This page contains lots of information about potting medium or more precisely stuff that goes in it. Potting medium is generally a mix of different materials in varying quantities. This page is meant to be used as a reference. If you are trying to recreate a potting mix or trying to make your own, this page will have information on different materials you can try or alternatives you can use.
Soil
Simply put, soil is a mixture of weathered rock and humus. Of course it’s a lot more than that and there are lots to be said about soil. I recommend the Bureau of Soils and Water Management (BSWM) website if you want learn more about the soil we have in the Philippines. They even have pictures of soils from different regions. Below is a picture
of some freshly dug soil in our area.
If soil is the only stuff that will go in your potting medium it then it is your potting medium. Usually your good to go. However, if you want better results then there is a lot more to learn about soil.
- Properties
- The properties of soil varies greatly from one source to another. Most garden variety soil you find the Philippines contains a lot of organic materials and are thus considered “organic soil” as opposed to mineral soil which are mostly crushed or weathered rocks.
- Cost
- Zero. Practically free.
- Availability
- Everywhere.
- Pros
-
- It’s free.
- Easy to work with.
- Practically everywhere.
- Cons
-
- Composition varies.
- Not recommended indoors
- May contain harmful pathogens
- Also Known As
-
- Dirt
- Earth
Coco Coir
Coir (read: ko-yer) is the outer husk of the coconut nut (botanically drupes and not a nut). Coco coir is cheap and plentiful in the Philippines.
[youtube https://www.youtube.com/watch?v=Nq3t2b1ddXk]
They are sometimes called coco peat because of its similarity to another potting media called peat.
- Properties
- The physical appearance of coco coir varies slightly from one manufacturer to another. They are conveniently sold as dry, lightweight, bricks that expands to 6-8 liters of hydrated coco coir when water is added.
Coir is water retentive, chemically inert and hard to decompose.
Coco coir is a mix of granulated, soft, and water retentive materials and long fibrous and not very water retentive materials. Coir is mostly composed of the former is generally referred to as coco coir, coco dust or coco peat. Coir that is mostly composed of the latter is generally referred to as coco fiber or coco moss.
- Cost
- Cheap.
- Availability
- You can find them in garden sections of hardware stores and most gardening centers have them.
- Pros
-
- Cheap
- Provides both water retention and aeration
- Practically everywhere.
- Cons
-
- Moderately difficult to work with. Dry coir is dusty. Wet coir is messy. Easy to get under your fingernails.
- Very water retentive and may be bad for plants that doesn’t like to be wet for very long.
- Also Known As
-
- Coco Peat
- Coco Dust
Sphagnum Moss
Sphagnum or peat moss is a genus of moss consisting of nearly 400 species of moss collectively referred to as peat moss. Peat mosses is what makes up peat bogs from where another potting media called peat are sourced.
Sphagnum moss are harvested, dried and sold as potting medium or soil amendment.
- Properties
- The properties of sphagnum moss sold in the Philippines as potting media varies slightly from one manufacturer to another. They are sold as long, loose, dried, yellow to brown sphagnum material that sometimes contain dirt and other plant material. Elsewhere they are generally factory processed and sold as bricks similar to coco coir.
Sphagnum moss is absorptive and water retentive. It’s hard to decompose because of its acidity that inhibits the growth of bacteria and fungi.
- Cost
- Cheap.
- Availability
- Most garden centers have them.
- Pros
-
- Easy to work with.
- Inhibits fungal and bacterial growth
- Cons
-
- Locally sold sphagnum is not factory processed and is not sterile.
- Also Known As
-
- Dried Sphagnum
- Long Fiber Sphagnum Moss
Compost
Compost generally refers to organic materials that are decomposed in a process called composting. There are various composting methods the simplest of which is piling up or burying organic materials and waiting for it to decompose.
Compost is full of nutrients and live microorganism that plants need . Compost is generally added in potting mixes as organic fertilizer.
- Properties
- The properties of compost varies greatly from one manufacturer to another. They are mainly used for their nutritional value for plants. The amount of nutrients contained in compost depends on the type and amount of organic matter that went in the compost pile when making the compost in addition to other factors.
- Cost
- Moderately pricey.
- Availability
- Hardware store garden sections and most garden centers have them.
- Pros
-
- It’s hard to go wrong with compost.
- All natural.
- Cons
-
- Not sterile. The main selling factor of compost is the presence of good microorganisms and all natural organic nutrients.
- Also Known As
-
- Humus
Perlite
Perlite is a grey to white, light and porous material made from heating perlite (raw mineral has the same name as the finished product), an amorphous volcanic glass. Perlite is mined and crushed to what is known as crude perlite. When crude perlite is heated it expands like popcorn resulting in what we call perlite. Because perlite is mined, it’s non-renewable. There are a number of alternatives to perlite.
Perlite is porous and light. So light that it floats in water when dry which can sometimes be a problem.
- Properties
- Perlite is light, porous, and water retentive. It comes in different grades for horticulture use. Perlite is chemically inert.
- Cost
- Pricey for home growers. I’m not sure why they are expensive when they are locally made according to online sources.
- Availability
- Most garden centers specializing in hydroponic supplies have them.
- Pros
-
- Its properties makes it a must have for almost all potting mixes.
- Sterile and chemically inert.
- Cons
-
- Dusty. Wear a mask when handling them or get them wet first before handling them.
- Cost prohibitive for hobbyists.
- Algae tends to grow on its surface when exposed to sunlight and moisture.
- Also Known As
-
- Pearlite
Carbonized Rice Hull
Carbonized rice hull (CRH) is a by-product of the rice industry. CRH is rice hull (ipa) which has gone through the process of carbonization.
CRH is biochar and according to the International Rice Research Institute’s (IRRI) knowledge base:
Biochar is used as soil amendment to improve soil productivity, carbon storage, and filtration of percolating soil water (Lehmann and Joseph 2009). Libra et al (2011) have found it to have beneficial effects in increasing water-holding capacity, aeration and hydraulic conductivity, reduced tensile strength of hard-setting soils, and stimulating growth activity.
- Properties
- CRH is light and water retentive. Locally sourced CRH may contain partially burnt rice hulls, ash or other debris.
- Cost
- Cheap. It’s a rice industry by-product and we have lots of it.
- Availability
- Most garden centers have them.
- Pros
-
- Cheap and available everywhere.
- Cheap alternative to perlite.
- Cons
-
- Dusty. Wear a mask when handling them or get them wet first before handling them.
- Also Known As
-
- Charcoaled Rice Hull
Coarse Builders’ Sand (Pinagbistayan)
Locally, builders’ sand is a construction material that is mixed with concrete. Before being mixed with concrete, the sand is sieved through a mesh typically around 5mm in size resulting in finer and more uniformly sized grains . The material left in the sieve is coarse sand mixed with pebbles of varying sizes (pinagbistayan). Pinagbistayan is dirty because of the fine particles (silt) stuck on the rough surface of the larger particles. This can be removed by sieving the material again through an appropiately sized mesh with water running over the material.
Pinagbistayan is plentiful in construction areas because they are typically thrown away.
- Properties
- Size and composition of the materials making up pinagbistayan varies. They are a mix of different kind crushed rocks. Generally they are composed of dense rocks with rough surfaces and angular and sharp edges.
- Cost
- Free.
- Availability
- You can find them in construction areas.
- Pros
-
- Practically free and available almost everywhere.
- Edges are sharp and surfaces are rough which provides plenty of drainage and aeration.
- Solid. This material is hard to breakdown mechanically.
- Cons
-
- Dense and heavy.
- Washing them can take a lot of work if you need lots of them.
- Also Known As
-
- Pinagbistayan
- Pinagsaligsigan
- Grits
- Aggregates
- Grabita – Learned about this recently. The construction worker asked me if I need more “grabita.” I just assumed he meant “small graba.”
Diatomaceous Earth
Diatomaceous earth (DE) or diatomite is a soft sedimentary rock. Diatomite is composed of fossilised remains of diatoms. DE easily crumbles to a fine powder.
I have no prior experience in the use of DE for gardening because they are generally not available in the Philippines for gardening and horticulture use nor are they available in grades that can be used in gardening and horticulture. I added this section to introduce DE. Section will be expanded I get my hands on horticultural DE.
Calcined Diatomaceus Earth
Calcined diatomaceous earth is diatomaceous earth (DE) that went through the process of calcination. Calcination transforms DE into a hard, light, porous and highly absorbent material. Because of these properties calcined diatomaceous earth is used as oil spill absorbent baseball infield soil conditioner.
Calcined diatomaceous earth are commonly referred to with brand names such as Turface and Napa #8822.
- Properties
- Particle size of calcined diatomaceous earth differs between brands. Sifting is recommended to remove small particles. The product pictured above is LubeTech XR99 (an oil absorbent). It is composed mostly of small particles. It also has a neat feature of being dark orange when wet and light orange when dry.
- Cost
- Expensive.
- Availability
- Very hard to find locally.
- Pros
-
- Hard, porous, light, and absorbent. Pretty much works like perlite but doesn’t easily crumble nor float in water.
- Cons
-
- Expensive.
- Very hard to find.
- Also Known As
-
- Turface.
- Napa Floordry #8822
- Calcined Clay
- Calcined Moler Earth (moler is a variety of DE)
Pumice and Scoria
Pumice and scoria are volcanic rocks composed of highly vesicular and rough textured volcanic glass. Generally they only differ in color and density. Pumice is typically light in color while scoria is red or even black. Pumice typically floats in water while scoria sinks.
Like all rocks they come in different shapes and sizes. For horticulture use, pumice or scoria are crushed and/or sieved to be sold in different grades.
The Philippines have lots of pumice because of the Mt. Pinatubo eruption back in 1991. Most of the area surrounding Pinatubo that are once fertile farm lands are now covered in volcanic materials composed mostly of pumice.
- Properties
- Pumice and scoria are light, porous and slightly water retentive.
- Cost
- Cheap if you know where to find them.
- Availability
- Typically available in garden centers specially those that specialize in hydroponics and cactus and succulents.
- Pros
-
- Provides aeration and drainage.
- Cheap.
- Cons
-
- Pumice floats in water which can be annoying.
Vermiculite
Vermiculite is a mineral. When heated, vermiculite undergoes exfoliation. Exfoliated vermiculite is the form commonly used in horticulture and gardening.
- Properties
- Vermiculite is light, porous and water retentive. They come in a number of particle sizes for horticulture use. Because of its properties, vermiculite is commonly used is soilless growing setups.
- Cost
- Expensive
- Availability
- Typically available in garden centers specially those that specialize in hydroponics.
- Pros
-
- Provides aeration
- Retains water and nutriets and slowly releases them for plants to use.
- Cons
-
- Hard to work with. Sticks everywhere when wet.
Final Notes
This list is not exhaustive. There are a number of other potting materials I’m yet to try. This list will be updated as new information become available. Feel free to get in touch if you have questions are clarifications.
Links to Additional Resources
- http://www.bswm.da.gov.ph/PhilippinesSoils/SoilOrders
- http://www.knowledgebank.irri.org/step-by-step-production/postharvest/rice-by-products/rice-husk/carbonization-of-rice-husk
- http://www.lubetech.co.uk/uploads/asset_file/11-1070%20-%20MSDS.pdf