Orchids in the Garden – Nutrition through Guttation
Article by Otto Moeller, Hannover, translated from the German magazine ‘Die Orchidee’
There is no life on earth without water.
Here, all life processes are dependent on water. Not only rain and snow are providing this water, dew and fog are also very important contributors. In the temperate zones, the amount of water arising from dew is estimated to be between 3 – 5% of the total precipitation. This dew can increase considerably in areas where the moist air rises from warmer river-beds up to cooler mountain slopes. In the dry areas of the world, the precipitation of dew can come to 3 mm per night. For the growth of orchids as well as all kinds of micro-organisms the additional supply of water in the form of dew is of much value; the presence of fog is equally useful. Now we will look at a different kind of precipitation.
The necessary flux of sap in plants is furthered by the evaporation of moisture over the leaf surfaces (low salt concentration). During periods of high humidity, this evaporation stops and the plants must continue to support the flow of sap by actively excreting fluids. There are particular areas on the tips of grasses, the toothed margins of fragaria (strawberry) leaves, alchemilla (Lady’s mantle) etc. called hydrasthodes (water slits) with specific cells called epithemes that serve exclusively to secrete liquids by guttation.
We have multiple records which show that inside the drip line of crataegus (hawthorn), the germination of Orchis mascula is extremely high, there can indeed be ‘beds’ of the young and flowering plants in these locations.
Test strips for diabetes were used to measure the sugar content in the guttation droplets of hawthorn and different grasses. The strips reacted noticeably and indicated a much higher sugar content for hawthorn as compared to different grasses. Besides sugars, plants also exude mineral salts and possibly other substances. Considering that different plants will contain different mineral substances, it may be assumed that this guttation supports a healthy development of the local micro organisms. A cycle of nutrition is thereby established, which aids in particular the plants with deep root systems. Where the surface layers of the soil are thus enriched with sugars, that is where the optimum germination of these particular orchids takes place.
One may deduce from all these things that to accomplish enhanced growth in our garden orchids, we must be more observant of the accompanying flora around our terrestrial orchids. We must also pay attention to the secretions in the root zone of these companion plants, keeping in mind that the plant parts above ground as well as the parts below ground will secrete substances that will be available for ‘recycling’.
Ingrid Schmidt-Ostrander - Canadian Orchid Congress