Home > Blog > Current Page

How Potting Mixes Work – How to Make Your Own Potting Mix

Table of Contents

In this post I will provide you with a step by step process to make potting mix for all of your houseplants. The instructions are at the bottom of the page, along with the supplies I recommend. Here are the main supplies you will need:

Why is it important to understand potting mediums?

When we spend as much money and time on our plants as we do, it is crucial that we know how to care for them. For the first few years of owning houseplants, I bought the basic Miracle-Gro houseplant potting mix which worked just fine. I can understand the resistance to learn about substrates and potting mixes when the local gardening store has three aisles of pre-mixed substrates and soils that all seem to do the trick. However, there is more to the story than that. I do want to make it clear that I don’t think you should feel guilty for using those. There are circumstances in which pre-mixed media is the best option; I even keep a few bags of it myself!

houseplant being repotted with new potting mix or soil
Photo by cottonbro on Pexels.com

Really, I want to help you understand what is in them and encourage you to make informed choices. Most of those mixes will work for you and your plant babies. But there will be a point when you use your normal potting mix on your brand new Sansevieria and the high-nitrogen fertilizer that it contains inevitably burns and kills it.

By the end of this post, you should be able to understand what potting mediums are made of, what chemicals and additives are included, when it is useful to mix your own soil, and how exactly to do so. I am going to include instructions on how I mix my potting mediums and what products I find work best. If you follow these instructions, you will find that every plant on our plant search has a section called “supplies we recommend”. In this section, I will list the adjustments that I recommend based on the instructions I provide in this post, along with other recommendations for things your plant may need.

I would also like to mention that I am not in any way a scientist or expert. I have learned what I know from my own research and experiences. Some of that research is collected from scientific articles, some from speaking with growers and collectors. This is mainly just my opinion!

green leaved plants
Photo by Huy Phan on Pexels.com

Is it okay to use premixed soil for my houseplants?

Well, it really depends on the kind and brand. Most potting mixes are broken up by perceived “groups of plants”, such as “Houseplant”, “Succulent”, “Flower”, or “Vegetable”. The issue with this is that these terms are sort of meaningless, or at least not completely accurate when it comes to the actual needs of each plant. For instance, a “houseplant” could be an Anthurium or an Alocasia. Anthuriums thrive on an “orchid” mix, while Alocasias prefer the “houseplant” mix. I’m sure you’ve also seen this issue with fertilizers; I actually use a “vegetable” fertilizer for many of my plants.

Just because a plant is kept as a houseplant does not mean it has the same needs as every other plant kept indoors. It would be almost ridiculous to assume that every plant we chose to keep indoors just happened to have the same care needs. Further, what keeps us from calling a cactus a “houseplant”? If we used “houseplant” mix on a cactus, it would probably get root rot.

The answer, really, is that it depends. If you have found a premixed soil that works for you and your indoor plants, then stick with it! Though, I still implore you to learn why that particular mix is working for you because it is still necessary to understand your plant’s needs and how to satisfy them to the best of your ability. My opinion is that it’s useful to keep a premixed bag that can be a great base from which to amend with other elements. I actually recommend using premixed soil as long as it matches the needs of your plant.

 

What is potting mix?

Potting mix is a soilless substrate mix used for potted houseplants. There are many components of potting mix and many different types. Most mixes contain organic materials, inorganic natural materials, chemical additives, and fertilizers.

Dirt vs. Soil

Dirt is what gets on your hands and clothes and what you vacuum up off the floor. Soil is a mixture of organic matter, minerals, organisms, liquids, and gases.

Potting mix vs. soil

Potting mix and potting soil are terms that are often used interchangeably. Potting mix is strictly soilless, while potting soil may or may not contain soil. This is important because soil is not sterile and may contain bugs, fungi, or bacteria.

Potting soil vs. garden soil

Potting soil contains higher quality ingredients than garden soil. Garden soil typically contains manure and composted organic materials that hold onto water and help with root development in garden beds.

So what we are looking for as an ideal potting media is correctly referred to as potting mix. These could be premixed or made by you!

 

What can I use to make potting mix? How do I make potting mix?

Many different elements make up potting mixes. We can adjust the ratios of these elements to create an ideal mix for each of your houseplants. Typically, professional growers or vendors keep each of these elements on hand and mix them as needed. If you have enough plants to do this, I highly recommend this process because it ensures that each of your plants has adequate care (and it also makes you feel like you’re taking such good care of your plant babies!). However, most people do not have the time or resources for this as it is quite a ridiculous process. What I recommend to most is to keep a basic potting mix on hand that is a good base for your houseplants and supplement it as needed with soil amendments like the ones listed below. I will go over this at the end and list the products that I recommend.

Some terms to better understand the table below:

pH: pH measures the acidity and basicity of the media. Certain plants have different requirements. Don’t worry about doing the math; just try to keep the numbers low if your plant wants acidic soil and keep them a little bit higher if it prefers basic media. Alkaline is also another word used to describe basic. 7 is a middle ground or what is called neutral.

ph scale

Christinelmiller
CC BY-SA 4.0, via Wikimedia Commons

Water retention: Water retention is how well the medium holds onto water.

Drainage: How well the media allow water to flow freely out of the pot, rather than sitting in a puddle.

Hydrophobic: Media is hydrophobic if it resists water. You may find that this is familiar. If you haven’t watered your plants in a long time and then you do, you may find that the water sits on top of the soil and beads up. Eventually, it drains, but you find that only a think layer at the top had actually gotten wet.

Hydrophilic: This means that the media attracts and soaks up water.

 

Potting Media Amendments and What Brands I Recommend

ElementUsespHWater Retention
/Drainage
SustainableBrands
I Recommend
Coco Coir
Made from coconuts husks.
A base for a potting medium6High WT
High Drain
YesMother Earth
Peat
Decomposed organic materials that it removed from swamps.
A base for a potting medium4High WT
High Drain
NoI recommend that you do not use peat, as it is very bad for the environment, and not so great for your plants!
Sphagnum
The original form of peat moss.
Mainly used for orchids, carnivorous plants, and cuttings7Very very high WT (sometimes too high)
High Drain
YesKiller Plant
Long Fibered moss is what you want! (From New Zealand or Chile)
Vermiculite
A mineral that is mined and heated for use in soil
Aerates soil and holds onto water and nutrients but can be crushed very easily7High WT
High Drain
Sort ofPlantation Products
Perlite
Volcanic stone that is heated
Aerates the soil and hold onto water7High WT
High Drain
Sort ofPerfect Plants
Sand
Buy coarse horticultural grade.
Sand is great for a plant that is top-heavy, cover cacti soil to keep soil from drying too fast in the sun, decoration 7Medium WT
High Drain (if the sand is coarse)
Sort of questionableMosser Lee
Gravel/Rocks
Horticultural grade.
Improve drainage, cover cacti soil to keep soil from drying too fast in the sun, decorationN/ALow WT
High Drain
YesRainbow Rocks!
Rice Hulls
Horticultural grade.
Improve drainage7Medium WT
High Drain
Very!Organic Rice Hulls
BarkImprove drainage4Low WT
High Drain
YesSuper Moss
Wetting Agents
Chemicals used commercially to help ingredients become wet
Helps soil become wetN/AN/AN/A
Charcoal
Helps soak up water as well as kills bacteria
Drainage kills bacteria, protects from root rot7High WT
High Drain
Yes, certain kinds
Water Crystals
Small, super absorbent polymers that absorb water
Absorb water, water less oftenN/AHigh WT
Low Drain
Yes
Fertilizers
Slow release, or organic
Feed the plantTypically makes mix more acidicN/AN/A
Sulfur
Used to make soil more acidic
More acidicDependsN/AN/A
Lime
Used to make soil more basic
More BasicDependsN/AN/A
It has been challenging to find information on many of these elements, including why or how they should be used. I’ve only included the information that I can find. If you have any experience with particular elements, please comment at the bottom of the post and let us all know!

Coir vs. Peat

Most commercial potting mixes will be mostly composed of peat. So let’s talk about what peat is. Peat is decomposed sphagnum moss and other organic materials. Peat has been used as a growing medium for a very long time because it is hydrophilic when wet. It’s a great all-purpose growing medium, and many growers love it. However, it is being extracted from natural environments and destroying ecosystems.

Recently many growers have switched to coco coir because it is sustainable and serves a similar purpose. Not to mention, in addition to being hydrophilic, peat also becomes hydrophobic when it is dry. This means that once it dries out, it is incredibly difficult to re-wet. Typically a wetting agent needs to be added to remedy this problem. Coir seems to be the best option in every way that I look at it. It is also sterile and can help keep away pests and bacteria. I highly recommend coir over peat.

So what should I pot my houseplants in?

My main conclusion would be that buying yourself a premade mix with coir and perlite (or vermiculite) that contains no fertilizer would be best. From there, you can add your own fertilizer ratio depending on the plant, as well as add amendments as needed. You also are not contributing to the decline of peat bogs, as coir is sustainable. It is important to note that you will have to add nutrients to the soil yourself if you use this method; do not forget this step! Youc an use slow release fertilizer or something organic, or even plain old diluted liquid fertilizer.

These instructions will provide you with all you need to mix potting soil for your houseplants. If you use this method, you can find the proper amendments and fertilizers to add to this base on each plant’s page. This means that I will recommend soil amendments and fertilizers to add to your “base” depending on the plant. You will find this information in the “supplies we recommend” section of each post.

Note: This will NOT work for orchids, but it will work for succulents and cacti.

How to Make Your Own Potting Mix

  1. Purchase a base

    You will purchase a base that works for all of your plants that does not contain fertilizer. This could be anything depending on the plants you keep, but I find that a very simple mix of coir and perlite is the best option for a large collection with many kinds of plants. This can be made into basically any mix aside from orchids. Youc an use something premixed like Mother Earth’s mix, or for a cheaper option, you can mix this part yourself and set it aside until you are ready to pot your plants and add amendments. The most important part of this step is to ensure that the mix you purchase has absolutely no fertilizers, as we will be adding them later. When mixing the coco and perlite, I typically use a 60/40 – coco/perlite ratio.

  2. Add amendments

    Depending on the plant and its needs, you can now adjust the added ingredients. You can do this yourself or follow the recommendations that I provide on each plant post. This may be to add some charcoal, bark, perlite, etc., depending on the plant.

  3. Add Fertilizer

    Add the recommended NPK ratio slow-release fertilizer to the mix. I will also recommend this on the plant’s page.

  4. Adjust the pH if needed

    Some plants may require a certain pH. To change the mix’s pH, you will need a pH testing kit. This is a scenario that you most likely will not have to deal with, but just in case, this is how you change the pH of potting mix. If you need the soil more basic, you add lime or charcoal; if you need it more acidic, you add

Jane Brennan
Jane Brennan

Thanks for coming to my TED talk. Happy planting!