soil dries out quickly.
When to Use Vermiculite or Perlite
Perlite and vermiculite perform the same role in retaining moisture, preventing soil compaction and improving aeration but they do it in diverse ways and levels which make them ideal for different situations and plants. The two work well for new seeds and seedling cultivation, but it is important to know what to use and when.
Vermiculite will be a perfect choice for the plants that require a lot of water or a damp environment because it absorbs and retains enough of it. It is ideal for cultivating irises, pickerelweeds, cattails and many other plants that love water. Tropical plants and those that require constant moisture will thrive when using vermiculite.
Perlite creates a well-drained soil and so it will not be suitable for plants that require damp soils. Plants like cacti and Aloe Vera will do well with this soil additive. And this is because they need good drainage. Also, perlite is ideal for plants that may need to dry out and when moving seedlings from one pot or container to another.