Vermiculite and perlite

Growing essentials

Some products are essential to growing Chillies successfully. These include additives, fertilisers, growth mediums, and certain chemicals. Particularly when growing in pots – the way I do. These products help me keep pests at bay, promote growth, facilitate water retention, drainage and achieve other objectives. They all have their place in what it takes to grow healthy productive plants. In this post, I will cover two of these essentials. Further posts will cover the rest

In my opinion, definite must haves for Chilli growing are vermiculite and perlite. These two products are used for different reasons.  Vermiculite is used as a growth medium and also as a means of retaining water in potting and seed starting mixes. Perlite, on the other hand, is used to aid drainage. Chillies don’t like their growth mediums to be too wet. So while on one hand you want your seed potting mixes to retain water, on the other hand you don’t want them to be sodden.  It is a delicate balance. Using perlite and vermiculite correctly will help achieve what you need to do

Some growers mix perlite and vermiculite into their seed, starting and potting mixes. How much to add depends on what needs to be achieved.  Perlite for example can be combined at one part perlite to one part vermiculite and added to one part coco coir for a seed starting mix.  For an enhanced seed starting mix, one part or vermiculite is combined with one part perlite. This is then  added to four parts coco coir and two parts garden compost


For water retention

Vermiculite gets its name from the word vermicular, which means to have the form of a worm.  When “ite “is added to a word, it implies it is a mineral or a rock. And that’s what vermiculite is. It is a naturally occurring mineral (magnesium-aluminium-iron silicate). It is mined in various countries around the world for its use in gardening, the building industry, the automotive industry and packaging.

The reference to worms refers to the fact that when vermiculite is heated to high temperatures, it expands into strands that resemble worms. It is heated after being mined to achieve its desirable properties.  For it to be used in horticultural applications, the stands are broken into fine brown granules. It then bagged. It is this format that you buy it from online, in garden centres etc

From a Chilli growing perspective, the desirable properties of vermiculite are that it is light weight, absorbs three to four times its weight in water, and attracts nutrients like potassium, magnesium and calcium when mixed with seed starting or potting mixes.

Some growers use vermiculite in its pure form to start seeds. These growers don’t mix it in a ratio of 1:1 with seed starting mixes, as other growers might do. They simply add the vermiculite, as it is in a layer a couple of inches in a seed tray. The seeds are sown on top of the vermiculite layer. Then the seeds and the vermiculite then get moistened using a spray bottle. Another layer of vermiculite a quarter of an inch think is then added on top of the first layer. This too gets moistened. And that’s it. The seed tray is now placed in a propagator. From there, it is a matter of waiting for the seeds to germinate. Similarly, the same process can be followed when the vermiculite is added to a seed starting mix

While I use worm castings in favour of vermiculite in my seed starting mix, it doesn’t mean I don’t use it all for seed starting. I typically plant the seeds in my seed starting mix, but will then cover the mix with a thin layer of vermiculite to discourage fungus gnats. Fungus gnats lay their eggs in most soil. By adding a layer of vermiculite, you can create a barrier that will make it more difficult for gnats to lay their eggs. Over and above, this vermiculite has anti-fungal properties and can help prevent diseases like damping off


For drainage

Perlite is a white, lightweight granule of expanded volcanic glass.  It is made by heating hydrated Obsidian to over 1000 degrees Celsius until it expands to many times its original size. It then shatters into the light weigh granules used in horticulture. It is then bagged, which is the way we will buy it from garden centres online.

Perlite like vermiculite can retain water, but its main usage in growing Chillies is to aid drainage. Adding Perlite to a potting mix aerates the mix, which allows water to pass through it.  This means the mix can remain moist, rather than become sodden. Chillies prefer moist, rather than wet growing mediums, so the ability of Perlite to aid drainage is greatly appreciated by Chilli growers.

Other mediums like sharp sand can have the same result, but as an all-round product for Chilli growing, Perlite must take top spot. The only use for horticultural sharp sand is for drainage, whereas Perlite can be used for other things

Perlite can be found in various grades. These include fine medium and coarse, and super coarse grade. Each grade is used for different purposes. The super coarse grade, for example, can be used for seed starting and propagation. The other grades, except for the fine grade, can be used in potting in mixes for Chiil growing to aid drainage

I use medium grade perlite to make up my potting mix. I add one trowel of perlite to four trowels of Coir soil and twelve trowels of a good all-purpose garden compost. I find this mixture works well for potting- on of the plants right up to hardening off. After hardening off, I continue to use the same mix, apart from a change of fertilisers


I always have a bag of these two products on hand for growing Chillies, but also many other things that I use. In addition to the neem oil and Castille soap I use for keeping aphids at bay. I have also have Epsom salts, hydrogen peroxide, garden lime, magnesium sulphate, organic bug sprays, worm castings, seaweed extract and various fertilizers that I use to grow my Chillies. I will discuss how I use these products in an upcoming post.






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