Vermiculite and Perlite Aren't Interchangeable—Here's How to Use Each One

Every gardener wants nutrient-rich soil. But just because your yard doesn’t have enough nutrients naturally doesn’t mean you can’t add more with the help of vermiculite or perlite, common soil additives. Both are generally neutral in their pH balance and are non-toxic. Depending on your garden’s soil type and plants, one could be a better solution to your soil concerns than the other. We spoke with gardening experts to learn the differences between vermiculite and perlite—and how to use each to boost your soil quality.

Perlite vs. Vermiculite

Perlite
Perlite is a lightweight, granular material made from ground volcanic rock that is usually white in color. It is used to aerate compost and improve soil drainage and aeration. Gardeners typically add this to soil that holds too much moisture.

Vermiculite
Vermiculite is a naturally occurring silicate mineral that is used to retain moisture in fast-draining soil. When heated, the material used to make vermiculite expands into an accordion shape to hold air, water, and nutrients, according to Jeremy Yamaguchi, CEO of Lawn Love.

How to Use Perlite When Planting 

If your garden’s soil drainage needs to be improved, perlite can help. “For example, heavy clay soils retain water for a long time, so perlite is often used to help improve drainage,” Yamaguchi explains. Perlite is also used when potting plants that thrive in dry or well-aerated soil, such as succulents and rhododendrons. “It prevents water from pooling around the roots, reducing the risk of root rot,” says Karen Mcclure, director and lead designer of Karen Mcclure Garden Design. 

How to Use Vermiculite When Planting 

Unlike perlite, vermiculite is a great option for helping soil retain water. “Vermiculite can help improve the holding capacity of sandy soil, so it can retain water and nutrients long enough for plant roots to absorb them,” says Yamaguchi. Its moisture-retention qualities make vermiculite very useful for seed starting, as seeds need consistent moisture as they work to get established. “When mixed with seed-sowing compost, vermiculite helps retain moisture and promotes seedling development," Mcclure says. 

Pros and Cons of Perlite

Perlite has many advantages. It improves your soil’s drainage by helping prevent water from accumulating, which can prevent root rot. It also enhances soil aeration by keeping your garden’s soil light, thus preventing soil compaction and promoting healthy root growth. Perlite does all this while being cost-effective and is generally more affordable than vermiculite.

However, perlite does have a few disadvantages. “It is not suitable for plants that require consistently moist soil, as it does not retain water as effectively as vermiculite,” says Mcclure. Perlite also doesn’t distribute very easily in soil. “It can sometimes settle at the top of the soil, making it less effective than you’d hope for,” says Yamaguchi. You will want to mix this soil additive very thoroughly if using it.

Pros and Cons of Vermiculite

Vermiculite has numerous benefits. “It absorbs and holds more moisture than perlite, keeping the soil damp for longer periods,” says Mcclure, adding that vermiculite can also improve soil structure. This soil amendment is ideal for moisture-loving plants, like moss and ferns.

Vermiculite comes with a few drawbacks. Because it helps soil retain more moisture, it may lead to overly wet conditions and root rot for drought-tolerant species. “It should not be used for houseplants that require well-draining soil, such as cacti or succulents, as it can lead to excessive moisture retention,” Mcclure explains.