You can water RdV with distilled or rain water and I have found that adding Miracid to the irrigation water counteracts alkalinity. Sometimes I save the water that the air conditioner pulls out of the air by allowing it to drip into used gallon plastic milk jugs. This is essentially distilled water. Also some people put vinegar in the water that they give the plants. I do not remember exactly how much but you can find out in Strawberryhill's old posts.

Cath

10-20ml of vinegar in 10lt of water every so often should help (sorry about the metric measurements, just calculate 10-20 parts in ten thousand). If you intend to keep it potted, potting it in more acidic substrata (e.g. potting soil for camelias) will fix the problem for some time. That is, if it is really a pH issue and not a lack of nutrients in the pot substrata. Fertilizer used should contain Fe micronutrient in chelated form and be lean on the P side.
Nik

This post was edited by nikthegreek on Sun, Jan 26, 14 at 23:37

When you choose fertilizers for chlorosis-prone roses, look for those made for acid-loving flowering or fruiting plants (azaleas, rhododendrons, gardenias, blueberries, etc.). You can also mix unbrewed coffee grounds into the potting mix, or layer some on top of the soil where it's planted for mild acidification. Peat moss will help, but I'm assuming there's already some in the potting mix. I remember that cottonseed meal is an acidic organic fertilizer, and it's probably already used in mixes for acid-loving plants. You could also get the stuff used to turn hydrangeas blue, but use it very sparingly in pots -- very weak strength, stop when chlorosis goes away, and don't resume until it starts to show again. If it was me, I'd start with an organic fertilizer mix in the soil, maybe some unused coffee grounds, and modify with the water-soluble stuff as-needed.

:-)

~Christopher

Sorry to have to chime in again, but just a warning not to use aluminum sulfate (the stuff that helps hydrangeas turn blue). It can acidify your soil to some extent but adding any acidifying agent will do the same , it will not turn your rose blue and it has every potential to be phytotoxic. Just use a slightly acidic potting soil. Aluminum sulfate does not turn hydrangeas blue because it acidifies the soil, it turns them blue in an acidic environment because Al is absorbed easily by the plant which plays some nice games with the particular plant's natural pigments. Excessive Al can easily be phytotoxic to many plants and a pot enviroment is not very forgiving of such mistakes.
Nik

This post was edited by nikthegreek on Mon, Jan 27, 14 at 1:25

Ah, thanks for clarifying. I was just trying to think of acidifiers off the top of my head.

:-)

~Christopher

No problem. It is easy to provide required pH conditions to a potted plant. Just use the correct substrata. Even adding some untreated (unlimed) blonde peat to common potting soil will do the trick.

As I said in my first post, this all is assuming there IS an issue with the pH being unsuitable for the plant in the first place.
Nik

An old lady who lived next door always stuck a piece of iron (example, a piece of rebar) in her pots of certain plants; I guess the idea was that iron would leach into the soil. I've started trying this, too; for example, I have my RdV trained on a tripod made of rebar. I can't say that I remember it suffering much from chlorosis at all. I also do try to throw in organic acidifiers (thanks for tip about the coffe grounds,Christopher!) bart

Sticking pieces of iron in the soil or in pots in the hope that this will counteract plant iron deficiency is under most circumstances just a voodoo like practice. Fe is seldom lacking from soils, the issue is that it can be unavailable to the plant due to chemical reasons. Soil Fe chemistry is very complex. As far as I know without being an expert on the subject and generally speaking, best corrective intervention is by foliar applications of iron sulfate while best long term remedy, if iron deficiency is due to inappropriate pH (the commonest case), is fixing the soil pH and limiting P applications to those strictly necessary for plant nutrition. Soil applications of chelated iron help but care must be taken for the chelated form to be appropriate for the soil pH. Chelated iron is also prone to rapid photolysis, thus it should be applied at dusk (and covered if applied in its solid form rather than as a drench).
Nik

These helpful posts have jogged my memory. Another thing I do is mix green sand in the potting soil. It is slightly acidic and higher in phosphorous. Both of these attributes help to balance out our alkaline water which is very high in calcium.

Cath

Some of the Blueberry growers on the fruit forum are always facing this situation. They are using battery acid to make their alkaline water suitable. It costs less than the vinegar and something about the vinegar being used so often had bad results on the soil and plants. They were making large trash cans full of acidic water to use on the blueberries. This worked for my Azaleas. Even if you fix the soil, eventually the water turns it all alkaline again and the plants get chlorosis. Adding iron won't help because the plants can't use it until the soil is fixed. Strawberry is very good at getting the soil right if you want to ask her on the Organic Rose Forum. The blueberry folks say that your test strip should read the same as a strong cup of black coffee when you test your adjusted water.

Thanks for all the help everyone! I think for now I'm going to have to use vinegar to help balance the water pH and being the soil back down to acidic conditions. I might look into the battery acid, but despite me being a Biochemistry student my mother balks at the notion of having "chemicals" in the house (you should've heard the fit she threw when I started making lye soap using 100% sodium hydroxide that was labeled as a drain cleaner).

You guys are great!

Josh

Josh, you can buy lye soap if your mom is freaking out about making it yourself. For spraying on plants, look up Kirk's Castile Soap. You can dissolve it in boiling water, let it cool, and further dilute it for a sprayer. I don't remember the exact recipe offhand, but I'm sure you can find it by doing a google search.

:-)

~Christopher

Battery acid sounds dangerous and poisonous! What is it exactly? bart

'What is it exactly?'

Diluted (about 30%) sulfuric acid mostly, afaik.

Nitric and phosphoric acids (sulfuric less so) are routinely used in commercial scale agriculture to acidify irrigation water. They provide nutrients also (nitrogen and phosphorus respectively).

Ready made nitric and phosphoric acid weak solutions are available for small scale - amateur use variously branded ('pH Down' is one such product). Apart from these, for the amateur user, citric acid (the stuff that makes vinegar acidic) solution may be a better choice (with regards both to handling hazard and plant health). It is more expensive than the other acids though so it is rarely used commercially.

PS and Disclaimer: Concentrated acids can be a handling hazard. Not recommended for home use unless you know what you're doing and have proper handling equipment. Nitric acid is especially tricky to handle due to its viscous nature.

Acidic solutions corrode metals so never pass acidified irrigation water through metal pipes, pumps etc. Acid proof 'plastic' irrigation equipment should be used. Passing acidic solutions through metal irrigation equipment will not only shorten the equipment's life but may pollute your soil with heavy metals also.
Nik

This post was edited by nikthegreek on Tue, Jan 28, 14 at 6:16

Nik -- vinegar contains acetic acid. Lemon juice contains citric. Both will lower pH immediately, but both will wear off quickly, as they biodegrade in the soil.

Yes indeed, I stand corrected regarding citric acid. Thank you.
Acidification of irrigation water on a commercial scale is not used mainly for correcting soil pH although it helps, it is used for correcting water pH (and thus the pH of the soil solution during and immediately after irrigation) which has effects on fertlilizer solubility and availability, alleviates some effects of soil sodicity, affects salt leaching, avoids irrigation emitter clogging etc. In short, it is done to avoid accumulation of problems rather than rectify issues. Btw, pH is only one of several factors which affect the quality of irrigation water. High water pH is usually an indicator of excessive dissolved bases (usually lime) and it is these that cause most issues.

Having said these, in a pot environment where irrigation is frequent and substrata buffering capacity is relatively low, acidifying the water helps with keeping pH lower (and reversely, watering with unsuitable water has the most negative effect). But, as I said before, selecting a more appropriate substrata should be the basis to start with.
Nik

This post was edited by nikthegreek on Wed, Jan 29, 14 at 1:09

Yuck;I definitely think I'll stick to vinegar,lemon juice, and rebar stuck in the soil.Battery acid! and then you're supposed to eat the blueberries???

Sulfuric acid is good for you once digested by the soil and plant... It contains the very yummy elements Sulfur, Hydrogen and Oxygen. In contrast I find manure utterly disgusting, what with all that insipid Carbon and distasteful Nitrogen it contains.
Nik

This post was edited by nikthegreek on Thu, Jan 30, 14 at 4:20