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Growth:  LED Lights

This page deals with LED lighting and the responses observed. 

The three blooming Plumeria x stenopetala clones, after being moved from the greenhouse into the house, needed a bit of extra light, if they were going to continue to bloom during their time indoors.  As the lab already had two 18" super bright white LED strips which had been used to observe their effects upon plantlets in TC vessels, I only ordered two additional LED strips, both being super bright, one red, one blue, to observe how these would do.  Using a foot candle light meter positioned exactly one foot from the LED array provided for 50 lumens.  In contrast, a second LED array (not shown and encouraging a P. obtusa to grow quickly, now sans mites too) which I constructed a week or so later used newer super bright white LEDs with the same blue and red super bright LED strips provided for a result of 150 lumens, again one foot from the array.  Comparing that to direct sunlight, measured with the same meter (reading taken 12-26-11 under clear skies @ approximately10:30 a.m. p.s.t.), produced a maximum reading of 7,900 lumens (location northern hemisphere, and being just a few days past winter solstice, not all that bright), and neither of the LED arrays are that potent, but are sufficient enough for these purposes.  However, it is most evident that I need to invest in another two sets of super bright white LED strips for these three clones, as the ones from a couple of years ago apparently aren't all that "bright".

Image 12-25-11

Although growth was affected somewhat by the sixspotted spider mite, see mite2011 for details on that, each of these clones have responded somewhat favorably to the light conditions presented by the LEDs.  It should be noted that these lower lumen levels produce leaf tissue which is rather thin and delicate and that results in it rapidly wilting under direct sunlight conditions.  For an example of continued, vigorous growth (if albeit thin for leaves) look at the forming bloom cluster near tip of plant just right of word balloon/pointer which attests to this (plus others on e2 clones which continue to bloom too), a second one for this particular e1 clone this year, and the rather large leaf, which were also observed for the e2 clones, and results in larger leaves than those produced under direct sunlight conditions (eg. sun versus shade leaves).  After re-engineering the LED array (adding two additional super bright white LED strips to the existing four strips, for a total of six) and allowing for growth to occur, another comparison will be done in a similar manner (placement of the plants in direct sunlight for 30 minutes and documentation of lumen level for the reworked array) and images plus information posted.

Image 12-25-11

Those leaves (longer and wider) which were formed under the 50 lumen level LED lighted conditions show wilt after ~30 minutes in direct sunlight, after being watered and with air temperatures in the high 50's (degrees Fahrenheit), these factors would be minimal.  The image was taken after moving into shaded area and just prior to chemical treatment to rid the plants of sixspotted spider mites.  Although the mites do stress them somewhat and may encourage wilting, this still indicates (all leaves formed since indoors wilted and mite populations on these plants were very low) that they will need filtered light conditions during an adjustment period  to get them back outdoors in late spring 2012 without wilting and presumed burning of the tissues which would occur as well, going from previous experiences on other plants.

Image 11-22-11

Showing the first array and composed of two, older versions (2ya), 18" super bright white, one 18" super bright blue, and one 18" super bright red LED light strips all powered by a 12v DC power supply.