Experiment Summary

8/21/17 - Data logger and sensors installed in Shade-house

8/28/17 - Plant sleeved and placed in a dark airconditioned room

9/1/17 - Plant un-sleeved and moved into a naturally and artificially lit office.

10/20/17 - First date the plant was watered inside the office.

11/1/17 - Water applied

11/20/17 - Water applied

12/8/17 - Water applied

12/15/17 - Experiment End

     This is a summary of an experiment measuring the water volume content and water use of a 14" Marginata Cutback as it transitions from shade-house to interior environment.  The purpose of the experiment is to illustrate the transition, in water use, of an interior plant as it moves from a highly volatile exterior environment to a less demanding more regulated interior environment.   Plants from South Florida, especially those shipped between June and October, can arrive with substantial water in the soil.  Further, drought conditions are easily corrected with the addition of water and with minimal damage to the plant, whereas saturated conditions can lead to root death or disease.  Root death/loss is difficult to correct and can reduce the appearance of the plant below acceptable levels.  The findings from this experiment should help to develop a watering schedule that is the most beneficial for plants making the transition from a nursery in South Florida to an interior environment elsewhere in the country.  

        We used a data logger, that records measurements every 15 minutes, to record the "Percent Volume Water Content" at two different locations in the soil column for the period beginning August 21, 2017 and ending December 15, 2017.  During this period, the plant was located in the shade-house for one week, then a dark, air conditioned room inside a sleeve for 4 days, to simulate shipping, and finally installed in our office for the remaining 105 days.  After removal from the shade-house, no water was given to the plant for 53 days.  Afterwards, water was applied as needed based on the appearance of the plant.  Watering dates inside the office were 10/20/17, 11/1/17, 11/20/17, 12/8/17.  Intervals between the watering were 12, 19 and 18 days.  All irrigation water used in the office environment contained a soil wetting agent in order to gain the maximum effect and longevity from each watering.  The appearance of the plant after 105 days is very similar to it's appearance in the shade-house, and well within acceptable limits for an interior plant.  No additional additives, chemicals or treatments were applied during the experiment.  Pictures of the plant at different stages of the experiment are shown towards the bottom.

Soil Water Content Graph

The percent volume water content is defined as the ratio of the volume of water in a given volume of soil to the total soil volume.  At soil saturation,  the percent VWC will equal the percent of pore space in the soil.  Pore space for a volume of soil is the spaces that will hold air and water in between the soil particles.  The soil this Marginata is growing in has a total porosity around 60%.  If this soil were completely saturated the %VWC would read 60%.  In the graph below you can see the peak VWC measurement to be about 26%.  Rather than the individual values the focus of the experiment is to show the trend over time and change of environment compared with the physical appearance of the plant.  

   The first section of the graph shows irrigation and rain influence which increase the %VWC and also the transpiration, evaporation and drainage effects that lower the %VWC. Once the plant is removed from the shade-house, the curve begins to level off since it's environment has become much more stable.  Over time a very gradual decline in %VWC is seen until 10/20/17 where the lower soil probe shows only about 2.2 %VWC.  That is only 2.2% of the soil volume is water.  The picture of the plant corresponding to this level is below with the date 10/20/17.  At this point I can start to see some indication that the plant needs water, but it is before any yellow leaves or leaf drop.  This plant spent 50 days in the office without any damage due to water deprivation.  

Figure 1.  Graph of the %VWC for the Experiment Period up to and just after the first time the plant was watered.

Figure 2.  Graph of the %VWC for the entire experiment period.  Shows the 4 times the plant was watered in the office.

The graph below, shows the other metrics that the data probe collected during this period.  PAR,(Photosynthetically Active Radiation), air temperature and soil temperature are displayed without the %VWC measurements.  PAR light was much higher when the plant was in the shadehouse compared to the office environment.  The temperature probes show a regular repeated  fluctuation associated with the air conditioning cycles.  The soil temperature fluctuates less severely than the air temperature.

Figure 3. Graph of PAR Light, Air Temperature and Soil Temperature

Figure 6. Test Marginata after 15 Days in Office.  17 Days Since Last Irrigation.		Figure 7. Test Marginata after 34 Days in Office.  36 Days Since Last Irrigation.

Figure 8. Test Marginata before First Irrigation in office.		Figure 9. Test Marginata on last day of test.  4 irrigations total from 8/28/17 to 12/15/17