If you’ve ever stood clueless at your local gardening center trying to decide whether perlite or vermiculite is best for your plants, this is the right article for you.
Perlite and vermiculite have many similarities but they differ in a few crucial characteristics, which makes them well-suited for different situations.
Our comprehensive guide makes it easy to understand perlite vs vermiculite.
Let’s begin with the basics.
Perlite vs Vermiculite: Overview
Similarities
Both perlite and vermiculite are lightweight substitutes for soilless potting mixes to improve texture and aeration. They offer the following features:
- Seed-free
- Insect-free
- Odorless
- Sterile
- pH neutral
In addition, both media are used as a carrier for dry fertilizer, herbicides, and pesticides.
Differences
Now for the big question: What are the differences between perlite vs vermiculite?
Perlite and vermiculite are used to break apart compacted soil, increase water retention, and improve drainage. However, the difference in how much water they retain makes the two substances better suited for different applications.
Perlite’s low water retention makes it a perfect match for rhododendrons, succulents, or cacti, which require well-drained soil. The use of vermiculite in such situations can lead to root rot or death
Vermiculite is ideal for plants that need a lot of water such as forget-me-nots and irises. Perlite doesn’t retain water as well and dries out too quickly, so it’s unsuitable for such plants.
What is Perlite?
The bag of perlite on that shelf begins its life as volcanic glass, but not just any volcanic glass. It’s formed when obsidian comes into contact with water, creating a unique volcanic glass with high water content. When a perlite manufacturer heats this glass, it pops into white balls. The final product is light and has many tiny nooks and crannies.
These pockets retain water and improve both drainage capabilities and aeration, which are crucial features in hydroponic gardening. Because perlite is porous, it acts as a natural filtration system, draining excess water while retaining some moisture and catching important nutrients required by your plants.
Due to its sterile pH neutral state, perlite doesn’t affect the water or attract pests, which is a constant concern with soil.
You’ll need to regularly replace perlite because the pores can become clogged with roots, algae, and nutrients, but it can be reused because it doesn’t decompose.
Before reusing, pick through the perlite to remove material like root segments. Rinse it thoroughly when you’re done. If sterility concerns you, soak the perlite in 10% bleach for 30 minutes and rinse afterward.
Note: Perlite is often dusty when dry and it’s highly recommended you wear a mask when handling dry perlite. Once wet, the dust shouldn’t be a problem.
3 Benefits of Perlite
Completely reusable
You can always rinse perlite and use it again unless you have a disease floating around and you don’t have any way to sterilize the perlite. For example, with an infection like Pythium, you can wipe out the disease from the perlite and sterilize it with bleach or heat before using it with new crops.
Assists with anaerobic conditions
Since perlite holds air very well, it can help you deal with a lack of oxygen. As you may know, a lack of oxygen can give rise to anaerobic bacteria, which is in no way good for your plant’s roots. Perlite can resolve any present anaerobic zones since the air pockets hold oxygen.
Inert and pH neutral
Unlike peat or coco coir, perlite doesn’t come from an organic source and is superheated during its creation. This means there’s no way fungi, bacteria, or pests can make a home in perlite. It can be a vital and inexpensive form of pest control.
2 Best Perlite Brands To Buy
Hoffman Perlite
| Description | Made by Good Earth Organics, Hoffman Perlite is a lightweight soil mix that focuses on improving aeration and drainage. It reduces the caking of soil and loosens clay soil. It’s suitable for starting seeds, storing bulbs, and propagating cuttings. To make your own soilless mix, blend Hoffman Perlite with vermiculite and peat moss. |
| More Info | View on Amazon → |
PVP Industries Coarse Perlite
| Description | If you’re looking for professional-grade perlite, you can’t go wrong with PVP Industries. This perlite has an increased nutrient holding capacity if water-soluble fertilizers are used, and because of its light weight, root systems and fine stems aren’t damaged. This makes it suitable for delicate plants like lettuce. |
| More Info | View on Amazon → |
How To Use Perlite In Hydroponics
Since perlite doesn’t retain much water, efforts must be taken to keep roots continuously wet. If you plan to use perlite alone, a drip system or bucket system will function better than an ebb and flow system.
Note: You must never use perlite in an aquaponics system as fish can breathe in the tiny particles and clog their gills. If you look closely at perlite, you’ll see it is a collection of little bubbles. So while it may not cut you, it’s coarse and will damage soft tissue, such as the gills of fish.
The most common way to use perlite is in propagating plants by cuttings. The improved drainage provokes faster root growth as they look for water and nutrients. Additionally, because the cuttings drain well, you eliminate the possibility of root rot. A rooting gel, like Clonox, can help further accelerate root growth.
Of course, you can also use perlite as a standalone growing medium, but it can be difficult to manage in a high-water system. Because of its light weight, perlite tends to float and you don’t want your growing medium floating away!
What is Vermiculite?
Vermiculite is an all-natural mineral product that increases nutrient retention levels and water retention.
In its natural state, vermiculite looks like mica. It is mined from various regions across the world and processed under immense heat until the structure is altered. The final product looks like small pellets composed of many layers.
Water retention in vermiculite is far superior to perlite, leading to more robust and healthier plants. However, it’s less aerating. Vermiculite is well-suited for plants that require damp soil that shouldn’t dry out. If you have a plant that requires a lot of water, mixing a scoop of vermiculite or using it alone is the correct path to go.
Be warned though: Since vermiculite absorbs up to 4 times its volume in water, your pot may be heavier than expected.
If your soil is of poor quality, adding half the soil’s weight in vermiculite (add it deep in the container) can quickly improve the quality.
Its water-holding capabilities make vermiculite a suitable anti-caking agent in dry fertilizers and pesticides while its high cation-exchange capacity helps it store nutrients for later use.
Note: A popular piece of misinformation is that vermiculite contains asbestos or that it’s a form of asbestos. This rumor originated when vermiculite out of a mine in Libby, Montana was found contaminated with asbestos. The mine was closed in 1990 and vermiculite from other mines has been proven to be harmless.
3 Benefits of Vermiculite
Excellent water retention
Vermiculite holds water extremely well and is the go-to option for water loving plants.
Doesn’t rot
Similar to perlite, vermiculite isn’t sourced from natural, raw materials and is processed under massive heat, eliminating the possibility of any bacteria or fungi. It doesn’t rot or mold and is completely sterile and non-toxic.
Lightweight
The light weight of vermiculite makes it perfect for plants with delicate root systems such as lettuce.
2 Best Vermiculite Brands To Buy
Black Gold Vermiculite
| Description | Black Gold is the retail arm of Sun Gro Horticulture, North America’s largest manufacturer of horticultural-grade peat. That should give you an idea of the quality you can expect. Black Gold Vermiculite can be used standalone or added to a custom mix. Since it’s light and easy to handle, it will easily mix with composted pine bark, peat, soil, fertilizers, pesticides, and other compost organic materials. |
| More Info | View on Amazon → |
Espoma Vermiculite
| Description | The Espoma Company has built up quite a reputation over the decades. Espoma vermiculite is ideal for organic gardening, hydroponics systems, or simply to improve aeration in heavy soil. It doesn’t create mold or root rot and holds up moisture very well. |
| More Info | View on Amazon → |
How To Use Vermiculite In Hydroponics
The high water retention of vermiculite can suffocate your plants if you aren’t careful. This is why it’s generally mixed with other media, most often perlite because the two complement each other quite well: Vermiculite retains water and perlite drains quickly. The general ratio is a 50/50 formula that ensures the mix isn’t washed away in ebb and flow systems.
This ratio may differ in hotter climates where a higher water-holding capacity may be desired.
Since vermiculate breaks down after some time, it’s a preferred medium for short-term plants like lettuce.
Perlite vs Vermiculite: Which Is Right For You?
Skimmed the article above? No problem! Here’s when to use perlite vs vermiculite.
Use perlite if:
- You live in a region with a humid climate. Perlite helps avoid water-logged growing media.
- You’re looking to loosen clay soil.
- Your plants need a dry growing medium.
Use vermiculite if:
- You’re repotting outdoor plants. Potted plants dry more quickly, and adding vermiculite helps retain moisture.
- You live in a dry region where your growing medium needs to conserve water.
- You’re starting seeds.
What do you think is best for your hydroponic garden? Let us know in the comments!