Every year readers ask what I think winter is going to bring us in terms of snowfall. Sometimes this question comes from gardeners who realize that snow contains nitrogen and is considered the poor farmer’s fertilizer. Other times it comes from skiers who think I might have some sort of garden line to the weather and whether they should get a season pass.
Loads of snow? I have been writing this column for 45 years — this month — and I still cannot figure out why I am supposed to be a weather prophet. Perhaps you are all so used to seeing references to The Farmers' Almanac weather predictions.
Actually, there really is a direct connection between plants and precipitation. What makes it even more interesting to me is that it also involves my favorite subject, microbes. I still can’t know the answer to what is going to happen this winter, but at least I can pass on a better understanding of what it takes to make it snow.
I have written about Pseudomonas syringae before. This is a common soil bacterium which appears to have about 50 different strains that are plant pathogens. It is named after the common lilac on which it is often found. Another plant it affects is the tomato.
For this column, forget the disease problems caused by an infestation of Pseudomonas syringae. Instead, know that this bacterium also produces a protein that causes dust and water to be attracted to it and causes water to freeze at higher temperatures than normal. Droplets formed around Pseudomonas syringae high in the atmosphere turn into ice crystals.
What follows next is is all pretty simple, but also simply amazing. As you know, plants draw water from the soil and eventually release it into the atmosphere This water vapor contains Pseudomonas syringae microbes, which float upwards to form and then join existing clouds. These bacteria “seed” the formation of ice crystals. When the ice crystals become heavy enough, they fall back to Earth. Rain or snow.
It may be easier to think of an Amazonian rainforest or your experiences while on Hawaii vacations. Every day, late in the afternoon, it rains. Why? It is because the trees in the area transpire water and Pseudomonas syringae starting in the morning and continuing all day. Eventually, this moisture causes clouds to form and eventually rain, too. This is called bio-precipitation and while algae, fungi and even diatoms can be involved in seeding clouds, it appears Pseudomonas syringae are the dominate nuclei found in rain and snow.
As an aside, I like to put a small pearl into the occasional column that my friend Frank can use. Well, take note. If you ski at Alyeska like he does, you need to know all this stuff about Pseudomonas syringae. I am betting that Alyeska, like so many other ski areas around the world, buys a commercial brand of Pseudomonas syringae, which is used when making snow.
Now, I am trying to wrap my head around this information. Our snow, even the man-made stuff at Alyeska, involves Pseudomonas syringae, which may have come from your lilacs. That ought to be enough of a connection to connect gardening to the weather, even if the Pseudomonas syringae that seed our clouds during the winter months probably comes from someplace else.
So, will we have more or less snow this winter? Will it rain a lot? I can’t tell you, but I know a certain garden bacterium that can.
Jeff’s Alaska garden calendar
Alaska Botanical Garden: Learn about virtual classes and field trips this winter. Get the newsletter. Join. alaskabg.org. There is plenty out there. Take advantage of it.
Bird feeders: If you generally don’t have bears this time of year in your area, fill one feeder and see what happens. No sense rewarding too much any that happen by.
Houseplants: Water them! Start paying more attention as the heat is on for the duration, and they can easily dry out.