If all you want to do is control the lights, get a timer from Amazon that is built to do that. Unless you are making sure to match your amp draw with an appropriate relay that can handle it, then the draw could melt your system when you have lights running, and whatever else you are looking to control. Otherwise the R PI is a bit overkill.

NOW! if you want to create an entire control system, and build out some of those GPIOs to run a temperature sensor, water pump, humidity, and moisture sensor, NOW YOU ARE PUTTING THE PI TO USE. BUT, don’t bother taking the time to write it yourself, unless you want to learn programming, there are some versions on GIT that you can pull down to start from at the least.
I have contemplated doing something like this, but I want to be a permanent place to do something like that.

Can you link one? I agree not everyone has spare R Pi laying around, but I’m not aware of anything operating on a 20 hr base cycle. And R Pi can control everything, not just lights

Can’t post the links(?), I keep getting an error, but all I did was search google for raspberry pi garden controller. Github has the GardenPI source available, as well as piGarden, Pigrow, and GardenPIO. The project on Instructables shows the components, wiring, and build, along with video on youtube.

Right on, for some reason I only saw the first half of your comment. I would totally go to github first, but have written some clock managing code that I think could be modified to reduce everything from a 24 hr day down to 20 if needed. I was only commenting on the light because that’s what the guys mentioned in the video but in the back of my mind the gears were turning. Change the light you change everything.