Q& A: Do I use hard, soft, or distilled water for Orchids?

When it comes to watering orchids, there’s so much misinformation out there, that it leads to bad habits and the eventual death of many orchids. The worst advice possible is the use of ice cubes, and I’ll mention that later below. But first, let’s start with the types of water and which is best for your orchids.
Best Water for Orchids
Image Credit: "Flowers" by bunnygoth is licensed under CC BY-ND 2.0 
With each city and country having different minerals and additives in the water supply, it’s best to get an overall idea of what types of water there are.

In this article, you’ll learn what each type of water is and what is best to use on your orchid.

What is the best water for orchids: hard water, soft water, reverse osmosis, distilled water, or rain water?

The truth is there isn’t one method that is preferred over another. Since each method will have pros and cons, our main concern is with the pH, chlorine, fluoride, and sodium levels to fit the orchid’s preference.

If pressured into a corner to pick a method above the others, distilled water is the best sources of water to choose for orchids, but also the less practical and most expensive. Rain water would come in second. In all the other methods, you’ll have to leach the potting medium (flush it out with excess water to remove salt build-up) or adjust the pH levels.

Are these the watering methods I use? No. And I’ll explain why at the end.

The Best Water for Orchids

What’s the best pH of the water for orchid growth?

It’s easy to throw all orchids into the same category and say they all love 5.5 to 6.5 pH… But this is true only of epiphytes, which grow on trees.

Lithophyte orchids will attach themselves to rocks and mountain boulders. The calcium carbonate deposits will raise the pH, and the orchids has adapted to thrive in a higher pH, of 7.0 to 7.9.

Terrestrial orchids, which grow in normal potting soil, will prefer a lower pH, and some can even reach lower pH’s of 4.5, like Phragmipediums.
For the sake of this article, I’ll just concentrate on epiphyte orchids. In this sense, our goal is to reach 5.5 to 6.5 acidity with our water, no matter what water supply we use: hardwater, soft water, distilled water, reverse osmosis water, or rain water.

If you don’t have one already, you can buy a simple pH test that is used for aquariums.

They usually run under 10 US dollars.
"orchids" by nickton is licensed under CC BY 2.0
In this graph below, the different pH’s of water are mapped out, whether they lean towards a more acidic or more alkaline ratio. It’s important to note that the potting medium will affect the pH, too.

That is why I threw in the sphagnum moss and the fir bark. Sine these are more acidic, they help in lowering the pH of your water.

If you grow your orchid in s full hydroponic or semi-hydroponic potting media, then you’ll only have the water to account for (this is why it's important to pick the right water).

Once the potting media decomposes, it can raise the acidity of the potting media, but not the way we’re aiming for. Decomposed material is an open invitation to bacteria and mold, and causes much suffering to the roots. 

A good sign that your potting media is decomposed and has been for some time is if fungus gnats start appearing around your orchids. If you want to read more about fungus gnats, this article is a great place to start.
Best Water for Orchids Graph
Image Credit: © Orchideria 2020

How Hard water Affects Orchid Potting Medium

Hard water is what comes out of the tap water when you open the faucet. Hard water will have an enormous quantity of ions and extra chemicals added to the water, like magnesium, sodium, chlorine, and calcium. Cities do this to make the water cleaner for the citizens to consume as drinking water.

Minerals inside the body are great, but for the rest of the house and our bodies, not so much. All the extra minerals in the water are what makes our hair dry, frizzy, and unmanageable. It turns our skin into dry, paper-like scales. (You get the idea…)

Hard water is also what leaves spots on dishes and other surfaces when we clean. Soap does not lather and make rich, fun-filled bubbles with hard water, and the worst—minerals in the hard water is what makes the buildup in the bathtub so hard to clean.

 Tip: You can check out your water hardness on the internet and the results should show up on a scale from 1 to 10… or 10+, as was my case here in Kansas. To know if your water is soft or hard, you need to test the GPG (grain per gallon) ration. You can access that information in your cities water supplier, and they will have a list of all the added minerals and how much is added per gallon.  The results will be like this:

    Soft Water- less than 1 gpg

    Slightly Hard- 1-3.5 gpg

    Moderately Hard- 3.5-7 gpg

    Very Hard- 7-10 gpg

    Extremely Hard- over 10 gpg

 How Does Hard Water Affect Orchid Growth?

 The minerals are excellent for our bodies, so imagine for orchids! They practically already have fertilization with every watering. But… that logic isn’t quite correct.

The tap water has a lot of minerals and ions added to it, but it also has chlorine, fluoride, and all the other minerals that harm the roots. Rain water, which is what nature uses, doesn’t have that many added elements to it, so the orchid has adapted to that. With all the extra ions in hard water, the orchid’s roots will decline to the extra minerals, making them less absorbent over time.

Another tip to consider: the pH of hard water is slightly alkaline (or Basic), ranging at 7.5 on the pH scale. Most orchids grow best in a more acidic pH of 5.5 to 6.5, which leans more toward the opposite side of the pH scale. If you use tap water, you need add a pH reducer to it.

Another good way to rid some of the components in tap water is to let the water sit out 24 hours before using it to water your orchids. Some of the ions will evaporate, making the excess chemical load not as bad as before.

This is what I personally use, just because if the method is too hard, time consuming, or complicated, I’ll end up not using it. So, tap water it is.

Soft Water for Orchid Growth

Orchid Smells
"文心蘭-小櫻桃 Oncidium Kutoo 'Little Cherry' [香港花展 Hong Kong Flower Show]" by 阿橋花譜 KHQ Flower Guide is licensed under CC BY-SA 2.0 
Soft water has been run through a filter to remove the additional chemicals. All the other substances that have been added to the hardwater to enhance our health (but screw up our pipes, kitchen sinks, and hair) aren’t present in soft water.

The filter is most likely a chemical one, using sodium chloride as a base to neutralize the chemical imbalance. Basically, soft water is water that has only sodium chloride added to it.
If you’re planning on drinking soft water, be advised that the sodium levels are high. If you have a heart problem or have a sodium restricted diet, then I wouldn’t recommend changing your water system to soft water. Again, the quantity of sodium that is necessary to remove all the other chemicals is extremely high.

Soft water is extremely harmful for the orchid because salt deposits can build up in the potting medium. (This also happens with hard water too, but the chemical build-up will be of other elements and not salt.)

You’ll notice a salt build-up when sunlight hits the top of the media and it sparkles, like the sand on a beach. If the build-up is really bad, you’ll see white spots all over the top of the potting media.

To get rid of this salt residue, you’ll need to leach your orchid. This is where you’ll run water (preferably that isn’t soft water) through your orchid for a longer period of time that normal watering is required to flush out the extra chemicals laying around.

Reverse Osmosis Watering for Orchid Health

Reverse osmosis (RO) is a water treatment which involves softening, dechlorination, and anti-scalent treatment, which ends up being extremely expensive for orchid care.

A residential unit of RO can be from the 200 to 600 US dollar range for a simple model, working all the way up into the thousand-dollar range.
orchid keiki
Image Credit: Photo by Jean-Louis Paulin on Unsplash
Reverse osmosis works because water is forced through a filter, leaving less quantity of ions behind in the original liquid. The impurities that RO osmosis can remove are far more than chemical ions: many bacteria are also removed that would normally appear in the tap water.

If you have a bigger collection of orchids or a larger greenhouse and have noticed more bacteria than most growers experience, RO might be a good solution due to their purification method.

Since my orchids are reduced to my home office, this option really doesn’t meet my demands.

As for the quality of this water: excellent. The impurities re removed and there are no excess chemicals introduced into the supply.

Distilled Water in Orchid Cultivation

Distilled water is a process where you can boil the impurities out of the water. Can you make distilled water at home? Yes. It would be easy if it was just about boiling water. But it’s not. It’s a bit more complicated, because you’ll have to boil water then capture the condensation that forms from it.

You’ll need two bowls, one inside the other. The smaller bowl sits in between the boiling water and the lid. The purest form of water occurs after it reaches the lid (during evaporation). When cooled, the water droplets condense, falling down into the second bowl.

The impurities will have left during this cycle, leaving your water distilled and clean.

This is the best method of watering that is found right next to reverse osmosis, but somewhat complicated to do at home.

Rain Water and It’s Properties for Orchid Propagation

Rain water is basically neutral when it falls from the sky. That’s what we learn in 5th grade. The truth is, it all depends where you live in the world, how pure o polluted your environment is, and what the rain hit on before it rolls down into the soil and into the water supply…but for this article, let’s say it’s mainly around 5.6 pH.
parts of the orchid
"[Central America] Guarianthe × laelioides 'Brechts' CCM/AOS (Lem.) Van den Berg, Phytotaxa 239: 67 (2015)" by sunoochi is licensed under CC BY 2.0
When it hits the grounds and soaks through the soil, it can pick up additives, like
and chalk,
turning it into slightly softer water with a lower pH.
Rain droplets can also bounce of leaves on the overhead canopy in the rainforest. On these surfaces, there are thousands of elements that have accumulated over time, and the water picks them up. When the orchid in its natural habitat gets rained on, the pH is neutral, but it still is high in minerals, ions, and other nutrients.

Remember, these two things are not the same: pH and hard/soft water. One is not necessarily linked to the other. Hard water doesn’t always mean a higher pH, just higher concentration of minerals and ions.

Don’t throw rain water into one category either… Depending on where you are in the world when rain falls, it can slide down calcium rock deposited, and the high calcium carbonate count in the mountain rock can raise the alkaline properties.

If you can collect rain water before it reaches the soil, this is the best source for watering your orchids. With the other choices above, you either have excess sodium or excess chlorine, or both. Not with the rain water. It’s inexpensive, too. Just time consuming, in my opinion.

Can I use Ice Cubes to Water Orchids?

This is a very common misconception, mainly because of one plant seller on the market. No, please don’t use ice cubes to water orchids. When you water with ice cubes, there are several potential problems. The first is the temperature. The initial shock in temperature will harm the fragile velamen, an outside cover for roots.

Most orchid grow in the tropical and subtropical rainforest, where the climate is hot and humid. They have never seen cold day in their life. In Brazil, it was literally 60ᵒ to 80ᵒ F year-round, and rain came down like hot tea. After a few minutes, it would cool off a little bit. The temperature of the rain water was a little cooler, but never cold—much less ice cold.

There is ONE study done that mentions the temperature of ice cubes in the medium. They argue that by the time the ice melts, the water that trickles down into the medium is room temperature.

Well, I beg to differ.

I’ve never had an ice cube melt and the water be at room temperature—ever. The aftermath of the melted ice cube was always cold. This difference in temperature is enough to shock the root system and harm your orchid.

Can watering with ice cubes be done? Yes. Will your orchid thrive? No.

The second problem with watering with ice cubes is that the potting medium is not watered as a whole, only where you placed the cubes. The information given on the info-card is that 3 ice cubes is enough to water an orchid.

Hold on a second… How big is your pot? What medium are you using? How old is your plant? All these are ignored when using the 3-ice cube method.

If you have a mini-Phal, three ice cubes don’t even fit on the pot and will drench your poor orchid. Even more because it is probably planted in purely sphagnum moss, which is highly absorbent.

If you’re cultivating an older Cymbidium in a 12-inch pot with excellent drainage, than the melted water from 3 tiny ice cubes won’t even start to hydrate the medium. Your orchid will die form lack of water.

Stay away from ice cubes. It works, and people have done it successfully, but it’s not the best for the root system or for watering purposes. Your water might be purer quality, (and there is a lot of emphasis on the word MIGHT) but it’s not worth it in the end.
So, in the end, what water is best for watering your orchid? Whatever water you are currently using. Cultivating orchids properly is not that much about the pH or which water you are using, but if you’re watering correctly.

If you over water or underwater, or if you soak the crown underwater, the results can be more dramatic than having a slightly more acidic or more alkaline water source. pH does come into play if you want fantastic large flowers, but to the everyday watering cycle, I personally wouldn’t worry about it. As long as you stay away from ice cubes, you’re good!

Happy Cultivating!
Signature Amanda Matthews
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