how about using maybe two servo motors to control one strong light source. Then a microcontroller could move the light in a certain wanted pattern over the plants and repeat periodically, also then maybe use pwm to fire short burts of light.
Perhaps slowing the shimmer effect down, and decreasing the multiplier of "magnification" would be better for land plants? Sort of like a cloudy day versus an overly sunny one.
No clue, just throwing an idea out there. I do, however, like to think that plants might enjoy a flat out sprint for relatively short bursts, then a jog/walk afterwards. It's an interesting idea that might lead to higher gram/kWh ratios.