If your LED Grow light is dimmable, you can let the controller do the dimming (and switching) for you.
The system turns the light off by dimming all the way to zero.
If you don’t have a dimmable LED, you can still connect the light, please read here.
If your light is dimmable:
The Controller has a 6-pin connector. Many grow lights use these for dimming.
If your light has that, you can connect via this cable.
Different brands use different polarities in their cables. So you would switch the controller’s cable polarity in the settings of the controller.
My LED has no 6-Pin dimmer cable connector 
Well, that’s ok. You may only have a knob to dim the light.
You can still connect it to the controller with this adapter cable.
You may need to do a little bit of DIY cable work tho I’m afraid. Nothing major.
On your LED, cut the cable between dimmer-knob and driver. Then screw your dimmer cable into our adapter cable.
For questions as always, please post here in the forum.