How to Prepare and Buffer Coco Coir

Prepare the Best Coco for Cannabis

Choosing a Brick?

When purchasing new coco coir, you have many options. You can get an inexpensive brick of dehydrated coco, or a relatively expensive, already prepared product. See our Equipment and Product Guide for our specific recommendations for each. If you opt for a prepared product you can skip the steps for rehydrating, rinsing, and buffering and simply add your perlite. If you opt for a brick, you will need to follow all of the instructions below. In either case, the quality of the final product will be the same. Purchasing a prepared product is like hiring someone to do the rinsing and buffering for you.

Rehydrate, Rinse, Buffer, and Mix

Overview of the Process

To Prepare Brick Coco:

  1. Re-hydrate in tap water
  2. Rinse through a screen to remove coco peat (dust size particles). This also starts to remove sodium. Use a 1/8” mesh screen or a perforated strainer. (See video)
  3. Buffer rinsed Coco in Cal/Mag

To Buffer Coco:

  1. Prepare buffering solution: Tap water with full dose of Cal/Mag (150% dose is fine. I use 7.5ml/gal of “CALiMAGic "
  2. Place Coco in a fabric pot - and then place that into a bucket.
  3. Soak Coco in buffering solution for 8+ hours
  4. Raise fabric pot and allow to drain - dump bucket
  5. Soak again in fresh buffering solution for 8+ hours
  6. Drain and it is ready to be mixed with perlite

Understanding Coco

There are many reasons that coco is a superior growing medium: it has excellent water retention and drainage properties, is pest resistant, offers abundant root space, and, if buffered, it will not interfere with plant nutrition. These features of coco enable the style of high frequency fertigation that we recommend.

However, if you purchase a brick of coco and you do not rinse and buffer it, you are not growing in a superior medium. Un-rinsed coco is laden with “coco peat”, which are small dust sized particles. The coco peat does not retain air like the larger coco fibers do and as a result, you can run into problems with drowning your roots if you grow in coco with a lot of coco peat.

Buffering is an even larger issue! Coco must be buffered with calcium (Ca) and Magnesium (Mg) before it becomes a superior growing media.

Why You Need to Buffer Coco

There are cation exchange sites in coco that will interfere with nutrition until they are buffered. The cation exchange sites in coco naturally come loaded with sodium (Na) and potassium (K) cations. However, the Na and the K are only weakly held to the exchange sites. In the presence of calcium (Ca) or magnesium (Mg), the sites will release their Na or K cations and lock onto the Ca or Mg. These processes are known as “cation exchanges”.

Buffering coco is accomplished by presoaking it in Ca and Mg to allow the cation exchanges to take place prior to adding plants. Simply soak your coco in a solution of Cal/Mag water and the exchange sites will release their K and Na cations and lock onto the Ca and Mg. When the cation exchange sites are loaded with Ca and Mg rather than Na and K, it is “buffered”. The bonds that hold the Ca and Mg to the sites are very strong and cation exchange will largely stop. This means that all of the nutrients that you add to the water will be available to the plant at the ratios that you provide them.

Many growers are unaware of the need to buffer the coco and they try to grow plants in unbuffered coco. In unbuffered coco, the cation exchange sites will strip the nutrient solution of the Ca and Mg and replace those cations with Na and K. This creates a sub-optimal Nutrient Element Ratio (NER) and renders Ca and Mg unavailable to the plant.

Failing to buffer the coco is why so many growers suffer calcium deficiencies in coco grows. Sometimes plants can be salvaged with heavy applications of Cal/Mag supplements, but this dramatically slows down growth. Manufacturers of prepared coco products try to exploit these problems and convince growers that only their proprietary products are suitable for growing. However, it is actually very simple to properly buffer your coco yourself. This tutorial walks you through the process and provides all the information you need to turn even the cheapest brick of dehydrated coco into a superior growing medium.

Preparing and Buffering Your Coco

Rehydrate and Rinse

When starting with a dehydrated brick of coco, it should first be rehydrated in tap water. Rehydration is fast as coco loves to absorb water. The slurry that is produced should then be rinsed over a screen to remove the finest coco particles, known as “coco peat”, which retain too much water. Your goal at this stage is ending up with larger coco fibers. Use a 1/8” mesh screen or a perforated strainer (See video).

Buffer Coco to Satisfy the Cation Exchange Sites

Rinsed coco should be buffered prior to first use. I recommend double buffering to ensure that the cation exchange sites are fully satisfied with Ca and Mg. Once it is buffered, cation exchange will no longer interfere with your grow and the plants will take nutrition (including Ca and Mg) directly from the nutrient solution.

To Double-Buffer Coco:
  1. Prepare buffering solution: tap water with 150% dose of Cal Mag supplement (=7.5ml/gal of General Hydroponics “CALiMAGic
  2. Place coco in a fabric pot - and then place that into a bucket
  3. Soak coco completely submerged in buffering solution for 8+ hours
  4. Raise fabric pot and allow to drain - dump bucket
  5. Soak again completely submerged in fresh buffering solution for 8+ hours
  6. Drain and it is ready to be mixed with perlite

Mix Coco with Perlite

Perlite dramatically improves water drainage and aeration in coco. Mixing perlite at the ratios given in the chart below makes it very difficult (but not impossible) to overwater. Also, since it improves water flow through the medium it improves the flushing of unwanted salts. Coco without perlite does not drain as well. However, in small containers, drainage is better, and you can reduce the perlite percentage to increase root space. When following a transplant strategy, perlite percentage should be mixed at ratios needed for final containers.

Container Size Quantity of Media Perlite % Perlite Volume Coco Dry Weight
2-gallon 2 gallons 0-20% 0-1 quart 450g
3-gallon 3 gallons 30% 2 quarts 550g
5-gallon 4.0 gallons 40% 4 quarts 650g
7-gallon 5.5 gallons 50% 6 quarts 800g
10-gallon 8 gallons 50% 9 quarts 1250g
Once buffered and mixed with perlite, coco is an unbeatable grow medium for cannabis!

Have Questions, Comments, or want to Discuss? Join us in our Grower's Forum!

Author: Dr Coco

I am a university professor and have taught courses in horticulture. I am coco for cannabis and I hope you are coco for cannabis too :) Grower Love!

36 thoughts on “How to Prepare and Buffer Coco Coir

  1. Hey man love the video great content! I was doing it wrong haha. I rehydrated a brick a while back to mix it with my soil. I never rinsed it to get the crap out of it! Do you think since I didn’t rinse it I maybe shouldn’t put my plants in there? It might be hard to rinse it now tho it’s mixed in with dirt. I was thinking I should just start fresh what would you do?

    1. Hey Scott! Thanks for the comment.
      You can get away without rinsing, especially when mixed with soil. Something to remember for next time, but not worth dumping the media and starting over.
      Did you buffer the coco with Cal/Mag? That is the more important consideration – and can still be rectified. I would follow the same buffering process with the soil/coco mix.

      1. Lol actually I didn’t and it’s mixed with super soil right now so maybe it would be ok? The super soil is blue sky organics and apparently it has alot of calmg in it already! But I won’t be using this dirt again it’s to expensive and you still need to add nutes. I thought I could get away without haha. 1st time grower here!

        1. Yeah, I think fertigation is more efficient (adding all nutrients to the water). Especially if you need to add some.
          How much coco is mixed in with the soil? The coco itself will take a large portion of the available Ca and Mg. You should be on the lookout for Ca deficiency and start adding cal/mag if it appears. I would not try to buffer the mixture as that will strip a lot of the nutrients out of the soil.

          1. Yes!
            Rinsing it improves the quality. It is not mandatory, but it makes the coco better.
            Buffering is pretty mandatory. Unbuffered coco will strip a lot of Ca and Mg out of the solution and make it tough to get any to the plant. With only 20-30% coco in a mix that is high in Ca and Mg you will be able to manage, but I would have some Cal/mag on hand because I suspect that you may need to add some.

          2. Thank you so much man I feel like a just leveled up at growing haha! I do love to grow in dirt so I do have the general organics line of nutrients. Am I able to buffer the coco with this version of calmg? And one more question is it possible to use this line when growing in 100% coco?

        2. Yes, and in fact I am planning to run my next grow with organic fertigation! There is no problem with buffering the media with organic sources of Ca and Mg. In 10o% coco (I actually rec some % of perlite – but no soil) you can fertigate with any nutrients that are water soluble. The issue becomes how long the nutrient solution is good for. With some organic nutrients it is only good for 24 hours, which makes running a drip system tougher, but not impossible.

          My Organic grow will start sometime in December. I will certainly keep everyone posted and hope that others will want to grow along with me!

          1. That will be awesome 🙂 can’t wait to see how that goes for you and I wish you luck! Just curious do you know what organic line you were gonna choose?

          2. I haven’t done all of my research into the different options yet, but General Organics is certainly a contender. I think you will have no problems with it. I hope that you start a grow journal in our forum! I will follow along and perhaps that will convince me!

  2. I definitely will consider that 🙂 I’m only 2 weeks in on these little guys and they are just in pure plain dirt in a 4″ peat pot so it’s not to late to start. 😀 hey I was actually trying to DM you because I had a few separate questions for you (I hope that’s ok with you!) But when I clicked on private msg it just takes me to my own profile haha

    1. You can ask me anything you want in any channel that you find!
      We are still considering the set-up of the various social network functions on the site. Right now we are using one platform for the forum and a different one for messaging, but it is awkward so we may change. In the mean time, on the top bar you should see “Howdy, Scott” if you hover there a menu will appear with a “messages” option.

      You can also start a thread to ask your questions in the forum. Or just post them here!
      We will continue to work to improve the functionality of all of this.

  3. its all good i honestly just think its cool to be apart of this at such an early stage! i didnt realize you guys were just starting out until this morning haha. i must say your doing a wicked job so far 🙂 and ill actually start a thread or 2 so i dont have a bunch of unrelated questions on here haha

    1. Thanks!
      We are happy to have you on board!
      The site launched on Sept. 1. The forum just launched 24 hours ago! Really appreciate the compliment and we will continue to develop all the resources here over the coming days-weeks-months.

  4. Heyo. Sorry I’ve got like a million questions! Haha. I just rinsed my coco and noticed that there are alot of salt granuals in it. I didn’t get alot of them out during the rinse and there’s also little white chunks everywhere. Should I be concerned? Or was the rinse mostly for the peat dust?

    1. Yeah, there is often sand and other impurities in brick coco. I have certainly seen the mysterious white chunks too. I originally thought they were salt, but appear to be some other impurity. I haven’t had a problem when a little gets left in the coco. The peat, sand, and other impurities are largely removed when rinsing, but you don’t need to make it totally perfect. It is just a step to improve the quality. Many growers do not rinse their coco at all and still manage, so having rinsed, your coco is better than most!
      I wish I had experience with the EC of the General Organics feed schedule. Without specific knowledge, and since you are not measuring EC, I would be cautious and probably cut the doses in half. My feed schedule is about half what GH recommends for the Flora series, but I am adding Cal/Mag – which raises EC.

  5. I’m really leaning towards measuring the ec at this point. I originally said I wasn’t going to because I was having a hard time grasping the topic and I didn’t want things to get to complicated. But after learning so much I have a good understanding of ec and it isn’t a bunch of jiberish to me anymore!
    If I do start you will see it in my grow journal 😎

    1. Great to hear for both reasons! 1) that you understand it now from reading the articles here! and 2) that you are going to measure it.
      Measuring EC really lets you be in control of fertigation. It is critical info and having it you can run the perfect EC. Without it, you would have to play safe and stay at lower doses, so it is an excellent (small) investment!

  6. Yo dr coco! I don’t understand your math behind the coco/perlite ratios. Wouldnt 2 quarts be 16% of 3 gallons? I thought I was good at math but maybe I’m in for a lesson lol. I’m still gonna put the amounts you say in but I’m just a little confused at the chart!

    1. Your math is fine!
      The ratio is by dry uncompressed volume. That would be clearer in the chart if I listed the dry volume of coco, but I describe the quantity of dry coco by weight because it is easier to measure. Also since most growers use compressed bricks, there is no good way to even recreate “dry uncompressed volume”.
      Coco expands significantly when re-hydrated which along with air space accounts for your ability to create 5.5 gallons of media with only 6 quarts of perlite and 6 quarts of coco (50%).
      It is not an exact science because all coco is a little different. But that is fine, because you don’t have to be super precise with the ratio.

    1. Just follow the recipes and you will be fine!
      If you already have Wet coco (Canna comes dry, but uncompressed), but if it is wet, just do it by container volume. Depending on your container – make sure it includes the amount of perlite listed above. You may be over-thinking! But the first question was a good one – I had been expecting someone to ask why the math doesn’t seem to work! Grower Love!

  7. Hi,good to be here. Im growing in 50/50 coco/pebbles.I read your artical about treating the coconut with Cal Mag.I only have access to a three part feed that is not coco specific, i also didnt treat the coco as like you said ,the bag said added microbes etc ,so thought it was ok to use. The Gellato plants are in there 4 fourth week,im running 1100 ppt with base well water of 300. Hard water. How much Cal Mag would i have to add to try and correct this problem before i can get coco feed? If i supply some cal mag,what ppt should i add?If its not to late,i hope you can help.Bye the way,anyone thinking why cant i go to shop and bye,its because theirs only one outlet on this island its a very long way.

    1. Hey @sativafiend Welcome to CocoforCannabis! I want to invite you to our forum (link in top menu bar). It is a great place to ask questions and chat about your grow!

      First, Are the plants having problems?
      2nd, What kind of coco did you start with? Was it a dehydrated brick or did it come sort of loose in a bag? Was there a brand?
      3rd, do you have CalMag now? If so, the maximum dose of CalMag should be EC 1000 (500PPM).

      However, before I advise you on a course of action, I need to know the answers to those questions. Come to the forum and start a thread there so we can discuss!

      1. Hi Doc. I will start on new thread in forum next time,still finding my way around. I used top crop coco,not brick.I do have some cal mg from Atami left.Im using three part PH perfect from AN ,B52 and Sensizyme. i have some epsom salts also for Mg ,if it would help.The plants are growing fast but i noticed some twisting on newer upper leaves. My pump comes on every three hours in light on period,for 15 mins. Temps,water 22c ,air 27c, in a recirculating system.They are 11 litre pots .There is healthy root growth coming out of pots. I have seen a few fungus gnats and sprinkled DM earth over the surface of coco,hoping this helps.

        1. Cool, I saw and commented on your forum threads already. It is fine to post comments/questions here too, but easier for me to find them quickly in the forum 😉
          I think the coco you are using is pre-buffered, but still requires a dose of cal/mag in the nutrient solution. This is especially true now. You may reduce CalMag as they grow into late veg and flowering, but still need some. I have some Qs, but I’ll ask in the forum threads.

  8. I’m gearing up for my first time grow in Coco and I recently purchased a 50 liter bag of what’s advertised as “pre rinsed” and “buffered”. My question is, should I take their word for it, or would it be ok to rinse and buffer the bagged stuff as recommended above? If it’s already been buffered can I overdo it by buffering it with CalMag again?

    1. Hey Ron,
      There are many good prepared coco products and generally I do take their word when they say it is buffered. However, there is no risk of “over-buffering”, you can go ahead and rinse and or buffer the coco again. Thanks for the question! Happy growing! and I hope to see you stop by our forum!

  9. Hi Dr. Coco, I just want to say thank you so much for giving us all the outstanding info. and expertise about growing in coco. I never grew in coco before or used GHs Flora Trio, I bought a bunch of compressed coir bricks, 2 large bags of perlite, and the Flora Trio, and a bottle of calmag. I followed your instructions on washing and buffering the coir and added your recommendations of the amount of perlite to 5ea. 5 gal. Smart pots, and also sprouted in Rapid Rooters which I never used before either. I planted 4 Black berry kush, and one Cheese. Today is week 2 and the girls are 3 inches tall with thick stalks and leaves wider than I’ve ever seen. I contribute this fantastic start to you and your instructions. I’m really amazed at the quickness of the grow, and the leaves are so nice and dark green. The only thing that I’m doing that’s a bit different is I’m feeding them with a regiment called the Lucas formula made for GHs Flora Trio, they( the plants) seem to like it. Sorry for the rambling on but I’m so happy I tried coco your way. Oh and also I’m using a single 315watt cmh with a Philips 4200k Master grow bulb at 24″ above the plants. Your info. is the tops…

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