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Is Perlite Safe For Organic Gardening?

If you are a certified organic farm, it’s important to know which chemicals and substances you are allowed to use when growing your crops. If you’re a small-scale home gardener who is trying to follow organic standards to raise crops you feel good about, it’s also important to be aware of what you can safely use in your garden.

Perlite

Perlite is allowed by the National Organic Standards Board, so it’s safe to use in organic gardening. Perlite is a naturally-occurring substance that is free of toxic chemicals and provides valuable benefits to plants.

The rest of this article will dig deeper into what perlite is, some benefits and drawbacks of this substance, and how to use it in your organic garden.

What Is Perlite?

If you buy a bag of potting soil from the store, you’ll notice little white balls that almost look like Styrofoam–that’s perlite. It’s a natural substance found in soil near volcanoes. In its natural state, perlite is a kind of volcanic glass. Over long periods of time, the volcanic obsidian glass is saturated by water, creating perlite. The process of turning this volcanic glass into a usable gardening substance is sometimes referred to as making “volcanic popcorn.”

The water in perlite pops when exposed to extreme heat, hence the nickname. To make gardening perlite, the glass is crushed and then baked to temperatures of 1,650 degrees Fahrenheit (900 degrees Celsius) to encourage the substance to expand.

Are There Different Kinds of Gardening Perlite?

Once the volcanic glass has been expanded into foam-like balls, it can then be separated into different categories based on size.

Super-Coarse Perlite

These perlite particles can be up to a third of an inch big, so they don’t mix well with most potting soils. However, they are fantastic at providing drainage due to the large pockets of air within them.

Coarse Perlite

This is the most common form of perlite used in organic gardening. It’s smaller than super-coarse perlite while still providing plenty of drainage, meaning it’s easier to use and can work with more soil types.

Medium Perlite

This perlite blends well with almost any soil, making it a great choice to add to smaller beds or potted plants.

Fine Perlite

This perlite can be difficult to locate in stores. It’s also not typically used to increase drainage since it’s so small. It’s more often used when starting seeds, as it can help encourage root production.

Why Should I Use Perlite in My Organic Garden?

Perlite can help with water drainage for your organic crops, but that’s not the only good thing about this organic substance.

  • Perlite is fairly cheap and is commonly carried at garden centers, meaning it’s not hard to find.
  • It’s sterile, so you won’t be introducing any diseases to your plants.
  • It can be reused since it doesn’t break down in soil, so you won’t have to keep buying more for the same beds year after year.
  • Perlite has a neutral pH (anywhere from 6.6 to 7.5), so it won’t make your soil more acidic or alkaline.
  • It has helpful natural minerals like calcium oxide, iron oxide, and potassium oxide that keep plants growing strong.
Espoma PR8 8-Quart Organic Perlite
  • Perlite
  • Helps loosen heavy soils and prevent compaction
  • Aerates soil and promotes root growth

Last update on 2022-05-15 / Affiliate links / Images from Amazon Product Advertising API

Are There Any Drawbacks to Using Perlite in My Garden?

Though perlite is a helpful substance to use in your organic gardening, it’s not without some flaws.

  • Perlite is a non-renewable resource. Since it’s a naturally-occurring substance found in soil from past volcanic activity, there isn’t an endless supply. Though it’s thought that it will take thousands of years to use up the perlite in the earth, it’s worth noting that it won’t be accessible forever.
  • Working with large amounts of perlite can cause problems with breathing and eyes. Perlite creates a dust that can be harmful in large quantities. If you’re using it in mass quantities, you need to wear safety gear to protect yourself. When you buy a bag at a garden center, adding a bit of water to the bag when you open it can help reduce the risk of danger.
  • If you buy the finer types of perlite, you will struggle with loss due to blowing winds. These smaller grades aren’t big large enough to stay put in soil when faced with strong, gusting winds.
  • Since it helps with drainage, perlite doesn’t retain water well at all. You’ll find that you need to water your plants more when using it.
  • Perlite can also be a victim to over watering. Because of how light and airy it is, it can easily float away in excess water.

How Can I Use Perlite in My Garden?

Though you can buy perlite in pre-mixed potting soil mixes, there are other ways to use perlite in your organic gardening process.

On the Surface of the Soil

One of the simplest ways to add perlite to your organic gardening routine is to sprinkle it on top of the soil. A fine-grade perlite will slowly work its way into the soil, helping with drainage and increasing aeration beneath the surface of the soil.

It’s important to keep in mind that fine perlite can blow away easily in the wind–and also be carried away by excess moisture–so be sure to sprinkle it on soil that is somewhat protected from the wind. Watering your garden in small amounts on a regular basis will help the perlite sink down into the soil without being carried away.

For Root Cuttings

As mentioned above, perlite can be a great growing medium to help produce strong, vibrant seedlings. Place your seeds directly into moistened perlite, then mist the perlite regularly to make sure it doesn’t dry out. An added benefit of seed-starting in perlite is that it’s easier to gently remove the plants to repot them without harming their roots than when using normal soil.

In Homemade Soil Mixes

Creating soil mixes at home is an easy process. By combining perlite with other components such as sand, compost, and loam, you can create the perfect soil to help your plants thrive. Be sure to use perlite as about 10-20% of your soil base, as using more will decrease the amount of nutrients offered to your plants.

In Hydroponic Gardening

Perlite can also be used as a hydroponic gardening growing medium. Since it’s so light, it should be combined with other growing mediums to prevent the perlite from floating away. Good options to add to your mixture are heavier mediums like pumice, coco coir, and vermiculite.

Mother Earth Perlite #3, Covers 4 cu. ft., Large and Coarse, Average Size 1/2 inch, For Hydroponic Use, Neutral pH
  • Mother Earth Perlite is an odorless growing media with a neutral pH of 7.0
  • Mother Earth Perlite #4 is one of the largest perlite on the market with a size of 1“ while Mother...
  • Adds porosity to soil and soilless mixes

Last update on 2022-05-15 / Affiliate links / Images from Amazon Product Advertising API

What’s the Difference Between Vermiculite and Perlite?

Vermiculite and perlite have may similarities, as they are both minerals extracted from rock. However, vermiculite retains more moisture than perlite does. This means that perlite is a better drainage aid, while vermiculite helps keep moisture in the soil.

Whether to use vermiculite or perlite depends on what soil your plants prefer. If they like damp soils, vermiculite is a good option. However, for plants that need well-draining soil, perlite is the way to go.

Is Perlite Safe for Animals?

Organic gardeners care not only about the health of humans who eat their food, but also about the health of animals who may forage near or inhabit their garden areas. Multiple studies have been conducted on the effects of perlite on animals. Though their findings varied somewhat, the overall consensus is that perlite doesn’t have a hugely negative impact on animals.

In the studies, animals were exposed to perlite dust at varying concentrations for a stretch of time. The majority of the studies found that the dust acted as a nuisance to the animals, but didn’t cause long-lasting or irreversible effects. Since animals in your organic garden are unlikely to be regularly subjected to massive amounts of perlite dust, the risk is even lower. Keeping your garden soil moist is an effective way to help keep down the levels of perlite dust in the atmosphere, thus keeping the animals safer.

Conclusion

Perlite is a natural substance that undergoes a small amount of processing before being used in gardens. It’s allowed for use in organic gardens by the National Organic Standards board, meaning it’s safe to use in organic gardens of all sizes. It’s also safe for use around animals.

This growing medium is disease-free, low-cost, and can be reused year after year. It’s easy to find in stores and can be mixed with other substances to create homemade soil mixes. However, perlite isn’t a renewable resource. Like fossil fuels, perlite will run out at some point. Working with large quantities of perlite requires protective gear, as the dust is harmful to respiratory systems. It can also blow away easily in a strong wind storm or be carried away by excess water on top of the soil. Despite its drawbacks, perlite can be a valuable asset to many organic gardening operations.

When used responsibly, perlite helps to grow strong, healthy plants and improves the soil. If you are growing organic crops for your family, producing food on a commercial scale, or growing houseplants, perlite may be a cost-effective, beneficial addition to your organic garden.  

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