Separate Power Source for Relay Board?

I am a total noob and starting my first arduino project so please forgive my inexperience.

The project is going to be a hydroponics system using a 4 channel relay board to control pumps, lights etc. The elements that will be connected to the relay are somewhat "higher" wattage. I will be using a 600w grow light as well as an 800w air conditioner and i'm concerned with how to actually power the relay board. Does the 5v coming from the arduino board to the relay board have enough power to actually run all 4 relays at once, or should I be using an external power source of some sort to power the relays?

As I mentioned before I am a bit green in this area so any other helpful information you may want to share relating to the topic will be greatly appreciated.

Depends on the relays.

I'm actually not even sure what to look for in a relay. What do you mean when you say it depends on the relays? Can the arduino handle powering these items in any situation?

I'm actually not even sure what to look for in a relay.

Coil resistance. Relays draw current. If the amount of current they draw exceeds the amount of current the 5V source on the Arduino provides less the current requirements of the Arduino itself and any other connected devices, then you'll need external power.

Ahhh gotcha. Makes sense. Thanks for clarifying that!

I have used stuff like this - it will have separate power supply for relays and is isolated from arduino:

You can get thes in groups of 1,2,4 and 8 relays

The other thing to look into is the voltage and current requirements of the devices you are connecting. Then look for appropriate relays. You'll probably need to look for 12VDC drive relays for the devices you want to run, since they are likely to run off 120 or 240VAC. Then you will need a separate supply.

this might be of some help: