How to Use Perlite Vs Vermiculite In Soil - Backyard Boss
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How to Use Perlite Vs Vermiculite In Soil

Soil covers the Earth, but there’s more to it than meets the eye. Maintaining healthy soil involves continuous effort because various factors, including environmental and human activity, weaken its ability to replenish itself.

Many people use perlite and vermiculite to restore soil structure and mineral content for healthy plant growth and productive gardening. Read on to learn more about these amendments and how to apply them for optimal soil and plant health.

Why Amend Soil? 

soil
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Soil has many properties; for example, it can be well-draining, rich in nutrients, or not. How these properties interact with other materials can make or break soil’s texture and affect its health and productivity.

Unfortunately, soil can remain unproductive unless you rebuild its complex systems through restorative practices.

Adding amendments and conditioners helps improve the soil’s health and structure. Remember, you’ll need to test your soil and check its pH before amending it.

What Is Perlite

Close up, hand holding Perlite, potting cactus and succulent material.
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Perlite is a volcanic glass formed from viscous lava bearing a pale fine-grained composition. The amorphous glass contains 10 percent pitchstone, 2 to 5 percent water, and less than 1 percent obsidian.

Perlite comes from volcanic deposits that have been hydrated and cooled over time. People use heavy machinery to mine and extract perlite.

After extraction, machines crush the material into smaller fragments and send them off to a plant, where they are heated to create the finished product. When heated, the water content in perlite reacts, which causes it to “pop.” Following the pop, the perlite becomes 40 times less dense than before.

Perlite’s Role in Soil

Perlite in soil
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Although lauded for its utility in industrial settings, perlite is great for gardening. It can improve your soil in many ways. 

Overall, perlite improves moisture retention by enabling water to infiltrate deeper into the soil. Because it makes soil less dense, perlite reduces soil compaction, decreasing surface crusting and water pooling. 

Perlite conditions the soil and helps plant roots penetrate the soil more easily, improving air circulation and draining. Perlite is a neutral material that doesn’t affect soil composition or nutrient uptake. It’s sterile and can help insulate soil during temperature changes. 

How to Use Perlite

1. Cultivate Your Soil

woman wearing denim overalls and gardening
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For vegetable and fruit gardens, cultivate soil by hand or with a tilling tool to a depth of 6 to 12 inches.

2. Add Organic Matter

Peat Moss
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For vegetable and flower gardens, spread a layer of ½ perlite and ½ peat moss or compost and mix into the soil. Adding peat moss isn’t necessary if your soil is already rich in organic matter.

Mix ⅓ perlite, ⅓ peat moss, and ⅓ composted wood products such as bark or shavings for patio planters and other container plants.

3. Dig Deeper Holes

digging hole for planting
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When planting shrubs, trees, and ornamental plants, dig holes larger and deeper than the plant’s roots to allow them enough space to spread out and grow deeper into the soil.

Add perlite into the hole to cushion the plant’s roots and maintain moisture levels; this can prevent waterlogging and infection by fungal spores in the soil. After that, mix ⅓ perlite, ⅓ peat moss or compost, and ⅓ soil, and fill the hole with the mixture.

4. Use Perlite to Lighten the Soil

mixing perlite in soil
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Suppose you have limited garden space, a balcony, or a vertical garden. In that case, you’ll need to consider the weight of the planting mix. Planting mix can weigh anywhere between 120 and 140 pounds per 3 feet and could compromise your planting structures.

Fortunately, you can substitute a sandy, loamy planting mix with a soil mix of equal parts perlite and peat moss, which weighs around 25 pounds for every 3 feet when wet. You can use a perlite soil mix instead of a loamy one without significantly compromising soil quality.

What Is Vermiculite

vermiculite
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Vermiculite looks like mica but is a hydrated laminar mineral that is an aluminum-iron magnesium silicate. After mining the mineral, it is processed under intense heat, expanding into accordion-shaped granules with numerous layers of thin plates.

Vermiculite is commonly used in its expanded form because it is lightweight, absorbent, non-combustible, and an effective eco-friendly insulator.   

Vermiculite’s Role in Soil

vermiculite in the soil
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Horticultural vermiculite is an expanded form of vermiculite granules. It improves soil aeration and retains moisture and nutrients, which helps maximize plant health and growth.

Vermiculite is clean, odorless, sterile, non-toxic, and won’t rot in soil. In addition, it imparts cation exchange properties, which refers to how well soil can hold positively charged ions.

Vermiculite’s cation exchange properties mean it influences soil structure stability, nutrient availability and provides crucial minerals like magnesium and calcium to growing plants.

How to Use Vermiculite

1. General Potting Mix

Mixing soil with hand
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Rather than purchasing pre-made potting media, you can make a simple potting mix for general use that features this remarkable mineral. You will need:

  • 1 gallon of sterilized loam or garden soil
  • A basket
  • 1 gallon of peat moss
  • 1 gallon of vermiculite

Method:

  1. Pour the loam soil into a clean and sterilized basket to prevent insect infestation, infection, or diseases. This can prevent deformation or stunted growth in seedlings.
  2. Mix in 1 gallon of moist peat moss, then add the gallon of vermiculite.
  3. Check the potting mix texture; the ideal consistency is loose and well-draining. If it feels too granular, add more moist peat moss. If it’s too sticky, add more vermiculite and adjust until you are satisfied with the texture.

2. Adjustments

vermiculite
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Seed Germination

You can use vermiculite alone or mix half and half with soil or peat moss. If you use vermiculite alone, feed your seedlings with a weaker fertilizing solution (1 tablespoon for 1 gallon of water) when the first leaves appear.

Mulch

Use vermiculite as a year-round mulch and apply 2 to 3 inches of granules around shrubs, vines, and ornamental plants.

Transplanting

Dig a hole at least 6 inches deeper than a plant’s roots, then mix vermiculite with the topsoil. Place the mixture around the roots.

In Summary

Perlite and vermiculite are alike in their inorganic and sterile character, especially in their ability to amend the soil. However, while vermicular is more cushiony, perlite is harder and more porous.

Due to how their structures influence water absorption, they tend to serve different needs. For example, vermiculite absorbs more water in its layered structure however affords less soil aeration. Perlite, on the other hand, traps moisture in its smoother structure but releases it faster, creating more humidity around plants.

Selecting either granule will depend on the type of soil you desire or the plants you want to grow in your garden.

Hopefully, this article gave you some clarity when it comes to using perlite versus vermiculite in soil. Add your thoughts and questions in the comment section below and share the article if you liked it.

Happy Gardening!

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