Types of Water

[HiOrcDen]

So I know that with certain plants, distilled water is specified. Is there a minimal 'condition' for water for all Orchids. For example, I recall reading that you should leave water out overnight for watering all orchids. Is this right?

Even if not required, are there benefits to using certain types of water such as distilled, spring water, etc.? Or could it be dangerous, if the plant is used to tap water?

One seller even told me they use well water, so how should I continue this treatment?

Thanks in advance!

[Dimples]

Leaving water out overnight to let chlorine evaporate is an outdated method. Most municipal suppliers use chloramine now and that doesn’t off gas. Leaving it out overnight to bring it to room temperature can be useful in cold conditions.

There is no standard quality for well water. Well water quality is regionally influenced. In some areas (like Southern California) the water will be high in dissolved minerals. Our well at work in San Marcos tested around 1,200ppm total dissolved solids, lots of calcium and magnesium but also a lot of sodium and chloride and other not so awesome inclusions. Well water in other areas can be very low in minerals, it’s all related to the local geographic and ecological conditions. I drank well water in NC that rivaled RO water.

Run of the mill orchids will be fine with tap water if that’s all you have. Sensitive species may need distilled or RO water. If you flush the medium regularly it will minimize mineral buildup from hard water.

[Ray]

Extending Dimples’ excellent response a bit - all orchids can benefit from the use of pure water. It’s what they get in nature, after all.

Pure water with a trace of complete fertilizer on a regular basis will yield healthier plants.

[Roberta]

What Dimples says is right on... First, most orchids aren't all that sensitive. At the Huntington Botanic Gardens, experience has shown that THEIR well water (high calcium) works better for their Paphs than pure water. (But then, most Paphs grow on limestone cliffs...) Other orchids not so much... everything else there gets RO water.

Before I got my RO system, I used a little vinegar in my fertilizer water to get the pH down to about 6.5 since the calcium carbonate in my tap water is a powerful buffer at around 7.8. With pure water, one needs a fertilizer that supplies some calcium and magnesium. Or mix in a bit of tap water with the pure water. I have a rather large collection, spread over my whole back yard. Only my small patio area and greenhouse get RO water. I put the more sensitive plants such as the Pleurothallids in the RO area. Everybody else gets city water (from sprinklers) and does just fine. I use RO and fertilizer designed for it (MSU Cal-Mag) to fertilize everything, but that's for simplicity. The plants that get city water would be fine getting fertilized with it, but I want to mix up just one batch, it works for everything.