This is a fascinating new development in the orchid world - watering orchids with ice cubes! There is much discussion about the topic on all the orchid forums. For instance, an expert orchid grower for decades will say that she has never before heard of this method and can't think of a reason to do it when traditional watering methods work well enough. Then a orchid beginner will post that she recently purchased her first orchid from Walmart with instructions to water only with ice cubes, and it's stunningly beautiful 3 months later!
So what in the world is going on here? This article explains why this method works, and why I think whoever came up with it should be awarded for the Orchid Idea of the Decade!
The orchid that comes with this simple instruction is a popular and easy to grow variety known as the Phalaenopsis orchid or "phal" for short. It is also known as the moth orchid. Most orchids thrive with a particular kind of watering regimen that does not come naturally for an orchid beginner. Orchids should be drenched once a week or so, but in such a way that the water is allowed to pass completely over the roots and right out the bottom of the pot. Veteran orchid growers are accostomed to achieving this by making sure the orchid is potted in such a way that there is proper drainage and air circulation around the roots. We often bring our orchid pots to a sink and drench them. But it's a rare beginner who doesn't find this complicated. And this is completely different from the vast majority of houseplants that like a saucer full of water at the base of the pot. Do this to an orchid and it dies! Thus the trickle of water once a week from melting ice cubes may just be the perfect way to make orchid watering simple and fail-safe for a beginner.
There is a second aspect of the phal orchid that makes the ice cube method so interesting. Phal blooms are stunning and last a long time. When the blooming is over, this particular kind of orchid needs a cool period to trigger the growth of a new spike of blooms. This cool period includes a shift in temperature from approximately 80 to 55 degrees which is difficult to achieve in most homes. The cool water of the melted ice absorbed by the orchid roots is just enough cold to stimulate the growth of a new stem of flowers, or as we say in the orchid world, a "spike". Once again the ice cube is a brilliant solution.
How many ice cubes and when? I've heard of great results with anywhere from 3 to 6 ice cubes once per week. Place them on top of the orchid medium whether it is bark or sphagnum. I would avoid placing the ice right on top of an exposed root, but some claim that this is no problem. And as you can gather from this discussion, this method is only recommended for phal orchids.
