A lighting device for supporting plant-growth includes an LED driver thatinputs a high-voltageAC driver-input current. The driver outputs a driver-output current at astepped driver-outputvoltage. LEDs are powered by the driver-output current. The LEDs include deep-redLEDs that output a first number W1 of radiation watts of a deep-red light bandat 660 nm, farredLEDs that output a second number W2 of radiation watts of a far-red light bandat 730 nm,and white-light LEDs that output a third number W3 of radiation watts of whitelight having acolor rendering index (CRI) of less than 75. W3 is greater than the sum L1+L2. At least 3%of all radiation output by the LEDs is at or above 700 nm.
