Why do people create their own potting mix?

Today we will cover 8 major reasons why many houseplant enthusiasts devote the time and effort to create their own potting mix blends instead of purchasing a pre-bagged mix.

This post’s goal is to help anyone that is curious:

  • To understand the reasons behind custom houseplant mixes AND
  • To have some background information that can help someone to decide whether they want to try creating their own potting mix

Table of Contents

#1 Maximizing the health of a houseplant’s roots will maximize the health of the entire plant

What we see above soil (lush foliage or a sad houseplant) has more to do with what’s happening below the soil usually.

Taking care of the plant’s roots will play a large role in determining how well a plant grows, how healthy a plant looks, how pest-resistant a plant is, and more.

What do a plant’s roots need to maintain health? The roots need:

  1. Air
  2. Water
  3. Nutrients
  4. & For the foliage of the plant to receive sufficient light

The availability of air and water to a plant’s roots is primarily controlled by the potting mix a plant is in, which makes potting mix vitally important to your plant. We will dive into why air and water are so important next.

#2 Roots need air pockets in the potting mix to thrive

In addition to water and nutrients, plant roots need air to survive and remain healthy.

Why? Roots need to breathe in oxygen and can suffocate or drown from lack of air, sort of like we can.

Where do roots find the oxygen they need? In the spaces between the components of a potting mix. The fewer spaces there are, the less air there is around the roots.

Most commercial mixes include primarily peat moss (which is dense and not super airy) with a small amount of perlite (tiny, white puffed balls). Perlite is light and fluffy like popcorn and allows for small air pockets. However, there is a very limited amount in most premade mixes.

Manually adding more perlite and other aerating ingredients (like orchid bark, perlite, or pumice for example) can help to increase air availability to a plant’s roots and therefore help to maintain plant health.

#3 Roots need a potting mix to provide adequate moisture, but not long-term wet, soggy conditions

The vast majority of houseplants are not used to long-term wet conditions around their roots.

How long does a plant need to stay wet to be considered a problem? The answer is pretty subjective, but I would say that if a plant’s potting mix is still pretty wet after a week, we should be concerned.

If the plant in question is a desert succulent or cactus, the potting mix should dry out within a few days. Any longer than that can quickly become a problem.

Peat moss (the main ingredient in most bagged mixes) often does too good of a job at retaining moisture inside our homes which receive far less light and wind and maintain much more stable temperatures than outdoor conditions.

Roots that stay in a wet environment for too long begin to drown. Dark, wet conditions invite bacteria and fungus in. This bacteria and fungus can start to feed on the weakened and dying roots, causing the plant to develop root rot and collapse.

Roots that are kept too dry are also a concern. These roots begin to crisp up and die back. Then the plant is watered and the combination of dead roots due to drought with wet, dark conditions also invites root rot.

We can avoid plants staying too wet for too long by adding aerating, drainage-increasing materials, and observing the plant regularly for signs that it needs to be watered.

If the plant is drying out too quickly, we can add in more moisture-retaining materials (like peat moss or coco coir).

If the plant is still staying wet for too long, we can add in even more drainage materials (like perlite, pumice, horticultural charcoal, or orchid bark)

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#4 Many premade mixes actually repel water when dry

Peat moss, when dry, becomes hard and compact, repelling water. In other words, peat moss is hydrophobic when dry.

The result is that water will run around the peat moss but not actually penetrate it. So if you do a quick visit with a watering can and pour a little water in the pot, the water will probably roll right off the sides of the peat moss and never touch the roots.

Adding aerating materials that break up peat moss’ ability to become a solid brick when dry will lessen the chances that no water will reach the roots.

If you are using a primarily peat moss potting mix or you have brought home a new plant in a peat moss mix and haven’t repotted, here’s how to avoid accidental drought:

The best way, in my opinion, to know whether you have sufficiently soaked peat-based potting mix is to use the weight of the pot.

There are so many times that I have drenched a plant in the sink only to pick up the pot and realize it’s still super light and almost no heavier than when I carried it over.

Sometimes I need to run water through the pot 5 or 6 times to notice that it’s starting to feel much heavier and more saturated.

Sometimes it is so compacted that I need to place the pot in a bowl of water and wait for the water to be soaked up because running water through the pot isn’t doing it.

I’ve also seen pots begin to float in a bowl of water because the peat moss has become so dry and compacted.

The best practice with these plants is to repot when you think it’s safe to do so and get them into a mix that doesn’t become a hydrophobic brick.

#5 Every person’s home conditions varies, therefore, what potting mix works best for each houseplant owner varies

There are many factors that contribute to how a plant experiences the environment including (but not limited to):

  • The average temperatures in a space
  • The humidity levels in a space
  • The amount of light entering the space (which is typically dictated by the amount of windows, the size of the windows, any overhangs or other items outside of the windows that partially block the light, the direction the windows face, etc.)
  • Where the home is located on our planet (as light, weather, etcetera, change dramatically across the globe)
  • How many plants are around the plant in question (which changes the humidity levels and potentially how much light a plant is receiving)
  • What kind of pot the plant is in as well as what size the pot is in relation to the root ball
  • And more

All of these factors affect how quickly a plant uses water. And, how quickly water is depleted within your plant’s pot is also affected by the composition of a potting mix.

You may not be able to change a lot of the other variables in your home, but you can change:

  1. The size and material of planter you use
  2. And the composition of a potting mix

to affect how long the plant has access to moisture in its pot.

#6 Harvesting peat moss (the primary ingredient of most potting mixes) isn’t super sustainable

Peat moss, the primary ingredient for most bagged potting mixes, is a product found and harvested in bogs.

Over thousands of years, plant materials submerged under water in bogs have broken down to form a type of soil called “peat”.

Dr. Leonard Perry, University of Vermont, “What is Peat Moss?” Source

Yep, you read that correctly. It takes thousands of years for peat moss to be created and the rate at which peat moss is being harvested (primarily for use in horticulture) does not allow nearly enough time for it to be replenished.

Most of the peat sold comes from Canada. Canadian companies mine their bog habitats for this product.

The Canadian peat companies will tell you that it is a renewable resource and that mitigation offsets any damage being done. This is a bold faced lie.

Bogs are incredibly sensitive habitats. They are the product of thousands of years of very particular natural processes. They hardly regenerate themselves if at all. Mitigation efforts are also pointless.

Bogs that have been “mitigated” do not return to their fully functioning state ecologically.

Matt Candeias, “The Truth About Peat,” In Defense of Plants, Source

So, are there alternatives out there to using peat moss? Yes! The most popular alternative is probably coconut coir, which is created by grinding up coconut husks (which are a natural byproduct of creating many coconut products for food and self-care products).

As with anything, using coco coir has both its advantages and disadvantages, but is certainly worth looking into. I will delve into some of the info about coco coir as a replacement for peat moss in a future blog post.

It should also be noted that most of the other common potting mix ingredients aren’t renewable resources (perlite & pumice, for example)

#7 Each houseplant has adapted to its natural environment with a specific type of nature-made “potting mix”

Every plant we see in our store’s houseplant sections carries a history of being found somewhere in the wild.

Whatever that wild environment is like is what our new houseplant has adapted to successfully grow in.

While there are some major areas around the world where a lot of our houseplants have been discovered, these areas are still quite broad in terms of climate and environmental conditions.

Some plants adapted to live in wet, tropical locations where there is lots of leaf litter, bark pieces, and other chunky stuff on the forest floor.

Some plants cling to trees, roots exposed, climbing around the forest canopy.

Others grow in sandy, rocky conditions where little water and nutrients are available.

Still, others grow in a variety of other natural conditions, like the edges of streams or clinging to rocky outcrops, and more.

But many of us go to a store to buy our bag of “houseplant mix” that is marketed as a one-size-fits-all option for all of these plants and more.

Admittedly, some people do alright with using a bagged mix for a variety of plants, but there are many others who experience difficulties (like root disease, fungal issues, pest problems, unhealthy growth, etcetera) because the potting mix isn’t matched for what the plant needs.

As plant lovers begin to care more and more about a plant’s health and become invested in setting plants up for success, it is natural to explore how to create a potting mix that is better suited to the plant’s needs (and those needs are primarily dictated by what the plant would be growing in in nature).

#8 Creating your own potting mix gives you maximum control

The 8th and final reason I wanted to cover today is that creating your own potting mix gives you the largest amount of control.

You can easily change the proportions of various ingredients in a potting mix to better fit specific plants’ needs or even to better fit your needs (like when a plant is drying too quickly and you can’t get to water it quickly enough, you can change the composition of its potting mix to allow it to go longer between watering).

Creating your own potting mix also gives you the ability to know precisely what is in the mix and what mixes work well for certain plants in your home.

The idea of mixing a custom blend can be overwhelming at first. Because of this, I will be creating a few posts to help people who are interested to learn about different soil amendments or additives and how they affect the potting mix so anyone can feel informed about their options for creating potting mix and feel safe to try it themselves.

Stay tuned for those posts. 🙂

Happy growing!

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