Ask Ed's Coco Coir Guide
By AskEd
What is coco coir?
Coco coir is the fiberous strands found between the coconut and husk, it’s a by-product of processing coconuts and has recently become available for home gardeners. A lot of people are discovering what a quality growing medium it is and as more people use it, more stores will stock it!
Coco looks just like a high grade soil, and comes in bags (ready to use) and very commonly as compressed bricks that expand when water is added (very convenient for shipping).
Many types of coco are available now, coir, bricks, croutons, mats, soiless mixes, etc.
Sri Lanka & The Philippines are major producers of coconut coir. India is the world's largest, but they export very little.
Coco and the Environment
Coco coir is a by-product of the coconut harvest. It can turn into waste or high quality growing medium. It’s a no brainer as to the benefits. That’s only half the story though.
Coco serves as a replacement for peat. If you are not aware of the effects of harvesting peat from bogs, please do a quick search (after reading this of course) and it won’t take long to see using an alternative is good for the environment. Not only does coco replace the need for peat, but performs better.
Is Coco Hydro or Soil?
It’s actually “Soiless”, which is like a hybrid of both and needs to be treated like hydro, even though it looks like soil. Use quality hydro or coco specific nutrients and ph to 5.8, and water as if it were soil. You’ll have to feed every water cycle or alternate between the two since coco is an inert medium. Growth for coco is faster than soil, but less than or equal to hydro setups. We’ll get into this some more, but for now we just want to clear up that hydro-soil thing.
How to Grow With Coco
The cool thing about coco is it can work with a variety of grow styles with impressive results. For this guide we will focus on good ol’ hand watering, just like you would using soil. A good mix is equal parts coco & perlite, I’ve had the best growth rates with this ratio. The down fall is that it will require more frequent watering since it’s such an airy mix. I normally use roughly 75% coco & 25% perlite for mixes, it’s a great ratio and performs very well.
Coco performs well by itself and is very forgiving about watering. I have tried and failed to overwater plants in 100% coco. To me they seem to grow a bit slower without perlite.
It should be noted that coco works exceptionally well with drip and wick type setups. Coco can be used with flood tables but the cycles should be short and reduced to once or twice a day at most. I’ve seen a flood setup cycling every-other day with fantastic growth. There are coco cubes available now that you can use in place of rockwool as well. Coco rarely grows algae.
Again, for this guide we will concentrate on hand watering method.
Preparing to Grow With Coco
Coco requires a hydro way of thinking, which is weird when it looks and acts like soil. With that said, your basic grow kit is exactly the same as a hydro setup. Ph is everything, you can go without a TDS or EC meter, but a good PH meter is a requirement, no excuses! Budget at a minimum $40-$100 dollars, I don’t want to hear any bitching about how it’s not within reason, paying lots of money for a gram of weed is not within reason. With the meter you also need some calibration/storage solution. Meters need to be checked monthly at least. Don’t skimp out on ph in any way, it’s the last thing you check when feeding, and the first thing you check when there’s a problem.
Coco Nutrients
There are a lot of coco specific nutrients out there and I highly recommend them for ease, but beware as some can be a bit pricey. However you can use any hydroponic nutrients. If you are not using coco specific nutrients then you will need to use CalMag or Epsom salt or some equivalent supplement to correct the calcium issue that coco has, especially if you are using purified or distilled water. Just follow the directions on the bottle and add every time you use nutrients.
Watering Coco
There seems to be a bit of confusion when it comes to watering coco, even intimidating depending on who you listen to. I’m here to tell you it’s very simple. First off, use light pots, don’t get some heavy material container, plain plastic works great, buckets or bags work well, smart pots are fine too. If you lift the pot you can tell if it needs watering by how light it is. Learn to judge the halfway weight by feel, when the pot feels less than half full, water it. Try this lift technique for two weeks checking daily. You’ll be a pro at the end of that two weeks.
This of course presents a problem when using a screen. When designing a scrog setup, keep in mind you will need to flush while the plant is in place, and normally you can lift it enough to feel the weight without too much trouble.
Indoors, normally plants can go 1-3 days between waterings in 1 to 5 gallon containers. Young plants may go 5 to 7 days between waterings. 10 to 15 gallon containers may go 10 to 14 days. Outside grows may require a more frequent schedule, more so than soil and even more so if you mix in perlite. Once flowering begins, the water consumption will increase and you may be watering daily when you factor in the size of the plant and container size. This may sound a lot like a soil schedule, and that’s just about right. Trying to schedule waterings of more than one plant can get complicated if you’re using the last day as a calculation. That’s why using the lift method is so handy. After some time you can forecast up to 2 or 3 days of when a plant will need watering next with a simple 2 second lift.
Give enough water to see some runoff or almost see it, especially when nutes are mixed in. Runoff with plain water means you’re washing out nutrients, coco is very easily flushed.
Watering Coco With Nutrients
Just like soil, you feed the medium, and the medium feeds the plant. Coco does not have nutrients like soil, so when your plant enters the veg stage (when you see the 3rd set of leaves), it’s time to feed.
How often to feed is something you will have to figure out, there’s no one way for anyone to tell you and this is where a little grow experience is very helpful. Factors like strain, lighting, pot size, amendments, can all affect your feed schedule. The best approach I can offer is to use a very basic baseline and adjust as needed, or follow the directions for your nutrients at a lower dosage and increase as you see fit. I’ve yet to use any bottled nutrients at instructed full strength that didn’t burn.
A generic baseline approach would be the same as hydro. Just like in a DWC setup, start feeding around two weeks after sprout with about 150-300ppm. Do this every-other watering and watch your plant. If she looks hungry, try feeding nutes-nutes-water. If she looks over feed try nutes-water-water. You get the idea. You have to dial it in, and every plant you grow may be different. Increase to 400-600ppm after a few weeks, then eventually up to 800-1000ppm. I rarely go over 900ppm. Coco likes frequent low does feedings, but you can hit them hard when needed. If you over do it a flush should get you back in good shape.
This may sound a bit difficult, but it’s not as bad as it sounds, especially once you get a few weeks under your belt. Coco can absorb and release nutrients very quickly, like a broadband internet connection. This is one reason plants grow so well in coco, the high CEC ratio makes plenty of food available to the plant when it wants it.
I highly suggest keeping a feeding & watering log. This is a tremendous help when trying to troubleshoot or determine if you need to feed or not. Beginner growers should really stick to one strain at a time as opposed to trying to grow different strains at the same time. Having all your plants on the same schedule is a blessing, take advantage if you can.
PH and Coco
Most coco comes out of the bag at 5.5 – 6.5, this is great for weed! When you water or feed your plants, make sure to ph to 5.8. Coco is very forgiving either way, but growth really slows over 6.5.
Coco Problems
There can be no Heaven without Hell, so let’s look at problems to watch out for with coco. First let me say, the problems are minor and easily fixed. And while not necessarily a problem, I should mention that coco can be a little on the expensive side. Personally I don't think it's a big deal, but thought I'd mention it just the same. I don't think it's any more expensive than good soil to be honest. Besides, money is like the wind, you only feel it when it's moving.
Calcium – The only real issue I’ve ever experienced in all my coco grows is calcium deficiency. This is a well documented trait of coco, it tends to absorb it and not release it in the quantity the plant needs. Many coco specific nutrients claim that their product corrects this, and I believe some do. But I can tell you not all of them do.
To correct the issue, whether using coco specific nutes or standard hydro nutes, supplemental calcium is needed. Botanicare CalMag is a very common and recommended fix. It works well but some heavy feeding plants hitting their stride, even twice the dosage may not be enough. This has happened to me on many occasions. The one thing I’ve found that works very well is adding dolomite limestone to my coco medium at the rate of 1 tbsp per gallon of medium. Hydrated lime also works very well, and needs to be applied every 4 to 5 weeks as a top dressing.
Once a calcium deficiency starts, it will continue to deteriorate even after a fix has been applied. It’s an extremely frustrating ordeal and can trick you into taking drastic actions because nothing seems to be working. If you stay calm, you’ll find that it really doesn’t affect much other than making your leaves look like crap and killing them. Buds seem to be unaffected for the most part.
Calcium deficiency is more of a pain in the ass than problem, but it usually starts with little rust spots.
Magnesium - Heavy feeders seem to use up a lot of magnesium in coco, even medium feeders can consume quite a bit if they hit a growth spurt. If you notice a deficiency, treat it quickly with some CalMag (5-10 ml per gallon) or epsom salt (1-4 tsp per gallon). When treating a deficiency, hit 'em hard with the first application, then lower the dosage by 1/2 for the next few feedings.
Magnesium deficiencies normally start in the lower leaves. The veins remain green while the rest of leaf turns yellow and shows chlorosis. The leaves eventually curl up and die. The edges of affected leaves feel dry and crispy. As the deficiency continues it moves from lower leaves to the middle and upper half. Eventually the growing shoots change from pale green to white color. The stems and petioles may take on a purple color.
I haven't had a lot of mag problems, but I have always supplemented with CalMag or epsom salt. I use RO water and add 1 tsp epsom per gallon. This is something to watch out for, and I suggest always supplementing your water (even plain) and nutes. If you are flushing like you should, you should not have to worry about salt buildup.
Magnesium deficiencies can show their ugly face in a number of ways, this is the most common. Note the taco curling on the upper leaves, lack of magnesium can cause this.
Salt Buildup – Coco retains salt, and since most chemical nutes are derived from mineral salts, they leave salt deposits behind in the coco when the roots suck up the juices. Those salts cause all kinds of havoc on the leaves because they make the ph swing when water passes through the medium. Just like soil LOL
The good news is that coco flushes twice as easily as soil. Flush every 4 weeks as a rule of thumb and you should not have any problems. Use 2 gallons for every gallon of pot size. So a 3 gallon pot needs 6 gallons poured through it. Ph your last gallon or two.
Benefits of Using Coco
Hard to overwater - One of the most impressive attributes of coconut coir as a growing medium is the level of aeration and structure supplied to the rootzone. Coco is difficult to over water. Basically, if you supply too much water it will just run out the bottom of the container, and will not become water logged (anaerobic). The coconut fibers are much tougher and coarser than those of peat for example. This means more airspace is available for drainage and to supply the roots and soil life with more air.
Coir fiber will not compact over the course of the grow. You may have experienced filling the pot right to the top with peat at the start of the grow, only to find that a third of the media is “gone” by harvest. What is happening is that the peat fibers are eroding from the force of watering, saline conditions, and the roots compacting the media. This robs the crop of valuable air space in the rootzone, and increases salt build-up as drainage is impeded. With coir fiber there is little if any compaction of the growing media over the cropping cycle due to the higher content of lignins and cellulose found in the physically coarser fibers. In container grown crops, little compaction is evident. Plants receive optimal water to air ratios over the course of the entire crop, not just the first few weeks.
Fewer pests! - I have a curse with spider mites whenever using soil indoors. You have a lot less chance of that with coco, including most other soil pests. You're not immune, just safer is all.
Impressive Growth - The most common comment I hear from coco growers is the fantastic growth rate. There are several reasons for this, and the accumulative effect is vigorous plants and large buds.
