Guide for a DIY Soilless Seed Starting Mix (+ Recipe)

There are many benefits to using a soilless seed starting mix that is peat-free, easy, and budget-friendly. We use this DIY soilless seed starting mix recipe to grow our aeroponics garden’s seedlings. But it can also be used for hydroponics and growing in your garden soil.

Soilless Seed Starting Mix


  • soilless seed starting mixes are sterile, light, airy, and have water-retaining properties. All the necessary ingredients for the seed-rearing process.
  • our soilless seed starting mix recipe is peat-free, which is great news for the environment
  • soilless starting mix is easy to make with materials readily available at any good quality garden center.

Growing plants without soil have always tickled our gardening curiosities at the Garden Bench Top. It seems like such a foreign concept.

Like, how are you supposed to get your hands dirty (Garden Bench Top motto) without soil?!

But we are always open to new gardening ideas and concepts. Plus, it gives us a reason to explore new techniques – which always piques our interest.

Just want to Learn How to Create a Soilless Seed Starting Mix?

Jump to our step-by-step guide and recipe (without our waffling) HERE.

Benefits of Using a Soilless Seed Starting Mixture?

There are many reasons why soilless soil mixes are beneficial for gardening.

These include:

  • Light, airy, and well-draining – the materials we use in our soilless mix combine all the necessary properties a seed starting mixture requires. The perlite adds a lightness to the mixture, which allows the seedling to easily push through and make its way up out of the mix. Perlite is also porous, allowing plenty of airflows and excess water to drain.
  • Water-retention – vermiculite is the other material that contributes to the soilless mixture’s lightness. However, more importantly, vermiculite also retains water, vital for growing the seed and seedling.
  • Budget-friendly – both these materials are easy to source from local garden centers. But, if you can’t travel, you can also source perlite and vermiculite online from Amazon.
  • Neutral environment – using your own soilless seed starting mix allows you to control the pH levels and prevent disease or pests from attacking your seedlings. It also ensures there are no stray weed seeds that may be present in the soil. The recipe we use creates a neutral environment that seedlings require to thrive.
  • Good for the environment – all the materials we use are renewable resources and are carbon neutral. Unlike some materials, such as peat, which can release stored carbon when harvested from its natural environment.

Using Soilless Seed Starting Mix for Aeroponics

There are many reasons why you may want to use a soilless seed starting mix, such as hydroponics, or simply want to start your seeds in a sterile environment (disease and pest free).

The truth why we are trying our hand at soilless starting mixes is for selfish reasons. We recently purchased the Air Garden growing system for our first foray into aeroponics.

There are many types of aeroponic systems available, and they all operate on a similar concept of a tower where water is misted down a column with plants suspended along the column. Once we receive ours, we’ll post pictures. Here is a simple design detailing the process (although ours is a vertical structure).

How Aeroponics works

To say we are excited is an understatement.

credit: tenor

For those who haven’t heard about aeroponics, it is the growing technique where the plants are suspended in the air – hence the name aeroponics. It uses misted water to deliver moisture and nutrients to the plant’s root system, meaning it is soilless.

You may be asking yourself, isn’t that just hydroponics? The main difference is in hydroponics; the roots are immersed in the water versus being suspended in the air, as is the case for aeroponics.

How to Create a DIY Soilless Seed Starting Mix

Okay, that’s enough of the preamble; let’s create a DIY soilless seed starting mix.

Soilless Seed Starting Mix Recipe

For the recipe for our seed starting soilless mixes, we will be creating using a 1:1 ratio of:

  • perlite, and
  • vermiculite.

Note – you can also use other neutral organic materials, such as coconut coir which has a coarser texture. As long as it is light, airy, and can retain water.

Step-by-step Instructions Growing Seeds with a DIY Soilless Seed Starting Mix

1. Do Your Research

Before you get too far into the process, it is wise to ensure you have seeds suitable for aeroponic systems!

This step is simple enough but easily overlooked.

Search online or enquire with the manufacturer of your aeroponics system to help you identify if the plants you intend to grow are suitable.

Also, use your gardener’s intuition. Understanding simple things like root vegetables will not grow well in an aeroponics system. The container cups that hold each plant will restrict the growth.

2. Combine the Soilless Mediums and Fill Seeding Tray

Combine soilless seed starting Mix

In a separate container, combine the perlite and vermiculite in a 1:1 ratio. In other words, one cup full of perlite with one cup full of vermiculite.

Thoroughly mix the two until you end up with a consistent mix.

The perlite is excellent for keeping the soilless mixture light and airy.

While the vermiculite will retain the moisture necessary for germinating and sustaining the seedlings.

3. Plant Your Seeds

Plant seeds in soilless starting mix
Plant seeds in soilless starting mix

Plant the seeds into each seeding container cell according to the instructions on the seed packet.

As with usual seeding techniques, each seed has different requirements for the depth at which it should be planted.

If you do not have instructions, a general rule of thumb with planting seeds is to plant them at a depth of 2-3 times how wide they are.

A general guide for the depth to plant your seeds is at a depth that is 2 to 3 times their width.

4. Place Seeds in Humidity Chamber or Incubator

Place your newly planted seeds into a humidity chamber or incubator to help maintain the humidity levels around the seeding tray.

Water your seeds and ensure the soilless seed starting mix is thoroughly soaked. Discard excess water.

Soak your soilless seed starting mix

You can easily create your own incubators or humidity chambers. For example, you can use snap lock bags or even old, old clear plastic soft-drink bottles. Anything that allows us to reuse or upcycle is a positive.

For ideas on how to make your own DIY humidity chambers, check out our guide.

Moisture is a crucial element for seed germination and when sprouting seeds. The presence of moisture helps the seed’s outer layer break down and allows the germination process to begin.

Ensure you also allow air to circulate in and around the humidity chamber via vents or holes you have created.

The sprouting stage duration will depend on the type of seeds you are growing. And it can take anywhere between a couple of days to a couple of weeks.

5. Give Your Seedlings Light

Once the cotyledon or first seed leaves form, and you start to see the beginning of the first true leaves, move the seedlings under a grow light that is positioned 20-30 inches above the seeds.

You can place them on a well-lit window. However, we like to use grow lights to prevent seedlings from developing awkwardly, as they usually grow towards a light source.

6. Transplant the Seeds into the Aeroponics System

As we explained earlier, we will transplant the seedlings into an aeroponic system.

The best time to transplant is when the root ball has grown sufficiently and you can see stray roots protruding from the ball.

Ideally, the roots of the seedlings should be long enough to be exposed to the water mist running through the system.

This will ensure it grows strong and will receive the necessary nutrients to maintain its health.

And there you have it. You’ve just successfully raised plants from seed in your very own homemade seed starting mix without a single ounce of soil.



  • Cotyledon. (2022, December 13). In Wikipedia.