Why you should not use softened water to root cuttings with your misting system

Can you use softened water to root cuttings?

Of course you can use water that has passed through a water softener to mist your cuttings with. It will provide the exact same amount of moisture that non-softened water will. However, that is pretty much all the benefit it will provide.

What is softened water?

Softened water is water that has gone through a process to remove calcium and magnesium. Water that has high levels of calcium and magnesium is called “hard” water. This hard water can cause scale and cause soap to not lather as well as it should. To remove the calcium and magnesium ions from the water, it must first pass over a bed of small plastic beads. These beads have a negative charge that holds positive sodium ions and as the water passes over them, the sodium ions swap places with the calcium and magnesium ions which have a stronger positive charge. Now that the calcium and magnesium ions have been removed, the water is then considered softened.

Once all the sodium ions have been replaced with calcium and magnesium ions, the systems needs to be regenerated. The regeneration process involves soaking the plastic beads in sodium. Sodium is salt. Yes, pretty much the same salt we eat and melt ice with in the winter. This salt is drawn into the chamber that holds the beads as a strong brine solution. This brine replaces the calcium and magnesium ions on the beads with sodium ions because of the sheer number of sodium ions. The brine, calcium, and magnesium is then flushed out of the chamber, the beads get rinsed with fresh water, and the entire process repeats itself over and over.

So have you figured out why you shouldn’t use softened water to mist your cuttings?

Even though the beads get flushed with water to remove the brine solution, there is still sodium present. As the water flows through the softener, the sodium ions are released into it. This salt can be lethal to your cuttings.
A small amount of sodium, as well as the calcium and magnesium that has been removed, is required for any plant to grow. Too much sodium, as well as the removal of the calcium and magnesium will have detrimental effects on the cuttings and may stunt their growth or kill them altogether.

I have personally witnessed the effects of softened water on rooted cuttings. During the softwood rooting season of 2008, I used water that was not softened and had tremendous results. Very high rooting rates were observed with nearly all species being rooted. During the winter of 2008, I had trouble with my hot water heater which led to a water test. This test revealed very large amounts of iron and manganese in my well water. As well as these high amounts, the water was extremely hard, this would explain why my water pipes had clogged up to the point of almost being completely closed. The solution for all these problems was a whole house filter and water softener. Of course, I never gave much of a thought to the cuttings I would be rooting the following summer!

Summer of 2009 rolls around to see me making thousands of cuttings and rooting them under my misting system. Almost at once I noticed the plants not responding well. Because of the extremely wet summer, I thought the cuttings may have been getting too wet. I made adjustments and forged on. Fast forward to late summer: the rooting percentage of that years cuttings as well as the general look and health was abysmal. Many had not developed nearly enough of a root system to survive. Many looked stunted and sickly. Some even had the edges on all their leaves brown and dead. Doing a bit of research, I discovered why; salt, and possibly nutrient deficiency due to the nutrients being removed from the water during the softening process. Yeah, yeah, I should have caught it earlier, but life sometimes just goes much too fast and I lost track of time and before I knew it, the summer was over!

So here is what I am going to do:

Come spring, I am going to add a valve just before my water softener. This valve will have a hose spigot attached so I can supply one of my misting systems with water that has not gone through the water softener. I will have one misting bed supplied with softened water and one supplied with water that has not been softened. During the course of the summer, I will pay close attention to the differences in the two misting beds. I am sure I will quickly see that the cuttings that are being misted with the un-softened water will be far healthier. when that is confirmed, I will then simply supply both beds with the un-softened water and note how  cuttings that were affected by the sodium turn out. Of course, things such as pH can also affect the cuttings, but because I don’t own a pH meter, I will not be testing that at this time.

Do you have any experience rooting cuttings with water that has gone through the water softening process?

What were your results?

For a great explanation on the effects of sodium on plants, visit salinitymanagement.org.

For info on plant propagation:

American Horticultural Society Plant Propagation: The Fully Illustrated Plant-by-Plant Manual of Practical Techniques

The Reference Manual of Woody Plant Propagation: From Seed to Tissue Culture, Second Edition

Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses

Hartmann and Kester’s Plant Propagation: Principles and Practices (7th Edition)

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