Why Rainwater Grows Plants Faster

Rainwater is frequently collected by gardeners to use in conjunction with regular tap watering. Most people will say they do it to help lower their water bill and conserve water, but rainwater has many added benefits for plants.

Rainwater is What Plants are Used To

Because plants originally got all of their water from local weather patterns, plants are set up to receive rainwater. Rainwater is purer and more easily absorbed by the plant because it is naturally soft, or free of the minerals often found in tap water. This allows for healthier growth

Rainwater Helps Dilute Salts

Salt exists in the soil naturally. It is also added by the road salt used to melt ice in the winter in northern climates. Sodium (salt) is used to soften water in areas where the water is naturally full of minerals, such as calcium and magnesium, to reduce deposit buildup. Too much salt is bad for plants, as it starves the roots of water. Rainwater dilutes the salts in the soil and pushes them further down, away from the plant's root system.

Rainwater Has No Additives

Municipal water services add a lot of things to the water supply to keep it clean and sterile as it flows through pipes. Fluoride and chlorine are very common additives. Fluoride is put into the water in an effort to keep people's teeth healthy. Chlorine is used to kill off harmful bacteria in the water supply. Both of these chemicals affect the pH of the soil, often making it too acidic for plants. Rainwater contains neither of these additives, having been filtered by evaporation.

References

• University of Arizona Cooperative Extension; Harvesting Rainwater For Landscape Use; Patricia H. Waterfall; 2004
• University of Minnesota Extension; Rain Barrels, an Old Concept Made New; Rebecca Chesin; 2008
• Penn State Cooperative Education - Forest County: Extending Notes: Houseplant Care in Winter