I found a script that you can put into your plants or anything and set it to just light up at night time there are a few options you can play with % of light glow or colour in this example I have it set to 50% light no glow Cycle on time=50%
only 10 lindens here is the link https://marketplace.secondlife.com/p/Light-Glow-Script-Auto-Onoff-Automatic-Light-with-daynight-sensor-V1/13868616