Peat Moss vs. Coco Coir: Which Should You Use?

Peat Moss vs. Coco Coir: Which Should You Use?

coconut coir compared to peat moss

by Matt Gibson and Erin Marissa Russell

Coconut Coir, the widely-used hydroponic
growing medium, is in recent years rising in popularity as a soil conditioner,
in many cases replacing the use of peat moss, as both are very similar
products. So, the question is, which one is the best for modern gardeners? This
argument usually comes down to a discussion about sustainability and
effectiveness. 

Sphagnum peat moss and coconut coir are both
great soil additions. Both are all-natural and plant based. Both mediums help
to break up heavy clay soils and improve water retention in sandy soils. Each
has its own separate group of nutrients that are beneficial to the soil, and
both encourage natural microbial populations. Though there are many
similarities between the two mediums, they have their differences as well, and
that’s where we will be better able to discern the better choice between the
two. 

What Is Coir?

Coir, or coconut fiber, in its many forms, is
the new kid on the block in terms of all-natural soil alternatives. Coco coir
has long been used in hydroponic gardening due to its water retention and its
deterrence of fungus gnats and certain diseases, as well as its root-supporting
structure. Though its popularity has risen in the recent past, it functions in
the garden very much like sphagnum moss.

Coco coir is a byproduct of coconut processing. The fibrous husks of coconuts are ground or decomposed in order to produce a product that is very similar to peat moss in weight and texture, but darker in color. The majority of the world’s coconut fiber comes from Sri Lanka or India.

What Is Peat Moss?

Peat moss is a traditional soilless growing
medium that comes from peat bogs. Peat bogs are swamps or marshes that are
filled with a decomposed sphagnum moss. Most peat moss in the United States
comes from Canada. The final product is a light, fluffy, soil-like material.

Peat moss became available to gardeners in the
mid-1900’s and has had a strong impact on the way we grow plants today. It has
an incredible ability to manage water efficiently and hold onto nutrients that,
in other mediums, tend to leach out of the soil much more quickly. In addition
to these benefits, peat moss also improves the texture and consistency of the
soil.

Advantages of Each

The pith of the coconut, from which coco coir
is made, contains high amounts of lignin and cellulose that prevent the
substance from decomposing and shrinking. This allows coir the ability to hold
more water than peat moss, but it is not able to hold the water as long. Coir
has a pH of 5.8 to 6.8, which is close to the neutral range enjoyed by a wide
variety of plants. This means that coir is more suited to a wide variety of
plants without needing the addition of limestone to adjust the acidity levels.

Peat moss soaks up to 20 times its own weight
in water and releases that water very slowly. If you don’t water your plants
very often, they will likely survive on the water that is stored in peat moss.
While being acidic may be a disadvantage in cultivating many plants, it can be
an advantage if you water your plants with tap water, which is often alkaline.
Peat moss is somewhat less expensive than coco coir.

Disadvantages of Each

Cows roam freely in India, and that can be a
problem for coconut coir manufacturers, as coco coir can easily be contaminated
with animal manure. Fresh water is used to extract fiber from ripe coconuts.
However, if the coconuts are not fully ripe, they are then processed with
brine, which can cause high salt levels in the coir. Coir is more expensive
than peat moss in the US because of the shipping costs of transporting it from
Asia. Using coir also requires cutting back on potassium in fertilizers and
increasing nitrogen levels.

Peat moss has an acidic base, usually around
3.5 to 4 pH. Some plants like the high acidity levels of peat moss, but
otherwise, limestone must be added to raise the pH level. Peat moss can often
contain bacterial and fungal spores that can contaminate plants. It also
attracts snails, which show no interest in coir.

Sustainability

Though industry officials tend to disagree,
peat moss is considered by wetland ecologists to be harvested at unsustainable
rates. Associate professor Alan Meerow of the University of Florida IFAS
Extension believes that peat moss is unsustainable, as they take up to 25 years
to renew after harvesting.

However, the Canadian Sphagnum Peat Moss
Association, and Jeff Ball from Garden
Rant
make an interesting case for the renewability of peat. According to
their studies, only one of every 6,000 acres of peat moss in Canada is
harvested each year, and as peat bogs are considered living entities, they are
believed to grow 70% more peat moss than what is harvested each year.

Coir, on the other hand, is always available,
as it is a waste product of coconut harvests. The outer husks are removed with
water, and processed into many products, one being soil amendments. Because
coconut fiber is constantly available and grows on trees, it is widely
considered to be a more sustainable resource than peat moss.

But not everyone believes that coir is as sustainable, nor as eco-friendly as it claims to be. Robert Pavlis at Garden Myths, believes that coir has been overhyped in this regard. Coir requires significant amounts of processing that uses lots of valuable water, which is already a limited resource in India, and leaves the water polluted after processing. His blog also cites a study that claims that working conditions in coir processing facilities cause worker health problems that would make such work illegal in Europe and the US.

Perhaps the most impactful long-term problem
from coconut coir processing is the depletion of soil nutrients caused by
growing coconuts in bulk and exporting the organic matter needed to replenish
the soil. If you take into account the environmental damage that can be
attributed to coconut farming and coir production, it hardly seems fair to
label it as sustainable and eco-friendly in comparison to peat moss.

Cost

Though mentioned in the advantages and
disadvantages sections that coconut coir is slightly more expensive than peat
moss, the difference in cost is minimal, and is largely due to shipping costs
for transportation of the products, as coconut coir costs more to transport to
the USA from Sri Lanka and India than peat moss, which usually only travels
from Canada to the US in comparison.

pH

Peat moss is acidic, with a pH level around
3.3 to 4.0, which is great for acid-loving plants, but could cause harm to
plants that are less tolerant of low pH levels. Because of its low pH, peat
moss is often used as a soil amendment to adjust and acidify soils that are too
alkaline. For most planting needs, a neutral pH is preferred, so lime is often
added to peat based soils before planting can occur. Most peat moss-based
potting soils also include lime. Coconut fiber, in comparison, has a pH range
of 5.2 to 6.8, which is much more acceptable to a much wider range of plants
without the need of additives.

Water Absorption

Peat moss tends to shed water when first
wetted, and coconut coir adjusts to water more easily than peat moss. Needing
less time to become saturated, coir also needs less water. However, despite
reports that coir has a greater water holding capacity, sphagnum peat moss
holds 10 to 20 times its weight in water, while coir only holds an average of 8
to 9 times its weight. Peat and coco coir products also come in varying
textures which can affect their ability to hold water.

Which medium is better for modern
gardens?

With the results of varying studies and each
medium having a different set of drawbacks as well as advantages, a clear
winner is not easily discernible. Both mediums have their place in the
gardening world, and both will continue to be used to improve garden soils
around the world. With all of the information in hand, only you can decide
which soilless potting alternative is right for you and your garden.

Common Questions and Answers About
Peat Moss Versus Coconut Coir

Can coconut coir be used as
mulch?

Coconut coir is a renewable resource that makes an excellent mulch for gardeners who need a mulch that offers plenty of drainage. At the same time, coir holds water—30 percent more than peat—keeping moisture accessible to plants. To use coir as mulch, soften the bricks in water for at least 15 minutes in a large container, as they will expand up to five to seven times in size after they’re hydrated. Then apply them as you would any mulch, in a layer two to three inches thick, taking care not to touch plants or trees with the mulch material. You can read more about the benefits of using coconut coir as mulch in our article on the topic.

Can I reuse my coco coir?

When the growing season is over, you can use
coconut coir again the next season, as long as you take the time to recondition
it properly. The fibers can last for years without decomposing, so it’s just a
matter of removing leftover debris and washing the material to prepare it for
reuse. First, use your hands to go through the coir, breaking up and removing
any leftover roots that remain in the coir. There are enzymes on the market you
can use to help with breaking down and removing old roots from the coir before
using it again if you like. Then wash it thoroughly in distilled water to flush
out salts left behind. Allow the coir to dry before using it again.

Can I use coconut coir for
succulents?

The drainage that coconut coir offers makes it
well suited to be a component in soil for growing succulents. Some gardeners
recommend using a mixture of half pumice and half coconut coir, while other use
three parts of a prepackaged soil blend designed for succulents, two parts
pumice, and one part coconut coir. These mixtures are not only perfect for
growing succulents; they work well for cacti as well.

Can plants grow in sphagnum moss?

Sphagnum moss’ capacity for water retention
makes it a good choice for plants that thrive in moist soil. To use sphagnum
moss in your container garden, first pick through the moss to remove any large
pieces of grass, weeds, or other foreign debris it may contain. Soak the moss
in a container of lukewarm water for a while, then remove it when you’re ready
to use it and squeeze it out to remove most of the water so it isn’t saturated.
Add a layer of sphagnum moss to the bottom of the container you’ll use, then
add the plant, positioning the root ball in the middle of the container and
filling in around the edges with more sphagnum moss. Pack the moss tightly
enough to keep the plant in place when the container is tipped to one side.
Water deeply, or you may choose instead to submerge the container in lukewarm
water and let it soak until it stops producing air bubbles. Whenever the moss begins
to dry out, it’s time to water the plant again. Try not to let the moss become
completely bone dry in between waterings for best results. Use a fertilizer
appropriate for what you are growing to feed your plants, as sphagnum moss
doesn’t offer much in the way of nutrients.

Can you compost coconut coir?

Coir makes an excellent ingredient for composting because the carbon it contains helps to counterbalance the nitrogen in other ingredients, such as kitchen scraps. Use two parts coconut coir to one part green materials or one part coconut coir to one part brown materials. You can read our article on compost ingredients to learn about green and brown materials and what is suitable for composting.

Can you grow plants in just peat
moss?

Plants that thrive in moist conditions can be
grown in peat moss alone, or you can mix it with potting soil if your plants
don’t need as much moisture. Use peat moss as you would any planting soil,
watering when it becomes dry but not allowing it to dry out completely before
the next watering. As an alternative to standard watering methods, you can soak
container plants growing in peat moss in lukewarm water until they stop
producing air bubbles for a deep watering. Because peat moss doesn’t offer much
nutrition, be sure to use an appropriate fertilizer to keep your plants
healthy.

Can you mix coco coir with soil?

You can mix coconut coir with soil, using up
to 80 percent coir, to create a soil blend that drains well and lasts for years
without decomposing. Coir is often sold in bricks that need to be soaked in
water before use. Refer to the package for instructions on how much water to
use with your brick of coir, and soak it in a large container. Coconut coir
will expand up to five to seven times in size when it’s hydrated. Once it’s
soaked, mix the coir with your hands to break up any clumps and separate the
fibers. Then mix it with the soil you plan to use. The standard ratio is half
coir and half soil. You can add compost at this time if you desire, or add one
part perlite or vermiculite to further increase drainage. Then use your coir
and soil blend as you would any planting medium.

Can you mix peat moss with
potting soil?

Yes, peat moss makes a perfect component when
mixing your own potting soil, especially for plants that need extra moisture.
You can create your own blend by mixing one part peat moss with one part sand
or vermiculite and one part compost. After combining these ingredients, add
half an ounce of pelleted limestone and a quarter of an ounce of super
phosphate or triple phosphate for each gallon of soil mixture. Increase the
peat moss for moisture-loving plants, or add more perlite if you’re growing
plants that require a drier soil.

Can you over water coco coir?

As with any planting material, it’s possible
to give plants too much water when they’re growing in coconut coir. Generally,
water plants growing in coir every day or two, and keep adding water until the
moisture drips from the bottom of the container. If the coir is drying out
before the day is up, consider moving plants to a larger container that will
hold more moisture, keeping the water available longer so you don’t have to
water them as often.

Can you start seeds in peat moss?

Because peat moss holds moisture so well, it’s
optimal for starting seeds. You can start seeds in peat moss by itself or
create a blend using one part peat moss along with two parts soil and two parts
sand or vermiculite. Wet the soil before sowing seeds, and follow the directions
for the seeds you have regarding how deep to plant them, as different types of
seeds should be planted at varying depths. Lightly mist the seeds once they’re
planted and cover them to keep humidity up with a lid, if your container came
along with one, or use a clear plastic bag. Mist as needed to keep the soil
evenly moist. Keep the seeds somewhere that stays between 65 and 75 degrees
Fahrenheit where they will receive bright indirect light.

Do you water coconut coir every
day?

Most plants growing in coconut coir need to be
watered every day or two. You should water your plants until the moisture drips
from the container’s drainage holes. If the coir is drying out too quickly,
moving plants to a larger container will keep you from having to water them so
often.

Does adding peat moss make soil
acidic?

Peat moss is acidic, so depending on the pH level of your soil, it can increase its acidity. The pH level of peat moss is around 4.4, while neutral soil will have a pH of around 7. Some plants thrive in acidic soils, such as blueberries and azaleas. If your soil is already acidic and you aren’t growing acid-loving plants, peat moss is probably not the best planting medium for you. If you aren’t sure of your soil’s pH level, you can learn about testing to determine pH in our article “How to Test pH in Your Soil”.

Does coco coir go bad?

It takes years for coconut coir to decompose—some
sources say decades. It can be reused for the next season, too, since it lasts
so long. If you’d like to reuse your coconut coir, after the growing season has
ended, go through the material to remove plant debris and any root pieces. Then
soak it in lukewarm water for a while to clean it. Dry the coir before
replacing it in your garden.

Does coco coir have nutrients?

Coconut coir does not provide plants with much
nutrition, so it’s important to either use it mixed with a potting soil that
contains the nutrients your plants need or to use it in conjunction with an
appropriate fertilizer. Coconut coir is high in potassium, however, and it also
contains manganese, copper, iron, and zinc.

Does coconut coir decompose?

Coconut coir does decompose, but it takes a
long time. Your coir will be durable for years, and some sources even claim it
lasts for decades. It can also be washed and reused season after season.

Does peat moss add nitrogen to
soil?

Peat moss is low in nutrients and does not add
nitrogen to soil.

Does peat moss go bad?

Peat moss that has not been used does not
expire and can be used after a period of storage. However, peat moss that has
been used may have reduced ability to retain water as well as reduced acidity.

Does peat moss have any nutrients?

Peat moss is low in nutrients, so it’s
important to either combine it with nutrient-rich potting soil or use an
appropriate fertilizer if you’re growing plants in peat moss.

How do you amend soil with peat
moss?

To amend soil with peat moss, first put the
peat moss in a large container and add water, then stir. Allow the water and
peat moss to soak for a while, then add more water. Continue this process until
the peat moss is completely saturated. When you squeeze a handful of the peat
moss, a drop or two of water should come out, but you don’t want it so wet that
a stream of water escapes when it’s squeezed. Then spread a layer of two or
three inches over the area you wish to amend. Till or mix the top twelve inches
of soil to work the peat moss through your garden’s topsoil.

How do you rehydrate coconut
coir?

Coconut coir is usually sold in dehydrated
bricks that you must rehydrate before the coir is ready to use in your garden.
Use a large container to rehydrate your coconut coir, as it will expand five to
seven times in size when rehydrated. Refer to the instructions on the packaging
to tell you how much water needs to be added for your specific brick of coir.
Allow it to soak, then mix the rehydrated coir with your hands to break up any
clumps and separate the fibers. After you’ve mixed it, the coir should loosen
and have a fluffy texture. Once it’s fluffy, it is ready to use.

How much lime do I add to peat
moss?

When using dolomite lime to raise the pH of
peat moss, the amount of lime to add varies depending on what you will grow.
Plants that thrive in acidic soil, such as blueberries or azaleas, do best with
just a sprinkling of lime. For growing vegetables and other plants that don’t
thrive in acidic conditions, add between half an ounce and one and a half
ounces of dolomite lime per gallon of peat moss.

How much water do I add to coir
bricks?

The amount of water you’ll need to rehydrate a
brick of coconut coir varies depending on your particular brick, but as a
general rule, use eight parts water to one part coir.

How often do you feed in coco?

Because coconut coir does not offer any
nutrition to your plants, use fertilizer each time you water them.

How often should I water plants
in coconut coir?

Most plants growing in coconut coir need to be
watered every day or two. You should water your plants until moisture drips out
of the container’s drainage holes. Should you find that your coir dries out
quicker and you’re having to water your plants more frequently than once per
day, you can move them to larger containers so you don’t have to water them as
often.

Is coco peat the same as coir?

Coconut coir and coco peat are the same
material; the terms are interchangeable.

Is coconut coir organic?

Coconut coir can be an organic product when it
is manufactured under organic conditions. However, not all coconut coir is
organic. Check the packaging of coconut coir for the term “organic” when
shopping if you’re looking for organic coir.

Is coconut coir flammable?

Coconut coir is not flammable.

Is coconut coir good for seed
starting?

You can use coconut coir for seed starting,
and many gardeners report success starting seeds in this growing medium.
Rehydrate your coir blocks, referring to the packaging to determine how much
water to add. Use a large container when rehydrating, as the coir will expand
five to seven times. Mix it with your hands to separate the fibers and break up
any large clumps until the coir is fluffy in texture. Then it’s ready to be
used for seed starting just as you’d use any other planting medium.

Is coconut coir toxic to dogs or cats?

While coconut coir is not poisonous to dogs or
cats, the dehydrated coir will expand when water is added. If the dehydrated
coir is ingested, it can expand in the pet’s digestive system and cause
intestinal blockage. If your pet has consumed dehydrated coir, contact your
veterinarian.

Is coconut coir toxic to humans?

Coconut coir is not likely to be ingested as it
is not particularly appetizing. However, should dehydrated coir be eaten, it
will expand when water is added, and if this expansion occurs in the digestive
tract, it can cause intestinal blockage. If a person eats dehydrated coir, they
should contact their doctor or the Poison Control Hotline at 800-222-1222.

Is peat moss good for clay soil?

Peat moss is a good amendment for clay soil because it loosens the clay’s thick, heavy texture. Spread peat in a two-inch layer over the area you wish to amend, then mix it to a depth of four to six inches. For more on how to optimize clay soil for gardening, refer to our article “Amending Clay Soils”.

Is peat moss good for blueberry bushes?

The acidity peat moss adds to soil makes it
especially beneficial for acid-loving blueberry plants.

Is peat moss toxic to dogs or cats?

Peat moss is not poisonous to dogs or cats.
However, if pets ingest peat moss, they may suffer gastrointestinal irritation,
including nausea, diarrhea, or vomiting. If your pet has digestive irritation
after ingesting peat moss, contact your veterinarian. If pets roll in peat
moss, they may also experience skin irritation. If your pet’s skin is irritated
by peat moss, rinse their coat with fresh water. If peat moss comes into
contact with the eyes of your dog or cat, it can also cause irritation. Should
this occur, hold one eye open at a time, and rinse your pet’s eyes out with
fresh water, saline, or pet eye wash. Continue until they have been rinsed out
well. If eye irritation continues, consult your veterinarian.

Is peat moss toxic to humans?

Peat moss that contains the fungus Sporothrix
schenckii can infect humans with sporotrichosis if the spores enter a person’s
bloodstream through broken skin, such as a cut. When using peat moss, gardeners
should reduce the risk of contracting sporotrichosis by wearing gloves, long
sleeves, and long pants so skin is not exposed.

Is there a difference between
peat moss and sphagnum peat moss?

Sphagnum peat moss and peat moss come from the
same plant, but sphagnum moss is made of the dried plant, which may be milled
to shorten the fibers. Peat moss that is not labeled sphagnum moss is made of
the dead layers of moss that live moss grows on top of. As such, peat moss may
contain parts of other plants, twigs, or anything else that was on the ground
before the next layer of moss grew on top of it. Sphagnum moss has a neutral
pH, while peat moss is more acidic, with a pH level around 4.4.

What are the advantages of coir?

Coconut coir has many advantages in gardening.
It provides excellent drainage while still holding moisture to make it
available for plants. It takes years to decompose and can be washed and reused
season after season. It is also sterile and free of bacteria that can spread
diseases to plants.

What are the benefits and
advantages of peat moss?

Peat moss has many benefits and advantages in
the garden. It adds acidity to soil, making it particularly beneficial to
acid-loving plants like blueberries and azaleas. It takes years to decompose,
making it an economical and practical soil medium or amendment. It also retains
water well, holding several times its weight in moisture and keeping it
available for plants. Although peat moss does not provide nutrients, it retains
nutrients from fertilizers well so plants have easy access to them. It also
does not contain the seeds from weeds and detrimental microorganisms that can
be found in some composts.

What grows well in peat moss?

Peat moss has an outstanding capacity for
holding moisture, making it optimal for seed starting. Its acidity also makes
it a good choice for any plant that thrives in acidic soil, such as
blueberries, azaleas, or camellias.

What is coconut coir made of?

Coconut coir is a natural material that is made of the fibers between a coconut’s hairy coat and its hard outer shell. 

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