Potting Mix
Welcome to our third lesson in CP Heaven's learning lab!
Today we will be learning about the potting mix. There are numerous types of potting mixes in the market, and each has unique ways of helping your plant grow better.
There are 2 main types of potting media. Organic and inorganic.
I've listed the common ones we have below.
Inorganic
-
Perlite
-
Charcoal
-
Sand
-
Volcanic Rock
-
Pumice
-
Leca Balls
-
Vermiculite
Organic
-
Sphagnum peat/moss
-
Coco peat/chips
-
Orchid bark
You might be wondering what is "inorganic" and "organic".
Inorganic potting media are materials that aren't derived from plants and animals. They can be anything that we can use to grow our plants in. For example, plastic and even glass!
Those that I've listed above are common media that gardeners use for growing plants and can be easily found in gardening shops. But we can use anything we can find! We just have to test them out to see if it works. 😁
Now let's have a look at the organic media.
Organic potting media are materials derived from plants and animals. They are things we can usually find everywhere like eggshells, coconut husk, dry tree barks, and even toilet paper!
So why do professional gardeners and landscapers choose what I've listed above instead of using things like toilet paper? Let's get to it.
Plants as we all know are living things. And most living things that we know of require air (oxygen/carbon dioxide/etc) and water. The plants that we usually grow take up water through their roots system and that roots are anchored onto a growing media.
But is the sole purpose of the root to just take up water and hold on to the ground?
The short answer will be no. The roots not only do the above but also take up minerals in the growing media for growth. Furthermore, it also requires air. Without proper ventilation and the ability to hold on to the minerals in the media, some plants will develop rotting in the roots and experience growth deficiencies.
PH (Potential Hydrogen) of the growing media directly affects the amount of these minerals that are soluble in it.
Every plant has its different needs for air, water, minerals, and PH. To make sure we have what we need for the plant that we are growing, we will have to understand how much of these are required for it.
First, we have to observe where the plant grows naturally in its native environment. By observing, we are trying to figure out how much water, air, minerals, and PH are in their native media. After that, we should prepare a mix of the list above to try and mimic its native environment in terms of water, air, minerals, and PH that it should prefer to grow in.
By doing so we are "cooking" a mix of growing media for our specific plant. Like cooking, we have to understand how each of our ingredients works.
Plastic wool & Glass wool
Perlite
This material is a form of volcanic glass formed naturally.
Pros:
-
It is inexpensive and very light in weight.
-
Gives a lot of air to the roots as it's very porous.
-
Fast draining
Cons:
-
Break up easily and becomes powdery, which will be bad for your health when inhaled.
-
Creates a mess when there's heavy watering or downpour because it'll float to the top of the mix and even wash away easily.
-
Turn brown easily and algae grow on it easily when in contact with fertilizer and exposed to light.
Charcoal
This material is carbon derived from burnt wood.
Pros:
-
Lightweight
-
Contains minerals that can be used by plants
-
Balance out acidic soil
-
Loosen the soil due to its porous
-
increase drainage
Cons:
-
Dirty your hands black
-
It can turn your soil too alkaline.
Sand
The sand that we are referring to here is well-washed river sand. They are harvested from rivers and are considered non-sustainable. They are made up of silicon and oxygen, also called silica sand.
Pros:
-
Improves resistance to abiotic stress (better resistance to drought and heat)
-
Improves resistance to biotic stress (making it less threatened by bacteria and fungi)
-
Fast draining
Cons:
-
Cannot hold on to minerals required by the plants well
-
Becoming more expensive
-
Not sustainable
Volcanic rock
As the name suggested, this is a rock from a volcano. It has many properties which we like to use it for.
Mulching - This is an action when we place a layer of materials on the top area of our growing media to protect the layer below from, excessive water loss through wind and heat, and prevent weeds from growing in the soil below.
Pros:
-
Light in weight
-
Porous
-
Able to be used as mulch well
-
Will not decompose
-
Good drainage
Cons:
-
Not hold on to the fertilizer you put in very well
-
Expensive
-
Fly in strong wind and can be dangerous if fall from high ground or even fling away by a grass cutter.
-
Gets hot easily and may damage roots if it gets too hot.
Pumice
Like perlite, this is also volcanic glass, and it does float on water. Unlike perlite, it is bigger and isn't as brittle. Its primary use can be just like perlite but better. Therefore, it is much more expensive when compared to it. It's also non-toxic.
Pros:
-
Light in weight
-
Porous
-
Will not decompose
-
Good drainage
Cons:
-
Not hold on to the fertilizer you put in very well
-
Expensive. even more than volcanic rock.
Leca ball
LECA stands for Light Weight Expanded Clay Aggregate. They are made up of clay that had been superheated. It floats on water naturally, but you should soak them in hot water before using it. When soak in hot water, the balls will sink. It's extremely porous but it does not hold nutrients well. Can be used as mulch due to it being a bad heat conductor due to being extremely porous. It's super well-draining too.
Pros:
-
Light in weight
-
Porous
-
Will not decompose
-
Good drainage
Cons:
-
Not hold on to the fertilizer you put in very well
-
Expensive. even more than volcanic rock.
Vermiculite
vermiculite is a natural mineral made up of magnesium, aluminum, and iron silicate.
This is a very strange mineral; it can hold water very much like a sponge. In cooler or drier climate countries, growers will use them to germinate seeds and even just grow their plants with 100% of them. It can also hold onto nutrients very well.
But in an extremely hot and humid country like Singapore, it causes complications like root rot easily.
Pros:
-
Light in weight before it absorbs water
-
Will not decompose
-
Holds on to a large amount of water. As much as 3 to 4 times its weight.
-
keeps the roots cool and wet if the environment is dry.
-
Hold on to fertilizer
Cons:
-
Does not function well in hot and humid places.
Sphagnum moss
This is dried moss. Its primary use is to be used as a soil alternative. This is especially true for orchids and pitcher plants. It is very good at holding water and minerals and is also acidic naturally. It can hold on to around 20 times its original weight! Wet and acid-loving plants love this media very much. Can also be used to stop media in the pot from flowing away through the drainage holes when it is placed at the bottom of the pot.
Pros:
-
Light in weight before it absorbs water
-
Holds on to a large amount of water. As much as 20 times its weight.
-
Keeps the roots wet at all times.
-
Acidic in nature
-
Hold on to fertilizer
-
Easy to handle
Cons:
-
Decompose
-
Very expensive
Sphagnum peat
This is a fully decomposed sphagnum moss that took hundreds of years to form in swamps, it is also a soil alternative. This material is very good for germinating seeds and also growing plants. It is naturally acidic and seedlings love them. It also holds onto nutrients very well. Many farmers would love to use these for their farm if they can due to them being the almost perfect growing media for many vegetables. But it's not a sustainable material.
Pros:
-
Light in weight before it absorbs water
-
Holds on to a large amount of water. As much as 20 times its weight.
-
Keeps the roots wet at all times.
-
Acidic in nature
-
Hold on to fertilizer
-
Easy to handle
Cons:
-
Decompose
-
Very expensive
-
Not sustainable
Coco peat
Coco peat is a cheaper alternative to sphagnum peat. It can be used just like sphagnum peat but is of poorer quality as it does not lower soil PH and decompose faster. It's also very inexpensive.
Pros:
-
Inexpensive
-
Hold on to water very well
-
Hold on to nutrients well
-
easy to handle
-
Keep plants wet at all time
-
Sustainable
Cons:
-
Decompose very quickly
-
Does not lower PH
Coco chips
Coco chips are a form of coconut husk that had broken into pieces. Size ranges from 1cm to around 1 inch. They are normally mixed with potting soil or other soil-like media like cocopeat for aeration purposes. It's able to hold on to nutrients and water relatively well, and on top of that, its structure is also good for roots to take hold of. It needs to be replaced after it had decomposed. And as it decomposes, the aeration of the soil will get poorer.
Pros:
-
Lightweight
-
Extremely cheap
-
Sustainable source
-
Hold on to water and nutrients well
-
Good grip for root
-
Aeration of potting soil and soil-like structure media
-
Slightly lower PH
Cons:
-
Will decompose
-
Hard to use it alone as it has huge spaces in between each chip.
-
Floats on water if it gets too dry.
Orchid Bark
Some people like myself thought this is a bark of an orchid plant, but I couldn't be more wrong. Orchid bark is a bark of a tree, most commonly a fir tree. This media is very good for plants like aroids because it can be fast draining and also retain some water and nutrients.
Pros:
-
Good for plants that love to cling to trees. (epiphyte)
-
Retain just enough water for aroids and therefore prevent root rot.
-
Retain some nutrients
-
Provide a lower PH
-
Affordable price
Cons:
-
Will decompose
-
Might contain toxin that is harmful to pets.
-
PH might get too low to like 4 PH
Congratulation! We have once again reached the end of another lesson! I hope that you learned something from this lesson because I know I too learned much when writing it. The charts above are a rough gauge of what I think their properties are so please take it with a pinch of salt. 😊
If you like this content and would like to support it, you can simply make a purchase on my shopee store!