Orchid Culture: Media

Orchids grow in a wide range of media. Almost anything imaginable can be used. Orchids benefit from the moisture and nutrient reservoir that many media mixes provide. In addition, orchids depend on the media to physically support itself.

Choosing the type of media you want to work with is subjective based on what is available, economical, and adaptive to your growing conditions. There are probably pluses and minuses for each choice.

The media and formulation you choose is extremely important to maximize your orchid's vigor. It will affect your watering, fertilizing and in some cases what you can spray on your plants. Some medias require a pH adjustment. Some are organic and break down while others are relatively inert like aggregate or volcanic cinders.

We favor coir while other growers find it less than desirable. If you are interested in adapting your growing to include coir, more tips are provided. Media is a personal choice. There are a great number of different media mixes so you just need to assess what will work for you in your location.

Coir

After experimenting with a number of different media mixes over the years we are thrilled with coir. But it did not come about without some hard knocks. All coconuts are not alike, especially when it comes to processed coco chips and finely ground coir. Salt content needs to be relatively low and the salt content in coir will vary from company to company. Some companies guarantee an EC level that is probably worth the extra price you might have to pay to ensure quality.

The age of the coconut husk is also very important. Chips made from green (un-aged) husk were sappy, and as a result the orchids did not do as well in this media.

One thing worth noting is the wide range of chip sizes: Some bags labeled as "Small" were equivalent to a "Medium" from another manufacturer. Sometimes the sizing differed from bag to bag with the same supplier. They are chopped by hand and the grading is not always consistent. You may have to resort to a Crystal ball to find the best supplier in your area.

What sizes are good and what is a good mix? We believe this is relative. We use several different mixes to accommodate the conditions at each of our two locations. You can experiment with various ratios of chips to coir for your transplants. For our Waianae operation -- a relatively arid location -- a mix of about six parts chips (1/4" to 1/2" in size) to one part coir works well for most genera in our inventory. If your location is not as arid perhaps you will need to reduce the coir.

One positive aspect ofcoconut is it tends to be weed seed free. This has saved us from many hours of weeding.

What are some of the drawbacks? Coir retains water and may be too wet for areas with constant rain. It is also relatively free of microbes. Thus symbiotic microbes are not present in any level to even begin a population that is beneficial to orchids. Beneficial microbes not only aid in breaking down nutrients into useable form for the plants but they also can keep any potentially pathogenic ones from growing and eventually becoming a problem.

We have not explored enough of the wide range of available inoculants to really recommend any particular product because they all seem to provide some benefit.

We believe that a large diversity in the microbial community can ultimately provide the orchid with biostimulants and disease suppression. So instead of drenching with a fungicide when we transplant, inoculants are added to the media to provide populations of microbes to aid in disease suppression.

Composted materials are rich in beneficial microbes and we are presently experimenting with the art of media making. It's almost like baking bread. When bread is inoculated with yeast it results in the rapid multiplication of microbes and the production of gases that causes the dough to rise. So is our media rising? It doesn't smell like bread but it does have a somewhat pleasant aroma, like the good earth.