[David Dickinson]

I have been reading a lot recently about this technique. Some people swear by it and others say "Try it, what harm can it do". Living in Rome where the water is very hard, if it really can do no harm, I would like to try it - thus increasing the number of species I can grow. Does anybody add vinegar to the water they use for pot plants? Does it really produce healthier plants? I am thinking of trying to grow some Leucadendrons. Does anybody use vinegar in their water?

[david glen]

Would it not be cheaper to use bottled water ? Of course it will depend on the %'s required .

[ritamax]

One can use vinegar or citric acid to correct the pH.

[David Bracey]

How will you calculate the amount of vinegar/citric acid to arrive at what pH?

[ritamax]

The amount is dependent on your water pH and the pH you want to reach. I would definitely start with a weak solution and test the pH first with test strips sold in a pharmacy or a test kit for aquariums. Vinegar alone will kill the plants. It is used as a weed killer as well. There are also some products to lower the pH in water for aquariums. The effect is very shortliving in the soil. I know people who get away with it as they have just some pots they need to keep on the acid side and they water them regularly in this way. For a long run a good thing would be to use some filter for your tap water to purify it (good for your health and your electric devices as washing machine as well). Adding sulfur in the soil will lower the pH in the soil, if the soil is already alkaline (the soil gets alkaline in time, if watered regularly with alkaline water). Or using some potting compost for ericaceous plants or adding some acid mulch such as pine bark. This matter is highly complex and there is probably no way to control it completely, otherwise one would have to test the soil around every plant regularly. 

[ritamax]

Some words more about softening the water. A common method of ion-exchange, where the calcium and magnesium is exchanged with sodium ions (the same principle where salt is added in the dishwasher) is not good for the plants. Boiling the water will soften it, but the method is practical only if very small amounts are needed. There are some water softening products for plants available, they are easier to use than vinegar in water, which has to be tested for pH, but more expensive. I use water passed through a Brita filter (has a softening effect) for my indoor potted plants. We use that water for coffee and tea as well in Basel, where the water is middle hard. In Spain the tap water has chlorine, heavy metals, salt, nitrates etc. in it, so a filter for the entire house is essential, otherwise all that stuff will get in the soil with the irrigation. There is not enough rain water to collect which would be obviously the best for the plants.   

[Hilary]

I followed all the discusion about adding vinegar to water plants which are suffering from lack of acid.
I have this potted  hibiscus  which has  never looked very healthy.
Recently I have given it a few drops of vinegar now and then.
As you can see from the photo the leaves are beginning to look greener.
Hilary

[greengrass]

Yes the pH is crucial to plant health. For example Rhododendrons and Camelias will not grow in alkaline soil.
Rainwater is always the best! - Why? Thats because during its process through the atmosphere it absorbs CO2. When it arrives at ground level its pH is generally between 6.5 and 7.0.
The reason pH is crucial to plant well being is because the higher the pH above 7.0 (neutral) the more the roots are blocked from absorbing nutrients, so adding something like vinegar to an alkaline soil always improves the situation. In some instances you can pour gallons of fertilser onto plants, but because the pH of the soil is too high then they just can't absorb the nutrients.
But remember alway know where you are before attempting the journey, cause plants will also die if the pH is too low.