Water-softening salts can be toxic to plants

Q: I'd like to soften the water in our house, or at least get some of the minerals out of the pipes. Culligan-type water softeners are supposed to release a lot of salt into the ground, which I think is harmful for the plants. You can separate your softened water from your water for the plants, but I've heard that is not cheap. There are other so-called softeners that use calcium, potassium chloride or something else besides salt, but they are more expensive. What should I do?

A: I am not going to talk about the pros and cons of water softened with sodium chloride versus potassium chloride for personal use. This is not my area of expertise, but I can speak to the subject of watering plants with softened water and your irrigation system.

Normally, softened water starts after the water from the street has been tapped for your irrigation system. If this is done, it should not be a problem for you.

It most likely would be a problem if you tapped an irrigation system from a hose bib coming from the walls of your house. This means that softened water is delivered to hot and cold faucets as well as the hose bibs you use for hoses outside the house. So, if you have a water softener and you have some sort of irrigation system attached to a hose bib, then you are most likely watering outside plants with softened or saline water.

Whenever you use a hose attached to a faucet coming from the walls of your house, then it will be carrying softened water. If you are watering houseplants from an inside faucet and you have softened water, then you are most likely watering them with softened water.

Is softened water bad? Yes, it can be. If you are using inexpensive water-softening salts, then this is most likely sodium chloride or common table salt. Sodium is very toxic to plants and can destroy the structure of soils. Chlorides are essential to plants but in high amounts can be toxic.

What to do? As you mentioned, potassium chloride is an alternative water-softening salt to regular water-softening salt but it is more expensive. In fact, it can be double the price or more. Potassium is a mineral contained in fertilizers and used by plants in fairly high quantities. So potassium chloride would be a better alternative for plants than common water-softening salt.

When I installed my irrigation system, I put hose bibs in the landscape that were fed by the pressurized main line of the irrigation system. This way, when I watered with a hose I was not using softened water. I avoided using water from hose bibs coming from the house.

When I water houseplants, I use distilled or reverse osmosis water instead of water from the faucets. I mix a very small amount of houseplant fertilizer in the water so it has some good minerals in it. This avoided the use of softened water on houseplants.

Q: Could you tell what is the problem with my Eastern redbud tree and my mid pride peach tree?

A: The redbud problem is pretty common with this tree and our soils and climate. Western redbud is more tolerant of our conditions than the Eastern redbud and would be a preferred tree for the Western United States.

Western redbud may not be easy to find in the nurseries but is worth a look.

Another tree that might be an even a better selection for you would be the Mexican redbud, which looks very similar and would give you a similar impact to the Eastern redbud.

The problem you are seeing on the leaves, scorching and discoloration, will always be a problem in this climate and soils with that tree. Eastern redbud is an understory tree in the Eastern part of the United States, which means it does not handle full sun very well, even in the cooler parts of this country. Think of the problems it will have in our desert climate, high light intensity and alkaline soils.

This is a small tree that you would have to baby-sit for many years to come even if you've found the right spot for it. I would encourage you to look for the Mexican redbud if this is going into a desert or rock type landscape.

On to your peach tree. You have a great selection in a mid pride peach. Honestly, I don't see a whole lot wrong with it. The leaves are yellowish, but this is not due to iron. This is actually some sunburn and discoloration.

The difference between iron and bleaching by intense sunlight is in the coloration of the leaf. When a leaf is discolored due to high light intensities or sunburn, they tend to bronze in their yellowing. This bronzing is over the entire leaf.

Yellowing due to a lack of available iron in the beginning stages of the leaf's growth causes the yellowing to occur between the veins of the leaf, leaving the veins a darker green color. The term for this is in interveinal (between the veins) chlorosis (yellowing).

As the lack of iron intensifies, the yellowing between the veins becomes more pronounced. As the iron problem worsens, the leaf begins to scorch around the edges (it is unhealthy and cannot handle stress as well) and the interveinal chlorosis progressively gets worse.

At some time, and in some species, the entire leaf may become totally yellow with scorching on the leaf margins and the veins only with a hint of green in them.

The best type of iron chelate for us is also the most expensive one. But a little bit can go a long way. The only place I have seen this for sale in retail packages in small homeowner quantities (one pound) has been at Plant World Nursery in Las Vegas.

Don't forget I will teach a fruit tree pruning class at the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas starting at 9 a.m. Saturday. I have the agenda posted on my blog at Xtremehorticulture of the Desert. For directions to the orchard before Saturday, call 702-257-5555. It is 100 yards east of the intersection of North Decatur Boulevard and Horse Drive in North Las Vegas.

Bob Morris is a horticulture expert living in Las Vegas; he is on special assignment in the Balkh Province, Afghanistan, for the University of California, Davis. Visit his blog at xtremehorticulture.blogspot.com.