In North America, a trend in indoor gardening has been a shift towards sales growing practices versus hydroponics. One of the primary differences in this cultural practice is that plants are watered manually. This is usually accomplished with the aid of a submersible pump, length of hose, and a watering wand delivering the nutrient solution from a reservoir/cistern where the nutrients are prepared. While in hydroponics, the nutrients are mechanically circulated to individual planting sights typically via emitters, sprayers, flood/ drain fittings, etc. Also in hydroponics, there is typically much less growing media which is usually inert, and the nutrients are most often re-circulated.
Traditionally peat based soilless mixes have been the most widely used by growers. Bear in mind that you are much more likely to encounter a peat bog in North America than you are a coconut plantation. Since the supply is already in our backyard, it has been the natural choice.
Peat is typically stripped from bogs. The composition of different peat deposits varies widely, depending on the vegetation from which it originated, state of decomposition, mineral content and degree of acidity (Lucas et al. 1971; Patek 1965). The color may range from dark black to a light tan depending on the source, moisture content, and other parent material present. Basically, there are three types of peat: Moss Peat, Reed, Sedge, and Peat Humus. The one most commonly found in commercial
Coco coir is the fiber that results from the processing of coconuts (the removal of the “nut” from its fibrous encasing). The coir fiber is a by-product of an existing process and is quite renewable when compared to peat moss sources. The fiber is arguably more bio-
The coconut is teaming with naturally occurring growth hormones and other bio-stimulants that are inherent to the survival of the species, which fortunately for growers may be found in the fibers surrounding the “seed” which may be processed for use as a growing medium. As with peat, there are factors affecting the quality of use of the coir as a growing medium. The origin and age of the parent material largely play a role in the fiber qualities. Coconuts harvested when fully mature contain more lignins and cellulose. These fibers are tough and durable enough to manufacture rope from. Interestingly, coconut fiber is the only natural fiber resistant to breaking down in salt water. This helps make it ideal for indoor gardeners, as nutrient solutions, particularly popular inorganic varieties and the salts they contain, play a role in the erosion of growing media over the course of the crop.
After coconuts are harvested, the fibrous husk is removed from the coconut “seed”. An interesting fact about coconut harvesting from the Royal Botanical Gardens, KEW website: “… in some coconut-growing areas in Indonesia and Thailand the pig-tailed macaque monkey (Pithecus
After the coir fiber is separated from the nut, it is then soaked in slow moving pools or streams to moisten it, allowing for further separation and processing. If the coir fiber is intended for high value horticultural crops, care must be taken to remove salts. Often these streams are near or contain
To help determine the quality of your new and unfertilized coir fiber, flush 1.5 liters of distilled water through 1 liter of growing media, and measure the runoff with a dissolved solids tester. This is based on the Dutch RHP method of the analytical procedure. Chart 1-A illustrates the final analysis of two, coco coir samples that are well suited to growing applications based on their salt content. Note that the test does not provide information as to the structure of the
An overall value of 150 ppm or less characterizes a very pure material, while values up to 500
I have spoken with several growers who had tried coconut coir as a growing media several years back when it was first being introduced to the indoor gardening marketplace. They did not continue to use the media, and switched back to peat based soilless mixes. After working with some of the older coconut coir available I can see why. Firstly, the earlier coco coirs available contained extremely high levels of sodium. In one batch tested, the
Coconut coir that is optimal for plant growth also tends to be near neutral in pH (7.0). This helps ensure proper ionic balances in nutrient solutions, as fewer additions of pH adjusters are typically required to compensate for the pH of the growing media (i.e. Rockwell has a very high pH).
Coconut coir as a growing media can be purchased in either loose or dried and compressed forms. The loose forms are already hydrated and are usually ready to be added to containers or raised beds for planting. The compressed forms require hydrating. Although the hydration process may be laborious, the dried and compressed blocks are much easier to transport to and inside of the growing location. The blocks are ideal for remote outdoor gardens. In compressed form, the blocks typically take up about 1/5th of the space as commercial peat mixes, and are much lighter in weight. For example a 5KG block of compressed coco coir measures about 10” X 10” X 4” and when expanded yields near 72 liters of high quality growing media. That’s enough to fill nine 2 gallon pots; one block per 1000W HID lamp.
Some
Coir is the ideal growing media for organic and hydro-organic applications. The air volume retained harbors greater populations of beneficial (oxygen loving) soil organisms than peat mixes. Increased population levels of soil micro-organisms play a strong role in high yielding organic gardens.
One of the most impressive attributes of coconut coir as a growing medium is the level of aeration and structure supplied to the root zone. A coarse, good quality coir is difficult to over water. Basically, if you supply too much moisture it will just run out the bottom of the container, and will not become waterlogged (anaerobic) like a peat based mixes may. The coconut fibers are much tougher and coarser than those of peat. This means more airspace is available for drainage and to supply the roots and soil life with higher levels of atmospheric oxygen (O2). Coir fiber will not compact over the course of the crop as with peat. With peat, we all remember filling the pot right to the top at the start of the crop, 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 root zone, and increases salt buildup 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 physical coarser fibers. With 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.
Coconut coir is the ideal choice for raised bed production for several reasons. Firstly, many raised beds have been constructed without drainage. Moisture and nutrient management become much more temperamental in this type of growing situation. If you over water, there is much less of a chance of drowning roots. The coir fiber will retain air-space throughout the growing media, and the excess moisture will pool at the bottom, where it may wick up through the growing media, as coir tends to have excellent capillary movement of moisture and nutrients. To see just how resilient the air space is in coir, pick up a handful after thoroughly soaking and squeeze the material. When you open your hand, you may be surprised to find the media springing back like a sponge. Try this with peat, and you will not see any memory for macro pore space. Also, the coir fiber is resistant to breaking down under saline conditions, such as those found in non-draining raised beds, particularly those that are re-used over several crops. If the growing media is to be re-used the coir fiber will resist breaking down from mechanical handling (i.e removing old roots, mixing in growing amendments), while peat tends to become not much more than dust after several cropping cycles. In Holland, coir has been used to grow long term crops such as roses for periods longer than 10 years! The cation exchange capacity of the coir fiber also helps to reduce the incidence of salt burn, as it offers some buffering against positively charged ions such as sodium. When re-using any growing media, impurities such as sodium tend to accumulate over time. Organic based nutrients allow for a longer period of use over multiple crops, as they tend to have less salt as impurities.
Unlike peat, coir may be used in re-circulating applications. In re-circulating drip systems it is recommended that the fiber be mixed 50/50 with either coarse perlite, pumice or grow rocks for faster drainage. Coir is also very suitable for flood and drain applications. There are coir products now available in the hydroponic marketplace that are excellent substitutes growing mediums. One such product is a small, plastic wrapped square of compressed coco coir. Once hydrated it expands into a 6” X 6” X 6” growing cube. Moisture management may differ from other media. Another benefit is that coco tends to have a near neutral pH value, so lesser quantities of pH adjusters are required in the nutrient solution. Excessive additions of pH adjusters may create an ionic imbalance in the nutrient solution, locking out or precipitating some nutrients.
One of the greatest benefits to using
Courtesy of Maximum Yield Magazine