hfp777:
This is a cheap DIY endeavour, it's to grow parsley and chive. How many watts are enough for that you reckon?
In your link it is not clear whether it's a mix of red orange blue white LEDs or purple LEDs?
It's everything but green. Plants reflect green light -- that's why they look green.
The reason why they're using a mix of red/blue/orange is because they think they can get more useful lumens/watt than a white LED (which wastes some power creating green light in its mix). When you're burning hundreds of watts of power in a greenhouse you start looking at getting the most bang for your buck, but if you're just lighting a few sprigs of herbs then that approach is a bit overkill.
So you could trying mixing blue/red/orange with the satisfaction that you're saving a few pennies a year, and you might even save enough power to justify the higher market price of blue/red/orange LEDs ;). I'd suggest a cool white LED and be done with it.