Vermiculite vs Perlite: Which Should You Use In Your Garden?

If you are looking to enhance the way moisture is retained by soil and to boost its aeration, using either vermiculite and perlite is a great way to achieve this.

We will look today at what these treatments are and the key ways in which they differ.

The precise needs of the plants in your garden will dictate which of these works best. Take the time to think about the set-up of your outdoor space then determine which will be the most suitable fit for your requirements.

Contents

What Is Vermiculite?

Source: ArchiExpo

Vermiculite has been used for approaching a century across several industries. As well as horticulture and agriculture, the construction and industrial markets also make use of this fascinating mineral.

The name comes from the Latin vermiculare. This means “to breed worms” and it’s named in this fashion for the way in which exfoliation causes it to heat up and expand into pieces like a worm.

Vermiculite resembles mica in appearance.

This mineral has a very wide range of applications. Here are some of the many beneficial properties it boasts…

Sterile and inorganic
Low in alkalinity
Great ability to hold in water
Not toxic and presents no fire hazard
Fantastic air-holding capacity
Will absorb any excess nutrients
Non-irritant, non-abrasive
Does not deteriorate when stored in dry conditions
Strong insulating properties and lessens fluctuations soil temperature

Key Uses of Vermiculite

Potting Mixes

Vermiculite works wonders in potting compost. You will enjoy an open and very light compost by adding it to your mix.

Your compost will hold more water and rewetting is simplified. For you, this means that you will be able to hold out for longer between watering.

The ion-exchange properties of this mineral are first-rate. This causes any surplus nutrients to be efficiently absorbed. They will then be slowly released to the plants by way of the tiny root hairs.

Bedding Plants/Nursery Stock: Go for a 25/75 mix combining vermiculite with sphagnum moss peat
Greenhouse Pot Plants/Hanging Baskets: A 50/50 mix of the above works most effectively for these

If you already have your compost taken care of, you can still improve it. Simply add in 25% by volume of vermiculite and enjoy the many benefits this material will bring to your garden.

Seed Germination

Vermiculite is handy for germinating seeds. Its water-holding and aeration properties make it ideal for this purpose. It’s non-toxic and can safely come into direct contact with the seeds.

You can use it alone with no compost. If you do, feed your seedlings with a weak fertilizer solution as soon as they first appear.

With larger seeds, you can pop them in a small plastic bag along with some vermiculite. Close the bag at the neck. Keep it in a warm place until the seeds start to germinate. Once done, plant them in little trays of potting compost.

It’s also possible to apply vermiculite to the seed bed outdoors. This will reduce any danger of capping and enhance emergence.

Cuttings and Rootings

If you use the combination of vermiculite and sphagnum moss, you can enjoy stimulating the growth of plant roots. You’ll also benefit from a superior uptake of nutrients.

For cuttings under plastic covers or on a bench, shoot for a 50/50 mix.

25% is the recommended maximum if you use mist irrigation.

Make sure that you water the vermiculite well before you insert the cuttings. Also, avoid too much compressing at the base of the cutting.

What Is Perlite?

Source: National Gardening Association

Perlite is the generic name for a siliceous rock that occurs naturally.

It’s different from other volcanic glasses as when it is heated it will expand significantly.

Much like vermiculite, perlite has a diverse range of benefits…

Sterile, inorganic and inert
Stops any compaction
Better drainage and aeration
Not toxic and presents no fire hazard
Holds in moisture but does not get soggy
pH is nearly neutral
Helps roots to start effectively and grow well
Does not decompose and lasts for years

Key Uses of Perlite

Potting Compost

You can use perlite as a partial or complete replacement for sand and grit in your compost. You will notice a distinct improvement in insulation, drainage and aeration. Rewetting will also be boosted.

You can also open up the composts you have in place.

Soil-less Composts: Shoot for for an 80/20 mix of sphagnum moss peat and perlite
Loam-based compost: Equal parts perlite, sterilized loam and peat. Chuck in some nutrients and limestone for good measure

Make certain to mix it up nicely then water well.

Soil Conditioning

If you have clay or heavy silt soil in your garden, harnessing perlite will give you a superior texture. You will get better drainage and improved aeration.

With any problematic seed or flower beds, add around 25% perlite before sowing takes place.

For roses, shrubs and trees, mix up some perlite with your soil when you are filling your planting hole. This will help to encourage root growth. Firm it up around the roots then give it a thorough watering.

Dressing Your Turf

For any poorly drained or compacted areas of turf, perlite is a smart way to get more drainage and more air circulating.

You should notice a better balance of air and moisture. The turf will grow more efficiently. Roots will develop better.

In general, your turf will become more resilient as well as more tolerant of extremes of weather if perlite is introduced.

Spike the area you want to work with. Mix up some perlite with a fertilizer. Spread an extremely thin layer all over. Rake, brush, water.

A little goes a long way. A 100 liter bag should be good for an area of 50 meters square.

Differences Between Vermiculite and Perlite

While both vermiculite and perlite excel at helping with the way in which moisture is retained in soil then aerated, they are not always used in precisely the same way. They are actually different in terms of the way they are made up and the effects they deliver.

What, then, are the differences between these two materials?

Make-Up

Vermiculite is a silicate of aluminum-iron-magnesium silicate. The particles expand when it is heated. This promotes water retention. It can actually take in up to four times its own volume of water. Potassium, calcium and magnesium are also drawn in to the plants.

Perlite, on the other hand, is a silicon-rich volcanic rock. The tiny bubbles do hold in moisture just like with vermiculite. The difference is that perlite also draws in the air.

Retaining Water

Both these materials are superb when it comes to water retention.

Vermiculite is like a sponge and will take in even more than perlite. It will not aerate the roots as well, though.

Perlite is porous so drains better. Soil aeration is its real strong suit.

How Do They Look?

Vermiculite is a brown and spongy material. It comes in the form of flakes.

Perlite is white and granular. It resembles small foam balls.

Uses In The Garden

The principal ways in which vermiculite and perlite are used are for:

Aeration
Moisture retention
Soil compaction
Propagating plants
Cultivating seeds
Composting
Indoor growing
Lawn care

That’s quite a broad range of applications!

Its the different way in which they hold in water that makes them suited to various plants.

Vermiculite: Superb for plants that demand lots of water
Perlite: Far better for plants that don’t call for too much hydration like cacti, for example

Wrap-Up

We hope you have found this dissection of vermiculite and perlite useful.

Although some people believe the two to be interchangeable, the above comparison shows that this is not strictly true.

As with all aspects of gardening, pay close attention to the precise demands of your garden. There is no one-size solution.

If you have any questions regarding these two wonderful materials or any other aspect of gardening, don’t hesitate to contact us. We will get back to you as promptly as possible.