Thursday, July 28, 2016

Plant Transpiration

Humans have a process through which they release water in their blood vessels to the air around them - called perspiration.  Plants have a similar system, where water drawn up from the soil is released through stoma - called transpiration.

Transpiration is very important in plants, as it one of the processes that allows lifting of water from the soil up the vasculature of the plant (the xylem).  Without transpiration, neither water nor other nutrients would be lifted to the canopy of the tree where they are needed.
Clouds formed by transpiration over the Amazon Rain Forest - from Wikipedia/USGS

Transpiration is a reason why areas with heavy vegetation (forests) tend to be more humid than regions with little vegetation (deserts).  Transpiration can be significant enough to contribute to rainfall.  Transpiration is also tightly regulated, higher in low relative humidity, and higher on warmer days and in higher wind speeds.

Because transpiration is an invisible process, a simple demonstration can help convince yourself that this process is taking place.  Below you see images of an indoor jade plant (Crassula ovata).  This plant is then watered, and has one of its branches covered with a clear plastic bag.  The jade plant is then placed outside on a warm, sunny day.  The bag quickly fills with droplets of water.  This is transpiration in action.

While plants do have a system to regulate how much water they transpire, slowing of transpiration slows the growth of the plant.  This is why a consistent water supply to the roots of the plant is important.  The Groasis Waterboxx is the best way to ensure this consistent supply of water.

A cut away view of the Waterboxx - showing how water is stored, and funneled through a wick to the roots of a growing plant - from 

The Groasis Waterboxx is a self-refilling water battery that provides a consistent source of water to a growing plant.  The Waterboxx contains a water reservoir, filled only once (at setup).  The water is then slowly released through a wick in the base of the Waterboxx, around 50 mL (10 teaspoons) of water per day.  Daily dew and occasional rain refill the Waterboxx.  Because the Groasis Waterboxx delivers water to the growing plant every day, the plant can remain metabolically active and growing, not dependent on irregular rainfall.  The Waterboxx can be removed after about one year and used again.  The Waterboxx can be bought from Dew Harvest in the United States.

If you would like to learn how to grow plants without watering with the Waterboxx, the best resource is the book The Waterboxx Gardener: How to Mimic Nature, Stop Watering, and Start Enjoying Your Garden available here on 

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