Horsemanure -   10 reasons to use it as orchid growing medium.
Why Horsemanure for Orchids

1. An effective and inexpensive medium.
   
2. A perfectly balanced food including a dozen or so trace elements.
   
3. A tremendous blossom booster.
   
4. As an extra bonus, the plants receive hormones, fungi and bacterium, which can affect the genes of the plant which stimulate better growth and an increase in the number and quality of flowers.
   
5. The plants produce flowers at an earlier age, sometimes before they are one year old and before they have produced their first bulb. This is a big benefit for hybridisers.
   
6. The plants become more resistant to pests and diseases. For millions of years up until about 100 years ago, plants received only natural food.
   
7. In my experience, the fresher the manure is the better. There are bonuses in this that are living things - hormones, fungi and bacterium. Allowing the manure to become old and dry may adversely affect these bonuses.
   
8. Plants in horse manure keep on growing in winter in Tasmania in an unheated glass house.
   
9. Because of the soluble elements in horse manure, you feed the plants automatically each time you water them. Computer control cannot improve on that.
   
10. Plants with very low E.C. (electrical conductivity) like Disa, will grow better in horse manure than anything else, but for these you do need a buffer to get the E.C. balance right. Sphagnum moss is a very good buffer. Fill the pot to 50 - 60% with horse manure then fill the top half with sphagnum moss. Plant the orchid in the sphagnum moss and water the plant every day freely with free drainage. This keeps the E.C. balance perfect and then you can't go wrong. For other plants, just plant them directly in the horsemanure. You can still put a little bit of sphagnum on top to help reduce weed growth.

There is no problem with salinity build-up when you feed the plant this way. Using Horsemanure is about feeding the plant, but of course there are other important factors to control for plant performance. They are temperature, humidity, light and E.C.

E.C. or electrical conductivity of a solution may be measured in micro Siemens (µS) and is an indication of the salinity of the solution. The higher the E.C., the higher the salinity.  The E.C. of the solution feeding a plant should not be higher than the E.C. of the plant because this causes 'reverse osmosis' where the the water and nutrients are leeched from the plant instead of the other way around.

Here are some tentative values for E.C. levels. 
800µS phalaenopsis, cymbidium, pleiones, cycnoches and catasetum.
600µS odontoglossum, oncidium, miltonias, lycaste.
400µS cattleya and paph group.
(The above figures were suggested by Wally Thomas and Barb Thomas as tentative values)
200µS disa

So you can see why disa should not be planted directly into horsemanure but rather planted in a buffer such as sphagnum moss with horsemanure underneath for the roots to take only what they need. Cattleya and paphs at 400µS may also do better if potted this way in a buffer.

For more about Using Horsemanure for Disas, click here.

Light and Temperature  click on this link light and temperature for information on this.