Filtered water for roses - advantages and disadvantages

I have a question, that has been occupying me for a long time, about using filtered water for roses in general, but preferably using it for rose seedlings. My basic water is alcaline and has a pH value round about 7,8 - 8,0 . So far, I used vinegar or citric acid for lowering the pH level under control of ph- measuring strips. Both mediums are evaluated differently.

The topic: @LarryD using vinegar to lower soil pH also highlights possible problems with both mediums, so I’m continously looking for a better solution. However, the alternatives are rare.

Water filters, typically carbon filters, are very controversial discussed and are considered as a breeding ground for many germs.

Therefore, does anybody have experiences with the use of filtered water for roses and rose seedlings and can allay my fears.

I woud be very happy for any opinions and advices !

Can’t ally your fears but have wonder for awhile switching to bulj distilled for aesthetic reasons (city water very hard). Probably would avoid the crud deposits.

Only for early days of seedlings. Have litres of unused B-1 Thrive l can add for weak feed into distilled. Might try this spring if any germinates.

1 Like

The problem I see with vinegar is lack of a definition and concentration precision. You need to know how much hardness there is in the water, then assume it is all present as carbonates, sulfates or some mix of the two. Adding acetic acid you will need 2 molecules of acid for each sulfate or carbonate. So unless you have a pH meter or a lot of pH paper it will be easier to stick with a growing medium that has a lot of peat or clay that can buffer the process by binding the solubilized salts of calcium and magnesium. Unless you water is very hard and used for a very long time it probably won’t be a problem during germination. I always germinate my seeds in vermiculite with calcium nitrate fairly high, then transfer the seedlings into some kind of potting mix plus garden soil to grow. Main factor controlling growth is light, then fertilizer. Hard water which we have here, has never been a problem.

1 Like

@RikuHelin @LarryD Many thanks for help and assistance !

I agree that light in correspondance with temperature is the main factor for controlled growth of seedlings. Recent years have shown that rugosa hybrid seedlings started well, but only a few weeks later, first chlorotically symptoms appeared which resulted in developmental disorders and were difficult to be repaired, neither with adding more peat and clay in this stage. That’s why my efforts go around to avoid such a situation from the outset. But I must see, that filtered water is probably not the solution. Bottled drinking water from the beverage market has mostly better pH values. Maybe this option can help at least indoors over the cliffs.

R. rugosa is definitely one of the pickiest when it comes to pH. I haven’t used filtered water for roses very much (assuming you mean filtration and similar systems that actually remove calcium from water, like reverse osmosis or water softeners). However, I do use pure/distilled water instead of tap water for all of my indoor plants, including rose seedlings. If you happen to have a home furnace or air conditioning system that produces water as a byproduct of its processes, or if you use a dehumidifier that condenses water from the air as it runs and catches it in a reservoir, those can be good sources.


@MidAtlas I understand. Thanks so much !

I use a tablespoon of citric acid to gallon. My water is slightly alkaline and it brings the PH down without burning.

1 Like

Hi Roseus. You do not say where you reside. If you live in an area with snow, you can use melted snow to water baby roses and house plants. That is what I do. I also harvest rain water in the Fall to carry me to the snow comes. Cheers

Hello prairielad! Thanks a lot for your attention to my question and your response. I am in the middle of Europe, so snow is more and more very sporadic in our region. Therefore, I have partially implemented the various inspirations. So far, the combination of distilled water enriched with very little fertilizer works quite well and no chlorosis is shown. I hope it stays that way.

I struggle with rugosas too… When I have plants at campus in the lab where I work, I typically water with reverse osmosis and it works very nicely, like Stefan described. At home my well water has an alkalinity of about 200ppm. There is pH and alkalinity. They are different, but related. Alkalinity is basically the bicarbonate equivalents. Too much over time builds up in the soil and leads to elevated soil pH over time. pH of the water is nice to manage since it impacts the solubility of water soluble nutrients we put into the water, but in my opinion it is more so the alkalinity that is typically the issue due to soil pH changes over time. We can have for instance water with higher pH and if there is also high alkalinity that is much more problematic than higher pH with low alkalinity. When I moved in I had my well water tested and that is why I know the alkalinity. I also bought an alkalinity meter too (like for fish tanks) to periodically check and it seems relatively consistent throughout the year. Sometimes if a person uses city water the pH may be elevated from sodium hydroxide on purpose. Lower pH water dissolves metals more readily. Cities want to protect their infrastructure and metal pipes from slowly dissolving. When I lived in St. Paul, MN the pH was kind of high (I think 7.5), but the alkalinity was low. It took a lot less acid to pull the pH down to 6.2 with low alkalinity than higher alkalinity.

With some formulas, etc. with my current well water I was able to calculate and later check that if I put 1.25ml of a concentrated sulfuric acid per 5 gallon bucket of water it brought down the alkalinity to an acceptable level (about 80ppm) and the pH too. I am very careful with the acid. There are other acids that are less challenging to work with, but you need more volume. I let the water sit for a day and can see some precipitate accumulate. I suspect it is calcium sulfate (aka gypsum). It is after that point I add water soluble fertilizer suspecting it’ll dissolve better and not precipitate out due to some pH issues and nutrient interactions. At the U of Minnesota for our black spot work, we try to grow some rugosas periodically in larger pots. We put in some powdered elemental sulfur into the mix so it reacts more readily when we repot the plants and that seems to help a lot to keep them healthy. With small pots and seedlings it may be hard to get concentrations just so and even in the little cells.

If you don’t have too many rugosas, the purified water sounds like an easy solution.

1 Like

Hello David! Thank you very much for your assistance and the clear illustration of the difficulty. I have now understood the problem even better. So far, I had obviously not focused enough on the alkalinity and concentrated mainly on the pH value. For the indoor culture I will get along well with the use of purified water. For outdoor culture, I will take your proposals into account. Of course, I have to check what can be best realized.