How important is the water I use on my orchids and how can I maximize tapwater?
 

Although I have had orchids for several years, I want to maximize their health and growth. I have recently been told that the water I use is of utmost importance- regarding Ph and chlorine content.

My name is Greg and I teach Algebra and Science in Miami Florida. I am new to the Board and I feel there is a lot I need to learn in order to maximize the health and well being of my babies. I have many questions, but watering seems to be a natural starting point. Thank you

Hi Greg, welcome to OB.

Some orchids are more forgiving than others regarding water quality. What kinds are you growing?

You should be able to find out a lot about your water from your local water utility. They should have a water quality report (testing is required by law), it may be available online. If you have access to the right equipment, you can measure some parameters yourself.

The most important question is, what is the total dissolved solids (TDS), expressed in ppm or mg/L? If the report does not give TDS, they should give electrical conductivity (EC), that can be expressed in different units. As a science teacher, I know you know how important the units can be. TDS, measured from EC, should be less than 200 ppm, lower is better.

pH is also important, water departments typically adjust to keep it near 7 or slightly higher. pH around 6 is usually good, pH can be reduced with a few drops of vinegar or lemon juice.

Alkalinity is also a good number to know.

Google the Saint Augustine Orchid Society, there are articles posted on their website that give more information on water quality.

Or you can put a few buckets out and collect rainwater!

While knowing your TDs is certainly the first step, a more detailed analysis of your water is a good idea. 200 ppm caused by groundwater contacting limestone is definitely not the same, from many plants' point of view as 200 ppm from saltwater infiltration.

Hope you can read the attached

Thanks everyone for the advice. I am going to start with my utility district.

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Thanks very much- Greg

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I have a bunch of Cattleyas and 10 Vandas

I take the clues of nature on this: Most of the tropical epiphytes we grow see rainwater that has picked up a tiny amount of air pollution, as well as nutrients exuded by the host trees. The TDS of that is usually somewhere in the range of 15-25 ppm - maybe a bit higher.

I mimic that through the use of RO, but tend to add more to it than nature does, ending up with about 25 ppm N and maybe 100 ppm TDS.

I follow Ray's advice. RO water and his low K fertiliser, in ultra low dose at every watering. I am getting serious root growth from that.