Perlite vs. Vermiculite for Potted Plants

Kick your green thumb up a notch and incorporate additives into soil to help your plants thrive. Vermiculite and perlite are both popular options, but even though they have similar properties, they have different uses. Certain plants prefer different soil amendments and could benefit more from one than the other. This guide will compare vermiculite vs. perlite and help you to choose the best option for your garden or houseplants.

What Is the Difference Between Perlite and Vermiculite?

Perlite and vermiculite both retain water, but each works differently for your plants. Perlite soaks up water and helps to improve drainage in a pot, while vermiculite acts like a sponge and helps soil to retain water. Perlite is best for plants that need to dry out between waterings, and vermiculite is best for plants that need constant moisture.

What Is Perlite?

Perlite is a naturally occurring mineral found in volcanic glass that, in its natural state, has a pearl-like sheen. Like vermiculite, once treated, perlite is an amendment that is used to enhance soil quality, creating a rich environment to improve plant growth.

During the manufacturing process, perlite is heated until it expands and pops, turning into white porous pieces that are seen in many types of potting mixes. After the heating process, the perlite is larger and lighter than its original weight, ranging in size from coarse to medium to fine. Perlite does retain moisture and holds four times its volume in water, but it is less absorbent than vermiculite, which holds sixteen times its volume in water. 

Perlite is better suited for plants that require a dry environment, like succulents, cacti, or orchids, as it dries out too quickly for water-loving plants. Similar to vermiculite, you can use perlite for starting seed mixes and creating custom potting soil mixes. Furthermore, you do not have to worry about introducing pathogens or pests to your soil because it is sterilized under high temperatures during manufacturing.

Best for:

• Orchids

• Cacti

• Succulents

Perlite Pros

• Inexpensive and readily available

• Does not rot or mold

• Does not absorb or take away nutrients from the soil

• Odorless, nontoxic, sterile

• Neutral pH level (if unsure of your soil’s pH level, check out our Soil Testing Cost Guide to learn more)

• Can be used on its own or mixed with other amendments to create a custom soil mix

• Can loosen compact and heavy soil

• Can loosen clay soil and prevent water from pooling on the surface of the pot

Perlite Cons

• Can settle at the top of the pot and not distribute as evenly as vermiculite

• Dust can be emitted, causing irritation

• Nonrenewable resource

• Porous, so it can capture solid debris or algae, causing blockage in certain plants

What Is Vermiculite?

Vermiculite is a mineral that, once treated, can be used as a soil amendment or be added directly to garden beds to improve soil quality and help plants grow. In its natural state, vermiculite takes the form of glossy flakes, but once heated and sterilized, it expands to long brown or beige worm-like strands. There are different sizes of vermiculite, which is how different grades (from micro up to coarse) are created. After expanding, the vermiculite particles become spongy and porous, which improves soil aeration and increases its water retention capacity. 

Gardeners use this type of amendment to generate healthy soil for their plants. Vermiculite lightens heavy soil, which creates a more desirable environment for plant roots. Its unique shape enhances the quality and structure of the soil by holding water, allowing the plant to tap into it as needed. Unlike more natural soil amendments, there is no risk of introducing pathogens or parasites to the plant because of the rigorous sterilization process that vermiculite goes through.

Vermiculite is best used for water-loving plants, such as ferns, spider plants, and even certain herbs, like basil or parsley. It is extremely absorbent, acting as a sponge by holding water for a plant’s roots to access. You can also use vermiculite for starting seeds or storing bulbs between seasons.

Note that the vermiculite used for potting plants does not contain asbestos and never has. In the past, vermiculite used to create insulation often came from a mine contaminated with asbestos, causing the confusion.

Best for:

• Moisture-loving plants

• Rooting plant cuttings

• Starting seedlings

• Storing bulbs over the winter

Vermiculite Pros

• Mixes well with soil

• Will not rot or mold

• Extremely absorbent

• Can be used individually or in a soil mixture

• Versatile, attracting plant nutrients like potassium, magnesium, and calcium

• Helps roots grow

• Prevents seeds from drying out during germination

• Lightens heavy soil

Vermiculite Cons

• Can hold too much water for certain plants, potentially causing root rot due to excess water

• Nonrenewable resource

• More expensive than other soil amendments

• Harder to find in garden centers and home improvement stores

Vermiculite vs. Perlite: Key Characteristics Compared

Vermiculite and perlite both work to improve soil quality, but individually, they work better for specific scenarios. Keep in mind that both are sterile, odorless, and free from insects and parasites. Neither will rot or decompose.

It is important to note that vermiculite and perlite can be used to complement each other when creating a mix for potted plants. This can help certain plants grow by using perlite to aerate the soil and allow oxygen to reach the roots, and using vermiculite to keep the moisture in. The main difference is that vermiculite holds more water than perlite, but perlite is better for drainage. Here are some different factors to keep in mind when choosing a soil amendment for your plants.

Longevity: Vermiculite

Even though both vermiculite and perlite do not deteriorate or decompress, vermiculite is considered a more permanent option than perlite. Vermiculite evenly distributes throughout the soil, whereas perlite can float to the top. Plus, perlite risks being washed away due to its lightness and buoyancy when used on its own.

Availability: Perlite

Perlite is more widely available, whereas vermiculite can be challenging to find in garden centers or home improvement stores. Perlite is also a cheaper option than vermiculite, in most cases.

Water Retention: Vermiculite

As previously mentioned, moisture retention is one of the fundamental properties of vermiculite. The water-holding capacity is an ideal additive for plants that thrive in moist soil conditions. Let the vermiculite retain moisture to keep your water-loving plants thriving. 

Air Retention: Perlite

Perlite particles are full of nooks and crannies, which helps to aerate soil, breaking it up and improving the flow of air throughout. It is ideal for use with soil that compacts easily and with plants that need plenty of air flow.

Drainage: Perlite

Perlite is an ideal growing medium for plants that prefer dry conditions and require ample drainage. It acts as an aerator, helps the soil to shed excess water, and can improve drainage in both soil-less and soil-based potting mixes.