The natural material perlite comes in non-toxic forms and can be safely added to potting mixes if your plants need a medium that drains well. Perlite removes excess water from the soil while making it lighter and improving drainage. These little white spheres have multiple uses, including aerating soil, growing plants, and rooting stem cuttings. Perlite can hold moisture, making it useful for rooting and growing plants.
You may have questions about perlite even though it is widely used for houseplants and gardening. For example, is it safe to use in the home? Can it be used as a soil amendment in organic gardening? And what are the pros and cons of using perlite in potting mixes?
You’ll find all the answers to your questions about using perlite in soil for growing plants in this article.
What is Perlite?
It is a volcanic glass that usually appears black or dark gray in its natural form. Perlite is an amorphous mineral — meaning it doesn’t have a set structure. However, the perlite you buy at the garden center looks quite different from what you will find in the ground.
Often called Styrofoam balls, perlite is made of naturally-dense minerals. It’s extraordinarily lightweight, usually white, and is available in many varieties. What made this naturally-dense mineral into the lightweight soil ingredient that gardeners love so much?
Perlite is sometimes called volcanic popcorn since it’s often heated to 1,600°F (876°C) before being processed. The volcanic mineral is heated to the same temperature as popcorn, making it expand up to 16 times its original size. Horticultural perlite is extremely porous.
Because perlite is non-toxic, it increases humidity and has a neutral pH level; it also absorbs moisture on its outside. Since perlite is lightweight and does not change shape under pressure, it allows excess water to drain from potted plants and garden soil.
What is Perlite Made of?
Perlite is an ecologically significant mineral as well as a type of rock or glass. It is essentially formed when minerals that form as molten lava cool and store water. In order to produce white, lightweight perlite, volcanic rock or glass is heated up, causing the moisture in the mineral to expand. The dense mineral is then transformed into the lightweight, white mineral we call perlite.
This mineral is made up of silicon dioxide, the same component of quartz and sand. Perlite also contains aluminum oxide, sodium oxide, potassium oxide, iron oxide, magnesium oxide, and calcium oxide. It is also a high water content mineral, which accounts for its ability to pop.
Uses of Perlite
Perlite is primarily used to enhance soil quality, which in turn helps plants grow better. Perlite is also used to keep soil loose, increase aeration, and prevent compaction, as well as to grow plants hydroponically, create soilless mixes, and start cuttings.
In the case of houseplants, you can safely use perlite as a soil amendment. Select potting mix that is equal parts loam, peat moss, and perlite. This mix is perfect for growing indoor plants in containers because it holds the correct amount of oxygen and moisture.
Apart from its use in soil modification, perlite is also used to make insulation, cement, and drywall boards.
What Does Perlite Do for the Soil?
Growing plants indoors or outdoors can benefit greatly from the use of perlite, which is a soil amendment that is light, airy, and drains well. Perlite also eliminates problems such as root rot, fungal issues, and bacterial diseases.
The following soil problems can be addressed with perlite:
- The perlite loosens heavy clay soil, preventing water from pooling on the surface.
- The perlite in soil allows roots to receive adequate amounts of oxygen and nutrients.
- Perlite facilitates the growth of roots.
- A soil enriched with perlite will provide plant stress protection because it will insulate against temperature fluctuations.
- Perlite doesn’t deteriorate.
- Perlite is an ideal soil medium for potted plants, patio landscaping, window boxes, and ornamental containers.
How to Use Perlite in the Garden
A popular way to improve the soil quality in your backyard is to use perlite. If your garden soil is mostly clay, puddles may form, or too much moisture may stay in the ground. Perlite helps improve drainage, which allows plant roots to grow better.
Additionally, the perlite soil amendment allows beneficial insects to keep the soil healthy and fertile.
What Type of Perlite to Use in Your Garden?
The white Styrofoam. These balls are available in different grades: coarse perlite, medium perlite, and fine perlite, and you should pick the right type depending on how much you need to amend the soil in your garden or for containers.
Perlite comes in three different varieties, which you can buy at garden centers or in stores:
Coarse perlite. Perlite is the largest type of perlite available, and it works well for dense, heavy soils, as well as for soilless growing mediums like orchids or succulents.
Medium perlite. Plants in containers and pots are commonly grown in medium grade perlite.
Fine perlite. It’s important to use light-grade perlite when you’re starting cuttings or seeds. It is difficult for most stores to carry bags of this type of perlite.
How to Use Perlite in Hydroponics
Perlite is one of the best hydroponic solutions to use. Since it has a neutral pH level, won’t absorb nutrients, and is so inexpensive, people can use it to create hydroponic growing mediums. Just fill your containers with fine-grade or medium-grade perlite.
As perlite dries out more quickly than some other hydroponic mediums, you may want to combine it with others. For example, you may wish to use a 50-50 mix of perlite and vermiculite for hydroponic growing.
How To Use Perlite for Rooting Cuttings
The advantages of perlite for establishing cuttings are that it provides decent hydration and oxygenates roots without becoming soggy. Perlite is a terrific medium for growing plants that you need to root because it is light, permeable, and moisture-retaining.
Rooting stem cuttings in perlite is very straightforward. Here’s how you do it:
- Add moist perlite to a small pot.
- Compact the perlite granules slightly by gently pressing them down.
- Put a single plant cutting in the perlite medium.
- Place moist perlite in the remaining space in the pot, then gently press down on it to support the cutting.
- Place the pot in a bright, sunny spot.
- Perlite should be lightly misted regularly in order to avoid drying out. However, it should never become overly wet.
- Once the cuttings have rooted, transfer to a new, larger pot that contains the appropriate potting mix.
A Ziploc plastic bag can also be used to root cuttings with perlite. To root cuttings with this method, follow these steps:
- Make sure the Ziploc bag is one-third full of moist perlite.
- Your cuttings should be placed in the perlite, then the bag should be filled with air and sealed.
- Depending on the bag, try to keep it in a bright, but protected, place.
- Make sure the perlite remains moist in the rooting bag.
- Once your cuttings have rooted, transfer to a pot for growing.
Advantages of Perlite
Perlite has many advantages when it comes to growing houseplants or amending garden soil. The fact that it’s a natural, sterile substance means that organic and traditional gardeners can use it safely. What other reasons are there to use perlite soil mixtures? Here are five benefits of perlite:
Perlite is reusable
When you repot your houseplants, perlite keeps its form, so you can reuse it. You should discard the diseased soil with the perlite if you want to reuse it. Perlite does not break down in the soil like other soil amendment ingredients.
Perlite is neutral in pH
When the soil is added to perlite, the acidity or alkalinity of the soil is kept consistent. Perlite is a good choice if you need acidic soil or alkaline soil.
Perlite doesn’t absorb nutrients
Additionally, perlite does not deplete the soil of nutrients, like coco coir, rock wool, and pebbles, which can absorb nutrients. You can use perlite over and over by rinsing it before use.
Perlite is inexpensive
Low cost of perlite makes it attractive even to people with only a few houseplants. But if you have many indoor plants or want to improve the soil texture in your yard, high-quality perlite is an excellent option.
Perlite aerates soil and improves drainage
Perlite is often used in soil as a means of improving drainage, oxygenating the soil, and preventing compaction. It is very effective at helping prevent many growing problems.
Disadvantages of Perlite
It’s important to consider the ecological concerns when you use perlite in your home or yard.
Perlite is from a non-renewable source
Although there is plenty of perlite to go around, it is not renewable. Although there are adequate supplies, it is gone when it’s mined. Of course, the fact that perlite is reusable may offset this disadvantage.
Perlite dust could be hazardous
It is important to wear a protective mask and goggles when using perlite to pot houseplants or to modify garden soil. According to some, high-grade perlite is virtually dust-free. However, it is dangerous and should not be used for garden soil modification.
Not suitable for all plants
Generally, perlite is praised as one of the best soil amendment ingredients, but some plants do not thrive when perlite is added to the soil especially coarse perlite. For instance, plants with deep roots such as chives or mint may grow poorly with perlite.
Perlite vs. Vermiculite
Perlite and vermiculite are both natural products and used soil as additives to help aerate soil. However, there are differences between the two. Vermiculite tends to retain more moisture and is not the best choice for well-draining potting mixes. However, vermiculite may be better than perlite for plants that grow best in damp soil.
Perlite vs. Pumice
Both pumice and perlite are derived from molten lava. Both materials have porous properties that boost drainage in soil. For tall plants, gardeners recommend using pumice rather than perlite because it goes deeper. Perlite is cheaper than pumice.
Does Perlite Break Down?
The use of perlite in garden soil or houseplant soil will help retain essential moisture and aerate the soil or lawn until you remove it. Unlike other ingredients, such as bark, coco coir, or compost, perlite does not deteriorate in the soil.
Is Perlite Organic?
Since perlite is a natural product derived from volcanic ash, it is safe for organic gardening. Perlite is on the list of organic ingredients approved by the United States Department of Agriculture. It does not undergo any chemical processing.
Some people wonder whether perlite is organic or not because it is an inorganic material. However, this simply refers to the fact that perlite is not organic; it does not contain carbon, so it is referred to as inorganic matter.
Can You Grow Plants in Just Perlite?
If you want to grow plants without soil, perlite is a good choice. Perlite retains moisture and oxygen, which is essential for plant growth. Perlite floats in excess water, so a combination of perlite and peat moss may be the best choice.
Is Perlite Harmful?
Perlite is non-toxic and mostly made up of silica, which is also found in sand. When you use it for potted plants or repotting them, you can handle it safely. Perlite has many advantages for agriculture.
Research on the toxicity of perlite found no risk to the general population. However, perlite dust is considered “nuisance dust.” Therefore, it’s not advisable to breathe in perlite dust or ingest it. Always wear a face mask when handling perlite.