New growers frequently find it challenging to master the different soil types and different growing media available for their garden.
There are dozens of different soil types, growing mediums, and bags of dirt on the market, all promising larger plants and better results with little real guidance to help beginners make the best choice.
I’ve both succeeded and failed with more than my share of different plants with a variety of soil quality and composition, and the bottom line is that you’ll do your best once you get a grip on the different ways soil and growing mediums like coco coir behave.
When you mix up different bits and pieces of growing mediums and soils in the name of plant growth, it can feel a bit like alchemy. But get those basics down, and it’s not just a lot of fun but a fantastic way to get your plant life thriving for a long time to come.
Let’s jump in and discover a bit more about the similarities and differences between coco coir vs soil.
Table of Contents
What is Coco Coir?
Coco coir is made from the external fibers found on coconuts. Straight from the tree, coconuts have a thick, strong outer shell called the husk.
The first step in processing the nut is to remove the bust. Once dry, it’s next broken down into tough fibers of different lengths.
The long, strong fibers of coconut husks are traditionally used for a bewildering array of purposes, including ropes, fishing nets, and even used for building. Shorter fibers are sometimes sorted and used to make brushes and the like.
Most gardeners know coco coir in one of a few forms – usually as absorbent horticultural matting or as a soil amendment.
Coco coir mats are used to line hanging baskets, especially for moisture-sensitive tropical plants like orchids. It’s woven from long fibers and is tough and enduring.
The other common form of coco coir is the humble dehydrated coir brick. A coir brick is a glamour-less lump of compressed brown coco fiber that expands greatly when wet.
The shortest fibers processed like this are sometimes called coco peat or coco soil, but it’s much the same in practice.
Once rehydrated, the coco coir mix is loose and crumbly, wonderfully airy, but able to hold lots of water and nutrients. It’s got a lot of potential, no matter how you garden!
This next section covers coco coir vs soil so you can gain a better understanding of what you’re working with!
Comparing Soil to Coconut Coir
Stupid question, right? Everyone knows what soil is!
If we’re going to compare coir to soil, however, it pays to identify what exactly soil is first.
Organic soil is a mixture of natural materials like rotted leaves and manure, worked through with minerals like sand, silt, and clay. If left to its own devices, it forms an ecosystem, the plants above supporting life below the soil level.
Down under the ground, earthworms, pill bugs, and other tiny critters like soil mites work to break down old leaves and the like, and friendly fungi form relationships with the root systems of trees and other plants.
Good soil has poetry and beauty all its own.
As a result of these complexities, garden soil has wildly differing characteristics depending on where you are. Local geology plays a big part in the chemistry of garden soil.
Each specific type of soil, with its own ratio of clay, sand, and stones, releases nutrients in different quantities. These differences will have an impact on things like drainage, too.
Differences in the organic material worked through the soil will alter how it retains water and oxygen and impact the microscopic communities of fungi and bacteria that provide their own unique benefits that are hard to replicate in a synthetic soil mix.
Finally, the actions of large animals – including human gardeners! – will have a special part to play.
Manure adds nutrients, and the physical action of digging, planting, and tilling changes how all these different elements interact. There’s a lot going on in garden soil!
Potting soil is a different matter. Here, the properties are more driven by the economics of the product.
A good quality potting soil is an excellent growing medium. It will contain a lot of organic matter and the right amount of inert mineral components to provide better drainage and support root development. Many commercial potting soils work wonders with coco coir, as the coco coir helps with drainage and structure.
Slow release fertilizers are common in commercial potting soils to provide enough nutrients to ensure a healthy plant – something coco coir is lacking. The best commercial soil blends are even inoculated with the spores needed to kick-start life below the surface.
Cheap stuff is usually just inert matter with a paltry amount of thoroughly degraded plant material. It’s not great on its own, but it can make a very economical starting point to blend your own specialist growing media for pots and containers.
Finally, some companies sell bags of dirt that are mostly mineral components with few necessary nutrients. It’s sold for backfill rather than as a growing medium, but it rates a mention here. Beginner growers on a budget sometimes buy it by mistake, resulting in an abysmal level of growth, indeed, if you see any at all.
Growing with Coco Coir (Advantages & Disadvantages)
Once you take a deeper look, it’s not hard to see that garden soil is a far richer growing medium than pure coco coir.
Coco coir is a simple material, a natural fiber that can be used to grow but doesn’t have the same complexity as natural soil. Even bagged potting soil has more going on.
But that doesn’t mean that coco coir is a subpar product. In fact, that simplicity has a value all its own. Let’s take a look!
Benefits of Coco Coir
Coco coir’s main claim to fame is its excellent water-holding capacity.
Dump a brick in a bucket, and it can draw close to 40% of its weight in water. It’s just about the best medium to keep plants well hydrated without overwhelming the plant’s roots, all while providing excellent drainage.
As a result, coco coir is often used in loose soilless mediums for air plants.
Coco coir also holds nutrients well. Agricultural scientists talk about the Cation Exchange Capacity of growing media, a shorthand for how well the various nourishing minerals stick around in a substance.
For most gardeners, it’s enough to know that a medium with good CEC actively draws up and secures nutrients. It’ll hold any fertility you give it well.
Coco coir is also great for breaking up clay soil or providing fertility to sandy ones. Both types of soil need all the extra organic material they can get.
Aged composts and well-rotted manure are best for this task, but they take time.
Coir, on the other hand, is ready to go once it’s been drenched. Because it holds nutrients so well, it can provide a substantial kick start when rehabilitating exhausted soil or as a foundation for new beds ahead of the growing season.
Coco coir is also one of the most sustainable organic soil amendments.
It’s made from what would otherwise be considered a waste product – indeed, prior to its use as a growing medium, large mounds of the stuff would simply build up in coconut groves or be shipped to a landfill.
Using it in the garden not only keeps this versatile stuff out of the waste stream but also provides coconut growers with a second income stream.
This makes coco coir an excellent alternative to peat moss for growers looking for a sustainable choice. It has essentially the same properties but doesn’t come with a devastating footprint.
If the above benefits aren’t enough, one study showed that coco coir fibers achieved 80% absorption of heavy metals in water in just 10 minutes! This makes it a great choice and one of the best ways to ensure your tap water doesn’t harm your plants.
Potted Exotics Pro Tip: Coco coir makes a great addition to rosemary soil, so consider including it in your culinary garden.
Disadvantages of Coco Coir
Coco coir’s most significant disadvantage is that it’s pretty low in nutrition, which isn’t ideal for plants that need adequate soil nutrition to thrive – like Pothos.
If you’re growing in coco coir alone, you’ll have to add fertilizer to the growing medium at a significantly higher rate than if growing in soil. It also tends to lock away certain nutrients like calcium and magnesium and oversupply others like potassium.
Grow in coir alone, and you really need to watch out for nutritional deficiency.
You also have to watch your water levels.
It’s really easy to over-water a plant grown in coir alone. It might start off nice and airy, but as the plant spreads roots into air pockets and the material itself decomposes, those pockets vanish, and all you’re left with is a heavy, damp material.
Finally, cheap coir is often very salty indeed!
Traditional processing involves soaking the husks of coconuts in water until the bulk rots away, leaving only the fiber behind. In many coco growing areas, seawater was used for this purpose.
Most coir is rinsed with fresh water these days, but unscrupulous supplies have been known to slip dodgy stuff into their coco bricks. It pays to check!
Best Uses for Coco Coir
Coco coir is my go-to organic additive for indoor plants and other container growing. It can’t be beaten when keeping your plants well hydrated without smothering them, especially when mixed into other materials.
My standard soil mix for indoor plants is a simple one-third each coco, perlite, and good quality potting soil. It has an ideal balance of water retention, aeration, and fertility for just about any indoor plant.
When worked into clay-rich or sandy ground, it starts to break down and encourages the fungi needed to kick start healthy soil ecology.
Hydrate the coir thoroughly and work it through the soil with a hoe, pitchfork, or other tools. It’ll help loosen the soil up and make space for root systems and the friendly fungi they love.
I also find coco coir one of the best growth media for seed germination. Seeds are self-contained and do best in low fertility growth medium that will inhibit pathogens.
Coir will keep the seeds moist enough to germinate without risking rot or infection. It’s a great way to keep fussy seedlings at that sweet spot where they are moist without swimming in too much water.
Coco vs Soil (Common Questions)
Can I Use Coco Coir in Hydroponic Systems?
Coco coir is a popular hydroponic growing medium for home hobbyists, organic growers, or commercial growers, and it’s an excellent choice for growers after a renewable resource. Its high water retention ensures the nutrient solution reaches the plant roots, and the high Cation Exchange Capacity keeps it there.
The natural pH range for coco coir is comfortably neutral, allowing confident use more or less straight from the bag.
It’s got a few benefits outside the system, too.
It’s easy to find and cheaper than clay pebbles and is far more environmentally friendly than other hydroponic media. Not only does coir reuse coconut fiber that would otherwise go to waste, it’s biodegradable and breaks down over time.
Other substrates like Oasis or Rock wool wind up in landfill after use, but coir can be composted or added to garden soil once the hydroponic system is cleared out.
Looking to start your seedlings in hydroponics and move them outdoors when the temperature rises? Check out our article on how to move plants from hydroponics to soil!
Can I Use Coco Coir Alone As Potting Soil?
It’s not advisable to use pure coconut coir to grow plants. It’s just not a complete material like natural soil, and it wont hold water very well. Coir has little nutrition of its own and breaks down quickly when compared to other mediums.
That’s not to say you can’t use it as potting soil if you really want to.
A good practice is to fertilize regularly and monitor the condition of the coir. Once it starts to compact, you can re-pot as usual; no harm done.
Many growers enjoy the complete control this sort of growing medium can provide.
If you want to experiment with the best soil free growing method but don’t want the fuss of hydroponics, you can blend coir products with other amendments into a soilless potting mix. Coco mixes maintain the correct nutrient levels and oxygen levels around the root zone and help keep proper nutrients at the ready.
Potted Exotic Pro Tip: Fussy plants like indoor begonias do well in a soil free mix. My best results have come from a mix of equal parts coco coir, vermiculite, and perlite. It allows excess water to drain while ensuring good nutrient uptake and spectacular growth.
Is Growing in Coco Faster than Soil?
If you keep an eye on the nutrient level in your coco coir, you can see impressive rates of growth that are far faster than those found in soil-grown plants. The catch is, of course, that you must perform a lot more labor to get there.
You must provide a complete fertilizer regularly and in doses that don’t cause root or leaf tip burn. You also need to watch for nutrient deficiency diseases. Finally, you have to be mindful of your pH levels.
How is Coco Coir Made?
Coco coir is made from the fibers that cover the outside of a coconut. Before extraction, the coconut is soaked in hot seawater (a process called retting), which makes the fibers easier to remove by crushing and “combing” the shell.