We have all heard the saying ‘April showers will bring May flowers’; however, I believe that there is more to May’s abundance of flowering plant life than rain. The warming temperatures and wakening of the soil surely have a profound effect on the emerging foliage of spring.
There is more to rain though than one might think and I presume that the person who coined the phrase did so to cleverly imprint the importance of spring rain onto the brain of many gardening enthusiasts.
Have you ever noticed that your outdoor plants and flowers may appear larger, greener and more lush after a good soaking rain? If you have, you were not imagining the subtle differences that you observed. The change in your plant’s appearance was most likely indeed due to the rain.
Rainwater is considered to be 100% soft water as it falls. It is slightly acid naturally and should not be confused with ‘Acid Rain’ which is much stronger and caused by different gases. Rainwater is free of salts, minerals, chemicals and pharmaceuticals all of which may be found in some city/ ground water in varying amounts. If you have ever noticed or observed a whiteish/gray ring around a clay pot, that is from an abundance of salts/chemicals building up and leaching through the clay from tap water that has been used to water the plant.
Most organic green plants like a soil Ph level of 5.5-6.5 (this is on the acid side of neutral Ph 7) and is the natural Ph range of rainwater.
Rainwater contains nitrates an important macro-nutrient. The nitrates in rainwater are the most bioavailable form of nitrogen which is needed by plants to thrive and grow lush foliage. Many forms of nitrogen are not able to be absorbed by plants. The nitrates made up of nitrogen and oxygen in rainwater are formulated naturally for maximum uptake by plants. Nature designed most plants to absorb their nitrates from the soil, provided by the rain.
It is interesting to note that the amount of nitrogen in rainwater usually increases during a thunderstorm caused by the lightening. The high temperatures of the lightening can provide enough energy to combine the nitrogen and oxygen in the air forming nitrogen oxides which dissolve in the rainwater and form nitrates.
Also of note is that ground/well water does not lack nitrogen but the soil and rock deep in the earth tend to add various organic salts to the water as it percolates through the soil particles.
Rainwater is indeed something special to the plant world.
Dawn Conrad is a Virginia Cooperative Extension Master Gardener, Herbal enthusiast, Writer and Fiber Artist. She can be contacted at dawn@ mygardenmuse.com.