Its pretty long but it helped me.
The last paragraph is of particular interest.
Growing on Coco: Busting the Myth
by Ralph B. Par
The Indoor Gardener Magazine Volume 3 - Issue 6
Coconut peat has some wonderful physical properties that greatly benefit plant growth. To begin, it is renewable - no stripping of nature's resources. It makes use of the final product left over from cultivating and harvesting the much-prized nut. At the right point in its decomposition, coco peat can be used as a stand-alone medium with no need to add perlite or other persistent amendments. Coco peat itself is fairly pH-stable and buffers the pH well, in a very acceptable range for plant growth. WHile they are fairly solid and big early on, once the peat particles are treated and decomposed to a certain point, they are like sponges with micro-pores that hold water, away form the plant roots but available to replenish the larger pores the plant root can access. This effectively limits excess water while retaining water reserves. These particles hold onto no ions, only what may fill and dry on the particles themselves. So as long as the medium is moist , nutrients are available. At the proper point of decomposition, the particles form the perfect combination of air-to-water, because of the different fractions now present, which can actually mean more air space to water pace, with the micro-pores holding a reserve of water, giving a nice water buffer. Unlike peat moss, it has no oil on its surface, so wetting the particle is never an issue. The key in all this is to decompose the particle to the perfect point. The problem is still that the rate of salt release remains high at this perfect point.
Controlling the decomposition process, adding the correct nutrient buffer to adjust the ratio, feeding the plants the proper ratio of nutrients to offset the coco's "giving off" will produce the perfect growing conditions. When the medium is not taken into account, the results can be disastrous. Even when fed correctly, and the correct "buffer" of nutrient ratio set up, just one watering with plain water will wreck the buffer, sending the plant and medium into shock and rapidly escalating the potassium level. Consequently, plants that do not have enough of some ions like calcium (there are several) due to underfeeding or washing out will show a deficiency in these and other elements. Meanwhile, potassium builds up the plant tissue, ultimately leading to margin burning on the leaf surface, mostly at the tip. The first thing the inexperienced grower assumes is that he is overfeeding and has salt issues. He will decrease the feed concentration and leach the medium. This, of course, magnifies the problem and makes it worse. The key to proper coco growing is to use the right feed to balance the products the coco gives off. Think not only about availability, but about the ratio of one mineral to another as well. It is also important to water correctly.
Coco peat holds about 33% more moisture then similar grades of peat-based mediums if its structure is sound. Since a great amount of this is tucked away in the micro-pores, the medium can look dry but still be plenty wet. The same rules apply here as in soil or soilless mixes: water when the container loses 50% of the maximum water it will hold against gravity (immediately after drainage of a newly watered container). This is done by weight and yes, it does change with time, root mass, humidity, temperature and grower temperament (thumb on scale syndrome).
By controlling the decomposition and particle size closely, there is no need for anything to increase drainage, like perlite, and this removes a disposal concern. Even more air space can be achieved by increasing the fraction of coco fibers and husks. This results in a totally renewable and biodegradable medium that resists compaction. Finally, the pH of the medium, when buffered and controlled, remains constant pretty much throughout its useful life. The medium sets its pH at between 5.2 and 6.2, a perfect range, and will hold it there, unlike peat-based products that try to go back to a pH of 4.5 or less within three months of being planted. By using the correct age of coco with the right porosity, coco potting medium should be able to work through almost a year's worth of crops before being changed. The pH stays correct and only the structure changes, limiting the useful period.
So, we see that by controlling the aging process, using the correct ratio of nutrients, using the correct composition of nutrients, and pre-buffering the coco peat, growers can anticipate getting the perfect medium, correctly balanced, correctly composed, with good porosity, a water buffer, and a lot less headaches then peat-based soilless mix products. That is great for a start, but to complete a crop, it is critical that the correct nutrients be used as well. Consider coco as needing to be "fed" along with the plants. Once the medium establishes a buffer, which it will do based on the nutrients it sees, right or wrong, the grower can wipe this out by applying plain water to the medium. The medium hangs on to nothing and will readily flush away its nutrients; then the plant will suffer until the buffer is restored. Always use fertilizer when you water coco that a plant is actively growing in, at least at about EC = 0.6mS/cm3. This will hold the balance or ratio of the nutrients to each other and insure that the plant gets exactly what it needs.
