Awesome!
Let me know how it goes and feel free to ask if you have any questions, especially directly on the
mysensors thread if it's related to the MySensors part.
I do have a few other projects that I did not publish yet, such as a small CR123 battery operated PCB that will allow the use of up to 3 I2C sensors (ideal for one or two temp+hum Si7021 module and a BH1750 for light level) and run for a couple of years. If you are interested I can send you the files and more infos. I have this on my shelves and it's working flawlessly.
As far as the plants go so far so good, everything is still having a nice coloration etc.
Since last year you have a bunch of new LEDs that came out, from very nice white ones such as used by [MENTION=11565]naoki[/MENTION]
http://www.terraforums.com/showthread.php?t=139997 but also some "7 Wavelength" ones such as on
https://www.aliexpress.com/item/Pla...-1-Blue-440Nm-4-Red-660Nm-3W/32748984587.html that seems pretty promising (but are ~$35 each for a 50W)
If you stick to "full spectrum" LEDs you will probably get something a little less efficient (but probably on par with middle range white LEDs) as they are based on a blue LED + phosphor dye but as it currently runs at ~$9 a piece it's still not bad.