There is a distinctive smell in the air after it rains. It’s frequently linked with spring, as the smell of fresh-cut grass is associated with summer. You’ll find it in a lot of poetry and also on many inspirational lists of things to be happy about. What causes it?
The smells people associate with rain can be caused by a number of things. One of the more pleasant rain smells, the one we often notice in the woods, is caused by bacteria! Actinomycetes, a type of filamentous bacteria, grow in soil when conditions are damp and warm.
When soil dries out, the bacteria produce spores in the soil. The wetness and force of rainfall kick these tiny spores up into the air where the moisture after a rain acts as an aerosol. We breathe the spores in. These spores have a distinctive, earthy smell we often associate with rain.
The bacteria is common and can be found all over the world, which accounts for the universality of this sweet "after-the-rain" smell. Another smell is caused by the acidity of rain. Because of chemicals in the atmosphere, rain-water tends to be somewhat acidic, especially in urban environments. When it comes in contact with organic debris or chemicals on the ground, it can cause aromatic reactions. It breaks apart soil and releases minerals trapped inside, and it reacts with chemicals, such as gasoline, giving them a stronger smell.
These reactions produce more unpleasant smells than bacteria spores, which is why the after-the-rain smell isn’t always a good one. The smell of chemical reactions is most noticeable when it rains following a dry spell. This is because once the chemicals on the ground have been diluted by one downpour; they don’t have the same reaction with the rainwater. Another after-the-rain smell comes from volatile oils that plants and trees release. The rain reacts with the oil on the rocks and carries it as a gas through the air. Most people consider it a pleasant, fresh smell. It has even been bottled and sold for its aromatic qualities!
There are all sorts of other scents after it rains. So, when you talk about the after-the-rain smell with a friend, you may mean one thing while your friend is thinking of something else. You’ll both agree, however, that the air has a much stronger aroma to it after a good rain.
Q: How can I grow my blueberries in containers?
A: Blueberries make excellent container plants, but you’ll have to create a special potting mix. Blueberries need acidic soil conditions. Start with a 16- to 20-inch wide container. Create your own potting soil that contains 1 part peat moss, 1 part bark chips (for drainage), 1 part potting soil, and a handful of elemental sulfur. Choose lowbush or half-high varieties.
Although these varieties will produce less fruit than highbush varieties, they are shorter and will be easier to manage. Keep the soil well-watered and fertilized monthly with an acidifying fertilizer. In fall after first frost, move the container into a protected area for the winter. Blueberries need a cool period in winter, but extreme cold will kill the containerized plant.