Coconut husk chip "how to"

I have started using a coconut husk chip (CHC) based growing medium in many containers. I thought I'd post a little "how to" to encourage others to give it a try in the greenhouse or elsewhere.

Why? What's wrong with Promix or other peat-based growing media? The peat-based media work fine initially. But with time these mixes compact, leading to a high water table in the container, poor drainage and aeration, and root problems. A mix with larger particles solves that problem. Pine bark is often used for this purpose. But CHC has advantages over pine bark. It holds more water in each particle, yet it breaks down much more slowly. Pine bark has broken down substantially in as little as 6 months, yet CHC, because of the high lignin content, can hang around for as long as 7 years.

Why not? Cost. And you can't just dump this stuff out of a bag and throw it in a pot. It requires preparation.

Here is a Ficus 'Brown Turkey' that I potted into CHC about 8 weeks ago.

Here is a close up of the roots...nice white, healthy root tips...and pockets between the chips showing the excellent aeration of the medium.

I use a mix of small (1/4") and medium (1/2") chips. Here I am squeezing a single larger chip. See the water dripping out? I squeezed 45 drops of water out of this single chip.

The most important step in using CHC is the rinse procedure. Chips must be thoroughly rinsed. Some people mix large batches or bales in a wading pool. I use a pair of 5 gallon buckets. One bucket has holes drilled into the bottom to drain the water out. Here are two bricks in a bucket. The chips in brick form are compressed. They will expand greatly, as you will see.

Rats, got interrupted...to be continued...

ok so the bricks are about $ 4.5 each w/out shipping. It says they are prewashed-so do you still have to wash it? Do you mix it with a soiless medium like Pro-mix? How many gallon containers can you get out of each brick? If the husk holds that much water-are you ever worried about too wet a growing medium-or not because there is enough oxygen in there?? Whats the difference between this and coir? Coir is cheaper, is it too fine for the type of aeration that you are going for? With those huge air pockets-do you worry about liquid or slow release fert leaching out too fast?

lol I probably should have waited for the tutorial to finish...but its like being in the middle of watching a show and have it stop abruptly, and then just wonder what the end was going to be.

Hi TL, I will try to answer the questions by the end.

You should rinse the chips again anyway. I fill the bucket with water, then dump the whole thing into the bucket with the holes to drain. Rinse at least three times. Even after three rinses, there may be sodium in the chips. The sodium cation can occupy cation binding sites in the CHC and lead to deficiencies of other cations like calcium and magnesium. Therefore, in the last rinse, I add a tablespoon of Epsom salts (magnesium sulfate). This step is called cation exchange. Some people also add calcium nitrate at the same time, but I have lots of soluble calcium in my well water and I've never had trouble without the calcium nitrate. I have seen magnesium deficiency in my citrus without the Epsom salts in the final rinse.

Here are the chips in the final rinse.

Two bricks fill about 1/2 of the large bucket you see in the picture. One brick expands to 7 liters in volume. By the time you are done with the mix, two bricks make about 4.5-5 gallons of growing medium.

The rest is just mixing. I mix four parts CHC to 1-1.5 parts peat moss. Once this is mixed, to each cubic foot of the CHC/peat, I add 200g dolomite, 4 tsp Micromax for trace elements, and 8 tablespoons of 3-4 month 15-9-12 Osmocote with minors, and about 1T Miracid or water soluble fert for a little boost.

Coir is ground up CHC. I know some people experimenting with using coir in place of the peat. With peat, the pH comes in at 6.5 or maybe 6.75. With coir, the pH comes in closer to neutral, as I understand. You can't use coir in place of CHC, it is too fine.

I've heard of people using compost or rotted manure in place of the peat. I tried a 3:1:1 mix of CHC:peat:manure and it held way too much water...practically soggy.

The final mix drains exceptionally well. You have to be careful in repotting, because if the container is too big, water will just run down through the CHC and never wet the rootball of the plant. Plants require frequent watering at first, more frequent than with regular potting mixes. Once established, though, the watering is much less frequent. I water the plants in CHC less than half as often as other plants. The chips seem to just give up the water as needed by the plant. I have citrus in 3 gallon pots with CHC and even in this 90*F heat, they can easily go 3-4 days in the GH between waterings

I top off with a reduced dose of Osmacote every 3 or 4 months depending on the season and the plant's growth. Then about once a month I use Miracid or Miracle grow with a watering. Every other or every third watering I add some Epsom salts. Occasionally I'll use some soluble iron as well. Water soluble ferts are taken up by the chips. The Osmacote doesn't wash through, as you can see in the pic with the roots.

If you have used CHC, please post your experiences. If not, I would encourage you to give it a try!

SB

Edited to add that Nathan has kindly pointed out that more recent readings suggest that dolomite be added at a rate closer to around 50g/cu ft. My recent reading confirms this, and I have adjusted my recipe accordingly. Thank you Nathan.

This message was edited May 27, 2006 10:38 PM

This message was edited Feb 24, 2007 7:11 AM

I didn't know they were experimenting with the coir instead of peat....I know a PH dr here at NCSU that the canadian companies had hired to experiment with using coir instead of perlite because perlite is in such high demand for other uses, it is becoming cost prohibitive for the peat companies. They were looking at drainage, not water retention.
I think just plain peat comes in a lot lower on the PH scale-like in the 5's. Most soiless mixes contain a slow release lime charge to raise the PH to the low 6's. So I am thinking that I could use my soiless mix in your CHC mix and skip the lime.
I am torn between the pros and cons of the ability of the coconut husks that retain the water and reduce oxygen, but leave pockets of air for root growth-thus adding oxygen. Its interesting and I am thinking that it would be a good mix for these small palms that I just got it that will take a while to grow out.
You don;t think you have all the trace elements in the Osmocote ?You
have to use the Micromax? I don;t know anything about the Micromax-but what does it have that slow release ferts don't have?

If you add epsom salts every other watering -or thirdwatering-thats an application of magnesium every week or two? For all your plants? It seems like a lot of magnesium. How much do you add to the water? Are you watering with a gallon jug to apply it?

I've never played with coir. I think part of the purpose of the dolomite is to partially neutralized the lower pH of the peat.

The water is retained in the chip...kind of like a very stiff sponge. Despite the water retention, this is the lightest "fluffiest" mix I have worked with.

Excellent question about the trace elements. Micromax is a slow release (16-18 months, I think) trace element additive. I arrived at the amounts I use by looking at trace element concentrations in other mixes for citrus. The amounts of trace elements in the mix with only the Osmacote were a whole order of magnitude lower than in these other mixes.

Right now, for my citrus established in CHC, I'm watering about every 5 days or so. I don't use as much Epsom salts per gallon as others might, I put just 1/2 tsp or so in a gallon, so this time of year maybe every two to three weeks. Does that sound like too much? I have magnesium deficiencies in a couple of my citrus because I didn't add the Epsom salts to the CHC rinse when I started out. I've been trying to slowly correct that.

What is your soilless mix?

SB

I usually apply the magnesium once a crop-at a rate of 1 pound/100 gallons of water. If I have broken it down correctly thats 1 teaspoon/gallon for 5 months. Some crops-like the aloc/colocasias require more and I did it 3 times in 3 months-I could have done it more for them. One person said every two weeks. I could see doing it the amt that you are for specific plants that really benefit from it. Most annuals don't need anywhere near that much.
I use a soiless mix made by Berger -now I have to go-my brother is here to cut down some trees- will say more about the fert later

Here are some more pics. This is Satsuma with lots of new growth.

This is a Valencia orange in CHC.

A Radermachera I rescued from the office, cut back, and repotted into CHC.

I have experimented a little bit with the recipe. These two plants are easy to grow in about anything, I guess, but for now they are in the following mix:

25% CHC
25% Promix
25% well-rotted manure
25% turkey grit

I left out the Micromax and top dressed with a little Osmacote. Sanseveria...

...and one of about 6 Crassula, from cuttings.

Well, whatever you are doing, you should keep doing it! Those plants look to be in excellent shape. I think you are onto something with the regular soiless mix compacting over time and looking for a long term solution. Most of what I pot up is very short term and compacted medium is not a problem-but like I said above, I have over 20 palms that I will be growing out for a few years.

Now tell us about turkey grit and where do you find these ideas???

Here is a pic of a handful of rinsed CHC and a handful of turkey grit.

I should have put something as a size reference. Pencil added...

I saw a picture of the turkey grit on taplas answer to yr question in cont. gardening. His looks even courser than yours....it looks like gravel. Is that all that it is? Is the drainage/compaction problem that severe that you would combine the husks and the grit? That seems like a lot of aeration in your pots.

Meant to say thanks for posting these threads and making us think in new directions-was thinking about this while I was just planting a flower bed.

I don't remember where I got the turkey grit idea, but it works...maybe it was Al! The key is in providing long-lasting structure to the growing medium. This assures healthy root aeration. Sand might work just as well, maybe even a little better for little guys like the Crassula above. I'm always fooling around with different mixes...got some charcoal to try next... ;-)

TL, you hit upon an important point, and I probably should have mentioned this in the very beginning. CHC is not for every pot or plant. Annuals planted out each spring and dumped out in the fall won't do any better with CHC...maybe worse. It is too expensive and the prep is too time consuming to use for this application. You are right, over this period of time, the compaction problems with a peat-based medium will not have time to develop.

But CHC may be ideal for your palms that you expect to have around for many years. Smaller plants may be potted in small (1/4") CHC but then you can move up to a mix of small and medium or just straight medium chips.

I think that Tapla "Water Movement in Containers" post is one of the most informative things I have read, and it ought to be required reading for anyone who grow plants in containers!

I actually did his wick experiment on Promix versus CHC. There is essentially no perched water table in the CHC medium I described above.

You should post this thread over on the container gardening forum as well.

Didn't have time to finish about my soiless mix before... it is 80% peat and 20% verm and perlite, with a small amt of booster fert and a slow release lime charge added. For annual crops its fine, but you are right, I need to be adding something like coco. chips to it for long term. Am also going to check out the Micromax......anything for my palms lol

I use CHC with all my orchids. It has improves the roots because it gets them to reach for the moisture inside the chips. It also sits in the containers loosely which provides air to the roots. Even when I was bad and hadn't watered my orchids for weeks at a time in the winter, indoors, not even in a greenhouse, the chips stayed moist. I make sure to soak and rinse twice with the chips.

I have excellent results growing seed in coir and propagating in coir. It has the same benefits as the chc but I could see the coir being loosened up a bit. It's a little looser than ordinary potting soil even.

The only problems I've had with coir is when the seedlings start needing nutrients. From reading this thread, I've found out that I should use fertilizer at a diluted rate and add epsom salt.

Thanks for your input, Captain. Your experience mirrors mine with other plants.

From what I can tell, orchid growers are the ones who first popularized CHC as a growing medium. This link has some very interesting graphs comparing CHC and pine bark: http://www.ladyslipper.com/coco3.htm

Yup, that's the site I used when I was considering CHC. I also use Dyna-roks in med. size just for a little bit extra moisture. Plus, they're pretty.

Stressbaby --- do your CHC mixes eliminate or minimize the the perched water table (PWT) problem that tapla discusses in his postings on the Container Gardening forum? Or do you still have to install wicks in the bottoms of your pots?

Whoops - never mind. I just reread this thread and saw that you answered my question in one of your May 29 postings.

This message was edited Jun 2, 2006 1:18 PM

I copied my experiment from the other thread:

I set up four 1 gallon pots, two with Promix (standard potting soil out of the bag) and two with CHC:peat 4:1.5 ratio. I'll measure the difference in weight between the pot saturated just after watering and the weight 16 hours later, with and without a wick, in each growing media. The difference between the decrease in weight without a wick and the decrease in weight with a wick should represent the amount of water the wick effectively removed from the PWT.

For the saturated figure (weight immediately after watering), I averaged two measurements.

Promix without wick
Saturated 1458g
16 hours later 1318g
Drainage 140g (140ml)

Promix with wick
Saturated 1525g
16 hours later 1322g
Drainage 203g (203ml)

Therefore the wick effectively removed 63ml of water from the PWT of a 1 gallon pot in 16 hours.

CHC without wick
Saturated 1183g
16 hours later 1068g
Drainage 115g (115ml)

CHC with wick
Saturated 1109g
16 hours later 992g
Drainage 117g (117ml)

The wick had virtually no effect on the CHC. Presumable this is because the larger particle size in the CHC lowers the PWT to a negligible level.

Very interesting thread. I have previously avoided CHC because of lack of availability and concerns about residual salts and cation binding. I do successive soaks and rinses with my coir and count on the dolomite to provide more available calcium and magnesium, but I hadn't considered soaking in magnesium salts.

I recently cancelled my order for coir after it was delayed 6(!) months from my supplier, so I'm going to need to purchase an ammendment someplace else soon. Where can I find CHC?

I googled it and found quite a few suppliers, and the price really varied amonst them.

Until I get mine in, I am using as fine a pine bark mulch as I can get and mixing it with some promix. I was just at a big palm grower's nursery and he was telling me that he grows in straight pine bark mulch-he doesn't like the peatmoss mixes at all

I know of an ebay seller if any one wants the name. She's my supplier. You're gonna have to email me for it, I don't think I should post it here.

CaptMicha, is she less expensive than the garden/grhouse suppliers on the web? If so, would you mind dmailing me with her name? Thanks

I'm getting itchie to get my new greenhouse up and out of the boxes and was poking around here in the Greenhouse Forum and lookie what I found! Great thread! Great photos! The url to this thread goes into my Journal with the few other insturctional threads that I need to refer back to from time to time. Thank you stressbaby!

Robert's Flower Supply http://www.orchidmix.com/ is the only place I've found to get this in bales besides calling up the Crystal Company. If you have another source for more than a cu ft. at a time, I'd love to get it from you. There doesn't seem to be a source in WA, either.

How can you tell if a plant has magnesium defiency?

You walk up to the plant and politely ask it if it feels Mg deficient. Just teasing with you.

Generally there are initial signs in that the plant will begin losing its nice green color. The leaves start turning yellow. Many reasons for MG deficiency but interestingly enough, too high of potassium levels is one of them. Potassium suppresses a plant's ability to uptake Mg. Sometimes root systems fail because of the soil.

If you are concerned, have your soil tested or try a little foliar feeding of the plant you suspect is Mg deficient and if it improves, continue to fertilize it with magnesium sulphate.

Mg deficiency in citrus gives a unique inverted "V" discoloration in the leaves. It looks like nothing else and it is easy to diagnose.

SB

Does that apply to Gardenias too? I have the worst time with them...I know they like acidic soils

I keep losing leaves on tropical hibiscus. And the bottom leaves of my seedling milkweeds but I gave the milkweed epsom salt.

Does anyone know if aquarium salt is the same as epsom salt?

Not usually. "Aquarium salt" is usually a blend of calcium and sodium salts, with magnesium tagging along, as it often does, with the calcium. The two principle kinds that I've used are the freshwater additive, which softens the water for goldfish and the like (mostly sodium) and the "instant seawater" which tries to reproduce ocean water for my saltwater tanks. Neither is very good for plants.

Of course, I depend on dolomite pretty heavily for magnesium supplementation in the soils I mix. The heavy organic bases I use tend to need ph adjustment anyway.

Where do you buy CHC? I saw this on ebay: http://cgi.ebay.com/Coconut-Husk-Chips-CHC-Orchid-Potting-Medium_W0QQitemZ170028071560QQihZ007QQcategoryZ42218QQssPageNameZWD1VQQrdZ1QQcmdZViewItem. Is this the same stuff? What about turkey grit -- where do you buy it? And what is a reasonable price for CHC and turkey grit -- not to mention all the other additives that have been suggested? This is all very tantalizing, but I wouldn't know where to start!