Coconut Coir Tutorial

Those who watch the show know I use a lot of coconut coir. You see, I hate peat moss, I HATE IT. Hate those stupid peat pots, hate the little Jiffy pellet things. Peat moss has two settings: too wet and too dry. It grows algae, it attracts fungus gnats. I hate it. So I use coconut coir despite the fact that the entire history of horticulture seems to be based on peat moss. Peat moss may in fact be better for plants, but I hate it. HATE IT!

So I use coconut coir. It is the waste product from coconut’s outer husk. The shell you see in the grocery store has had this outer husk stripped off, and the large and fibrous husks are used for doormats, upholstery, mattresses etc. The “fines” used to be considered trash, and places like Sri Lanka literally had mountains of the stuff laying around. Someone had the bright idea to use it as a peat substitute, and my life got a little brighter, because I HATE peat moss. Now, the fibers used to be soaked in brackish lagoons, so there were some early problems with salinity, but if you get a good horticultural grade it should be leached out and there won’t be any problems with this. I’ll also be showing you a little trick which might help with this, just in case. Coir holds just the right amount of moisture, and when it does dry out, it remains hydrophilic (receptive to water). It is less dusty than peat, seems to hold more air, smells good, and doesn’t break down as fast. Finally, it is a good use of a “waste” product.
So for those of you who are unfamiliar with this material, here’s a little how to:

Dry brick of coir

The coir usually comes dried and compressed into bricks. You can get sizes ranging from a builder’s brick on up. The one shown is the equivalent of the small bricks and is a quarter of a large pack.

Breaking up dry bricks

If you have one of the small bricks, just throw it into the bottom of a five gallon bucket. If you need to break one up, go in along the side, and pry it apart as shown.

Coir chunks

Here you can kind of see the fibrous nature of the stuff. One brick takes one gallon of water to rehydrate.

Add gypsum to the warm water

I have been adding gypsum to the water before adding it to the coir. Use warm water, and add about a tablespoon of pearled gypsum. Shake it up. The pearls won’t completely dissolve and that’s fine. The water will look a little muddy as shown. This helps with any residual salinity, adds calcium and sulfur, and helps with any potassium imbalance that can occur when using coir.

Addendum: I noticed a possible magnesium deficiency in my pepper starts when using a 1:1:1 ratio of coir, vermiculite and perlite. Obviously, this seed starting mix doesn’t really contain any nutrients, and is only for the first few weeks of growth. However, even when the plants started getting a weak fertilizer solution, they showed interveinal chlorosis which seemed to clear up after a dose of epsom salts (magnesium sulfate). I’ve started to experiment with putting a tablespoon of the epsom salts in the gallon of water along with the gypsum slurry. I’ll give an update on any results as soon as they are known.

Addendum: Again with the peppers, again with the chlorosis. I think it had as much to do with irregular watering (too dry, then too wet) as with any deficiency. Still, letting them dry out, then giving epsom salts seemed to perk them up, and once I potted them up, they really took off. I’ve been putting the epsom salts in the soak water for a couple years now, and again the results are inconclusive, but it certainly isn’t harming anything at this concentration.

Add water

Add the water, just dump it all in. Notice how dark the coir is where the water has hit it. You can really tell moisture levels in coir by the shade. Dark equals wet, light equals dry.

Starting to hydrate

This is after a couple minutes. You can see how there is a little bit of light shaded coir that still isn’t hydrated. You can start breaking up chunks and mix the wetter with the drier here.

Flip it from bucket to bucket

The easy way to get it consistent is to flip it into another bucket. Do this a couple times, allowing fifteen minutes for each flip.

All fluffed up

Fluff it all up and break up any final chunks. You can see it really expands in volume. Then I usually do the bucket flip thing once a day until it is half way dry again. Much easier to work with then and it won’t get that mildew smell.

Chunks and fibers

One thing I’ve noticed is that a lot of the longer “mattress fibers” are getting into the coir these days. This isn’t a problem when you planting up bigger plants, but they can be a pain when you are doing a seed flat. I’ve been sifting them out as shown below.

Sifting fibers

I used an old onion bag. Pack the coir in loose and shake the hell out of it. The “fines” end up in the bucket, the fibers stay in the mesh bag.

Years worth of mattress fibers

Here’s about a year’s worth of sifted fibers. As I said, I only sift out the long fibers when I’m planting seed flats, so not too much of a burden.

That’s it kids. Give this stuff a try, especially if you HATE peat moss. (I hate it!)

10 comments to Coconut Coir Tutorial

  • Corky

    Instead of the onion bags, what I use is an old metal coffee can with the bottom replaced by some quarter-inch screen. Toss in the coir, put the lid back on top, and then shake. Might be a little less awkward for people like me whose hands are getting a bit arthritic — and a coffee-can sieve has lots of other uses too.

    • Jason Moorehead

      Yeah that works. Now what we need is some mechanical advantage. My old friend Tom bolted a reciprocating saw to his soil screen. Just pile the dirt on top, turn the saw on, and it shakes itself. I’ve been thinking about it recently because I find myself sifting a lot of things lately: bark, perlite, coir….
      Thanks for visiting Corky.

  • mark clouse

    Reciprocating saws are cheap at Harbor Freight Tools – Google it.

  • Cindy

    I wish someone would sell this in a pure peat form with the long fibers already sifted out. I love to use it in my worm composting beds as bedding, but I too end up sifting out all the long strands. Unless I am using a horticultural/hydro grade I always soak it for 2 days and then triple rinse it just to be on the safe side with salinity.

    I know for a fact that peat moss has fungus gnat eggs in it. I don’t own any house plants so my house is gnat free. That is, up until I started growing all me vegetable starts indoors in spare room under grow lights. Gnats started hathcing out like crazy. I remembered reading somewhere that peat moss is a fungus gnat carrier but I wanted to know for sure. I had used an open bale in my garage so it was possible that gnats had found their way into it and laid eggs. So the following spring I decided to us a small bag of peat moss (like the type you find next to orchid potting mixes). This was a bag that had been sitting on a shelf unopened for at least five years. I couldn’t beleive it when gnats started hatching out again. Those pesky critters are difficult to get rid of in the house. Even if you remove every plant in the house, some will set up house in wet areas like sink drains. It took almost a year to get rid of them and that was only after I poured some Red Devil lye down every drain.

    I’m not completely convinced that coco peat is gnat free. I purchased some coco peat from a hydro store recently that has organically been treated for insects. BTW – this particular brand was buffered and this is something I try to do also. I add lime (calcium carbonate) to my soak water to raise the pH because coir can be very acidic.

  • Jason Moorehead

    When coir first came out, those bricks were pure fines and ready to go- zero long fiber and zero chunks. Now that it has become popular, I think the distributors are hustling to keep up with the demand, and thus we end up doing the sifting on our end. If you find a brand that is dependably fiber free, PLEASE let me know.

    Ah yes, the fungus gnat. As a proactive measure, try microwaving your peat/coir/starting mix. I use those plastic coffee cans: crack the lid so it doesn’t explode and go for about four minutes. It will be hot coming out so be careful. I shake it a bit and then turn the can upside down so the steam goes back through the soil. Keep turning and shaking every 5-10 minutes until it cools down.

    No matter what you use, those damn gnats will find their way into your soil at some point. Cisco used to recommend sand on top of the soil, but I don’t like what sand does to the hydrology of the pot. I use #2 chicken grit as a “mineral mulch” on top of all my house plants, and it may help deter the gnats to some degree. I’ve tried nematodes with some success, but the little buggers are expensive and I doubt they like it when I fertilize with the “blue stuff” plant food.

    The thing that really works is Gnatrol, which is a liquid suspension of Bacillus thuringiensis, subspecies israelensis (same stuff they use in “mosquito dunks”). I spent about $20 for a pint of the stuff, which sounds expensive until you realize I’ve used maybe half the bottle and I bought it at least five years ago. Whenever I get an outbreak, I let all the plants get good and dry. Then I mix the Gnatrol into the water, and water everything slowly and thoroughly so the stuff gets all through the pots. Bye bye gnat larvae. You’ll see a few adults for a day or two until they mate and die, but you will not see another hatch for months. This stuff has good residual effect, and it is completely harmless to you, your pets, and your plants. You could even mix up a batch and use that to rehydrate your coir (this might be the treatment used in the coir you bought). I do not endorse products, but then, B.T. var. israelensis is a naturally occurring organism, not a product, right?

  • Cindy


    I used to use Gnatrol until the price skyrocketed and then I switched to Mosquito Dunks and Bits. I floated the Dunks in my watering cans and put the bits in bottles of water and let them sit for several weeks then strain them to try and make a concentrated solution. Then a friend turned me onto MicrobeLift BMC Mosquito Control. It contains the same strain of BT as Gnatrol, B.T. var. israelensis, but it comes in a super concentrated form and is intened for use in ponds. My friend read about it on a gardening forum. It’s only a fraction of the cost of Gnatrol. A 1 oz. bottle goes a long, long way and will 250 gallons for 10 months. You only need a couple of drops per gallon. It is so highly concentrated that it has a thick syrup like consistency so if you add drops of it in its undiluted form directly into your watering can it sinks and doesn’t mix. So to get around this I mix up a small batch of dilute solution once or twice a month. I use a 6 oz squirt bottle and mix it with distilled water, then shake it until it is completely dissolved. This eliminates the problem.

    • Jason Moorehead

      Sounds good Cindy. I removed the link because I try and keep this site commercial free (unless I get paid) and because I haven’t tried it myself and therefore can not imply endorsement. For others reading this, yeah, why not give it a try? I probably will when I finally run out of Gnatrol. Definitely looks like a better deal.

  • boo

    Hi Jason,
    I live beside a beach on a tropical island 1/2 way between Australia and PNG. I picked up 25 gallons of seaweed and doz coconuts this morning to use in the school garden. I am interested in using coconut coir and coconut leaves and seaweed as a compost to condition the sandy soil. What are your thoughts?

  • Jason Moorehead

    Hi Boo,
    Why don’t you fly me in and I’ll give you a free consult! Then we can go on a botanical safari in PNG! I can leave right away, just send me a ticket.

    OK, seriously, Boo, there is a long history of using seaweed along the coastal communities of the world, building up those sandy soils with what is at hand. I just watched a program which featured a 90+ year old Newfoundland woman and she was putting a LOT of seaweed on her beds, every year, for decades, and she was getting some great crops. She’d pick up about as much as you could lift on a pitch fork, and put it on the garden, and she didn’t really spread it out, just got another fork full- that’s a good 10-11 inches thick. Sea weed is not as salty as people think- and sand has a very low CEC (cation exchange capacity) so any sodium is going to leach out fairly quickly, particularly if you have adequate potassium levels. Any carbon that you can get built up in the soil is going to have a positive effect on water and nutrient retention. Gather sea weed, coconut waste, fish carcasses, etc. and either compost them in the pile or dig them right in as a “sheet compost”.

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