For years, I have been starting plants indoors for my annual vegetable garden and have had more than my share of success.  I have also propagated innumerable herbs, shrubs and trees—both from seed and from cuttings. Nevertheless, I have had very mixed results in my recent attempts to root hardwood cuttings INDOORS.

Last year, for example, I went to great lengths to prepare several hundred Sea Buckthorn cuttings during the winter. I tried some in sand and some in water, where I could more easily observe what was happening. While many of these BEGAN to root, ultimately both batches failed. What had gone wrong? Perhaps they had suffered from a bacterial or fungal infection? Perhaps the sand I used as a rooting medium wasn’t sufficiently aerated?...But 100% failure? There had to be something I was missing.

This year, I acquired some Devil’s Ivy (Epipremnum Aureum) cuttings which were already rooted and in water when I got them.  Since I wasn’t ready to pot them, I left them in a glass of water in my kitchen.  Over the next several weeks, I watched in confusion as the healthy white roots turned black and began to rot before my eyes.

Simultaneously, I was attempting to root some pussy willows in water so they’d have a little ‘jump’ on the spring.  I knew from experience that willows rooted readily in water, so I expected a high level of success…And so I was surprised when the same phenomenon occurred that I had previously seen with the Sea Buckthorn: little white root ‘nubs’ would form, and then almost as quickly, they would die back to the stem.

The failure of the Devil’s Ivy and Pussy Willow provided the information I needed to isolate the problem, since I knew from experience that BOTH of those species had EVERY REASON to root successfully:  It had to be my water!

Here in Kelwood, our tap water comes from a town well.  It is well known to be extremely HARD—for example, if I heat a pot of water on an element, there is mineral scale visible on the pot even before it reaches a boil. A quick ph test revealed that my tap water had a pH of 7.6—also quite alkaline.  After a little “Google-Fu”, I found the following excerpt in a book titled “Plant Propagation”—by M.K. Sadhu. In this section, Sadhu is talking about MISTING cuttings:

“The optimum pH of the water for misting is 5.5 to 6.5.  Hard water or alkaline water is not suitable for mist, because a build-up of alkalinity in the rooting medium due to continuous use of hard water may inhibit root growth or prevent regeneration, especially on slow or difficult-to-root plants. In hard-water areas, it is better to use rain water or install water-treatment equipment which remove dissolved salts from the water.”

Was it really this simple?  Was my water unsuitable for rooting plants because it was too hard, too alkaline, or both?  It seemed easy enough to test:  I took the languishing Devil’s Ivy and Pussy willow cuttings out of the tap water they had been sitting in and replaced it with water collected from snow-melt, which had a pH of 6.5.  Within 2 days, evidence of additional root growth was observed on both the willow and the ivy.

I will continue to monitor root development in this experiment, but have already concluded that whether or not the water WAS, ultimately, the culprit in my failed rooting attempts, I will be switching over to rainwater for ALL of my irrigating in the future!

I hope this information is helpful to some of you!

-Tim