What Is Perlite: Learn About Perlite Potting Soil


Okay, so you bought the potting soil and have just planted a magnificent Ficus tree. Upon close inspection, you notice what appear to be tiny Styrofoam balls in the potting medium. Having heard of perlite, you may wonder if the little balls are perlite and, if so, what is perlite and/or the uses of perlite potting soil?

Perlite Soil Info

Appearing as tiny, roundish white specks amid the other components, perlite in potting soil is a non-organic additive used to aerate the media. Vermiculite is also a soil additive utilized for aeration (though less so than perlite), but the two are not always interchangeable, although as rooting mediums, both provide the same benefit.

What is Perlite?

Perlite is a volcanic glass that is heated to 1,600 degrees F. (871 C.) whereupon it pops much like popcorn and expands to 13 times its former size, resulting in an incredibly lightweight material. In fact, the end product weighs only 5 to 8 pounds per cubic foot (2 k. per 28 l.). The super heated perlite is comprised of tiny air compartments. Under a microscope, perlite is revealed as being covered with many tiny cells that absorb moisture on the exterior of the particle, not inside, which makes it particularly useful in facilitating moisture to plant roots.

While both perlite and vermiculite aid in water retention, perlite is the more porous and tends to allow water to drain much more readily than vermiculite. As such, it is a more suitable addition to soils utilized with plants that do not require very moist media, such as cactus soils, or for plants which generally thrive in well-draining soil. You may still use a conventional potting soil that contains perlite; however, you may need to monitor watering more frequently than those made up of vermiculite.

When growing plants in perlite, be aware that it may cause fluoride burn, which appears as brown tips on houseplants. It also needs to be moistened prior to use to reduce dust. Due to perlite’s large surface area, it is a good choice for plants that require levels of high humidity. Evaporation off its surface area creates higher humidity levels than those of vermiculite.

Uses of Perlite

Perlite is used in soil mixes (including soilless mediums) to improve aeration and modify the soil substructure, keeping it loose, well-draining and defying compaction. A premium mix of one part loam, one part peat moss, and one part perlite is optimum for container growing, enabling the pot to hold just enough water and oxygen.

Perlite is also great for rooting cuttings and fosters much stronger root formation than those grown in water alone. Take your cuttings and place them in a Ziploc bag of moistened perlite, about one-third full of perlite. Put the cut ends of the cuttings up to the node into the perlite and then fill the bag with air and seal it. Put the air-filled bag in indirect sunlight and check it after two or three weeks for root formation. The cuttings can be planted when the roots are ½ to 1 inch (1-3 cm.) long.

Other uses of perlite include masonry construction, cement and gypsum plasters, and loose fill insulation. Perlite is also used in pharmaceuticals and municipal swimming pool water filtration as well as an abrasive in polishes, cleansers and soaps.


Vermiculite Vs. Perlite

Related Articles

Perlite and vermiculite are both used to improve moisture retention and aeration in soil. They are used in a similar manner, but they are not interchangeable. Perlite and vermiculite are quite different in composition and in how they improve your soil. Determining which is better for use in your garden depends on your plants and their needs.


Daylilies forum→Perlite and seedlings

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Can I use perlite on the surface of the soil to help combat damping off? Not sure how to remedy the problem for my poor seedlings.

Any input is appreciated, thank you!

Name: Fred Manning
Lillian Alabama



Excessive water is one major factor that contributes to damping off. Bottom watering could help, and letting the media surface get dry between waterings. You can't do much about the medium at this point but I wonder if it is too dense? The temperature needs to be optimum for the seedlings so that they grow to get past the damping off stage more quickly, avoid temp extremes. A small fan blowing gently on the seedlings is another thing that may help as it increases air circulation and dries up the media surface. Don't mist the seedlings, and don't keep them covered with a dome or anything like that once the first one is up. What else. oh, try not to give them too much fertilizer as well. You probably don't need to fertilize new daylily seedlings for their first month or so.

You may already be doing much or all of this but just tossing out the things that help since I don't know how you're currently managing them.

sooby said: I've never heard of perlite having antifungal properties, I assume if it would do anything it would be to keep the media surface drier (same idea as sand). If you have a bad case of damping off you may want to use a fungicide. There are all kinds of "home remedies" also such as cinnamon and chamomile tea but I've never looked into them as far as effectiveness is concerned as I've managed to avoid getting damping off in seedlings in the first place by other measures.

Excessive water is one major factor that contributes to damping off. Bottom watering could help, and letting the media surface get dry between waterings. You can't do much about the medium at this point but I wonder if it is too dense? The temperature needs to be optimum for the seedlings so that they grow to get past the damping off stage more quickly, avoid temp extremes. A small fan blowing gently on the seedlings is another thing that may help as it increases air circulation and dries up the media surface. Don't mist the seedlings, and don't keep them covered with a dome or anything like that once the first one is up. What else. oh, try not to give them too much fertilizer as well. You probably don't need to fertilize new daylily seedlings for their first month or so.

You may already be doing much or all of this but just tossing out the things that help since I don't know how you're currently managing them.

Lots of great info in a nut-shell.



Perlite isn't antiseptic, but it's theoretically sterile, and you could always sprout your seeds in pure perlite, but you'd also need to transplant them when they're a couple of inches tall.

Try a 50-50 perlite/coir mix, also try a taller container, which will keep the top layer of mix well out of the standing water table that is in every pot.

Dampen the mix, tamp it lightly to level the surface, sow the seeds 1/4-3/8" deep, then water once after sowing with a fine spray/mist nozzle. You shouldn't have to water again until they sprout, if they've been stratified adequately.

Or you could fill the bottom of the container with your 50-50 mix, and use pure perlite for the top inch. Perlite isn't that good of a growing medium on its own, (poor ion-exchange) so having some real mix below will let the roots quickly find a better growing environment. Since pure coir has no available nutrients, you'll need to feed with a complete fertilizer as well as a calcium-magnesium supplement when they're an inch tall or so.


Using Perlite In Your Garden

As mentioned earlier, perlite offers a lot of benefits to your garden.

The most important one is drainage . Perlite is a natural filtration system, allowing excess water to easily drain away while retaining a little moisture and catching nutrients that plants need to grow. This is especially true in raised beds and container gardens, but also in the ground as well.

Airflow in the soil is greatly improved in a bed amended with perlite , and that’s necessary both for your plant’s roots to breathe and for any worms, beneficial nematodes, and other good natural garden inhabitants. Because it’s a mineral glass and thus harder than the soil around it, it also helps to slow down compaction, and keeps your soil fluffy and lightweight.

What Type of Perlite to Use

People often ask whether you should use coarse perlite as opposed to medium or fine-grade. Coarse perlite has the highest air porosity, so it offers the most drainage capability and ensures the roots of your plants can breathe well. It’s popular among people who grow orchids and succulents, and also people who do a lot of container gardening, as it provides excellent drainage, but the coarser bits don’t work their way to the surface of the soil blend as much as fine perlite does. Larger perlite is also less prone to being caught by a breeze and blown away!

The finer stuff is useful as well, but it’s used for starting seeds or rooting cuttings as the drainage provided encourages rapid root production. Fine perlite can also be lightly scattered across your lawn’s surface, where over time it’ll work down into the soil and improve drainage.

If you’re making your own potting soil , perlite is one of the most used components in the industry for the above reasons. It’s cheap, lightweight, and easy to blend into peat or other water-retaining ingredients! But there’s other additives like diatomaceous earth and vermiculite. Why shouldn’t you use those instead?

Again, it comes back to drainage. Diatomaceous earth, or DE as it’s also referred to, is more moisture-retentive than perlite is. It’s usually available as a powder rather than a granule, so it doesn’t reduce soil compaction in the same way, and it tends to clump when wet, which doesn’t allow as good airflow. There are many other uses for diatomaceous earth in the garden including pest control, and you can use it in conjunction with your perlite, but not to replace it.

When comparing perlite vs. vermiculite , vermiculite is very moisture retentive. It’ll absorb water and nutrients and keep them in the soil, which makes it perfect for seed starting blends or for plants that prefer lots of water. In conjunction with perlite, the vermiculite will absorb water and nutrients to feed your plants, while the perlite will help drain the excess water away. So both have their own place in your garden, even in the same container or bed, but they’re not interchangeable.


How to Use:

Perlite is very easy to use and is usually sold in bags.

When using perlite for gardening, it is very important to rinse it before use. Though everyone is different, the dust at the bottom of the bag may irritate some people’s throats when it is dry, so a mask may be worn to prevent inhalation. Note that this only occurs when the media is very dry this will only happen when it comes directly out of the bag. After it is rinsed there will be no problem.

Pour the perlite into a clean wheelbarrow or bucket and cover the aggregate with good quality water. Allow the perlite to sit in the water for at least fifteen minutes, which is enough time for any excess particles to settle. Usually the bottom of the bucket will be coated in perlite dust after it soaks in water for a period of time. Simply scoop perlite from the top, drain, and then it is ready for use! Combine with coconut coir, in roughly a 50-50 ratio for an ideal hydroponic media. Mix with potting soil and use for planting potted or garden plants. Perlite may be used alone or combined with other media to grow all kinds of plants.

Vermiculite is similar to perlite, in that it is a mineral that is mined and heated to very high temperatures so that it expands. It is used for its water-holding capacity, but it can become waterlogged. History: The term vermiculite dates back to 1824 and comes from the Latin word, vermiculare, which READ MORE Growing Mediums Related Article

Coconut coir is a widely available growing medium that is becoming quite popular. Coconut coir is made from the husk of the coconut, which is often considered a byproduct when coconut is used in other industries. Coconut husk is processed to produce fibrous material for use as a growing medium, READ MORE Growing Mediums Related Article

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Vermiculite is non-organic soil and is similar in certain ways to perlite, but there are some distinct differences. Both are lightweight, water retentive, non-toxic, and fireproof, making them alike in that sense, but industries utilize them differently. One major difference lies in the fact that perlite originates from volcanic glass, whereas vermiculite contains mica, a sheet silicate mineral. Companies heavily mine both substances. Vermiculite mines exist in South Africa, China, Russia, and Brazil. Like perlite, vermiculite also has many industrial applications.

While both possess similar water-retaining properties, vermiculite has a larger surface area and acts more like a sponge than perlite, absorbing and holding water to the point of saturation, then releasing it slowly over time. It also creates a soil environment that retains water. If you are growing a cactus or other plants that have low water needs, vermiculite is not the correct amendment for those types of plants. You will need a medium that offers quicker draining, such as sandy soil, coco coir, or a mix of different materials. Your best bet is to get some perlite in this instance.

Switch plant types, however, and things change. If you were growing mushrooms, for example, vermiculite would be an excellent choice for an additive to the substrate, the surface from which they grow, because of its moisture retentive properties. Vermiculite is also effective at aerating or expanding the soil.


Watch the video: ORCHIDS. Re-potting my small standard in soil ProMix BX + perlite. The root grew into the bark.


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