Soft water for plants?

[longdogs]

Hi all

Does anyone know if plants are affected by the salt in a water softener. A customer of mine had the softener fitted about six months ago and has noticed that her plants are showing signs of distress but she is not sure if it's just due to the hot weather or the salted water coming from the garden tap. Despite the fact that I am a plumber, I have to admit that I don't know the answer.

Thank you

 

[dizzydee86]

Excellent question with mixed expert opinions. The salt in the softener does cause long term changes in the soil chemistry. The soil acts as a buffer for the ions in the water however over time the soil can lose it's 'buffer' ability. It is a similar to the long term effects of acid rain, which actually damages roots rather than burning leaves as most people think. If she is to continue using salted tap water then I would suggest leaving the water to stand overnight to allow any excess salts to decompose before watering. However I would prefer to avoid this altogether and if space permits fit water butts somewhere on the property to utilise rainwater. Also if she is able to I would use a good soil fertiliser to recondition the soil of her current plants or replace the top few centimetres of soil with a quality make.

 

[HERTS P&D]

Softened water does damage plants. The cold kitchen tap and any external garden tap/s should be off the mains. Kitchen for drinking and garden tap/s for the garden. Just think how much salt/money is being 'wasted' on the garden.

Andy

 

[longdogs]

Thank you for your answers. I have passed them on to her and advised her turn off the softener if she has to use the hosepipe and also to invest in a water butt as suggested.

 

[JohnD]

softened water does not contain salt. That isn't how they work. It does however contain a tiny amount of Sodium Bicarbonate (the stuff you find in indigestion remedies).

As for letting it stand, this will have no effect on the quantity of bicarb in the water, nor would it have any effect on the amount of salt (if there was any, which there isn't)

I use softened water on my housplants and they are fine. However it is wasteful to spend money on softening water which you are then going to hose about the garden, so it is normal to have an unsoftened tap for garden use.

Soft water is very good for washing the car though.

 

[dizzydee86]

Sorry JohnD but you slightly misunderstand the terminology used. Salt is a very broad term for many different compounds and chemicals. Saleratus meaning 'aerated salt' is the old name for both sodium bicarbonate and potassium bicarbonate. So softened water does contain salt though not the sort you put on your chips! Sodium ions from the salt (sorry sodium bicarbonate) replace magnesium and calcium ions in the water (the ions that make water 'hard'). As the sodium bicarbonate in the softener is depleted, sodium chloride (table salt) solution can be added to replenish the sodium in the softener.
As for leaving overnight - this allows longer for the free sodium ions in the softened water to deplete as it reacts with the other ions in the water. As for softened water being fine - most experts agree that this is not the case - sodium although beneficial to some plants in very small doses is in fact toxic to plants in higher doses. Also plants need a certain amount of calcium and magnesium for growth which are removed by the water softener. Early signs are stunted plant growth due to root damge and brown tips on the leaves. Watering with softened water causes a gradual build up of sodium in the soil and as I stated earlier whilst the soil can act as a buffer to these ions, over time this ability is depleted unless soil is replaced. Think I may still have a book on environmental & soil chemistry that may explain these effects better than I can.

 

[JohnD]

Sorry JohnD but you slightly misunderstand the terminology used....

Thanks, but I am aware of how ion exchange works, and I also know what the term "salt" conveys in normal speech by English speakers.

 

[dizzydee86]

Oh apologies to you JohnD. I'm sure the OP knew what we meant by salt as he used the term himself. I was only trying to give some advice that could save someones treasured plants, having suffered a plant annihilation myself when I was away for three weeks and mine were watered to death! Out of interest how long have you been watering with softened water?

 

[JohnD]

20 years.

 

[dizzydee86]

Only asking as I was having houseplant problems and after some research found it was down to long term use of houseplant fertilizer. Even with intermittent use, apparently there was a build up of chemicals in the soil and was advised that every 2 months I should run the whole pot under running water to flush out the soil. Most people are afraid to do this as they are afraid of overwatering however there is no risk so long as you give them ample time to fully drain. According to the former nursery owner I heard this from this is the next most common cause of house plant distress after under/over watering and is a bigger problem even than pest infection.