There's a ton of answers to your question. It totally depends on you and your grow space Sent from my XT1028 using Grasscity Forum mobile app
True and don't forget a 600 watt hid is probably going to require an exhaust fan to remove the heat. I'm a fan of the 600 watt hid for the 4x4 square's i use. I think a 400 watt will handle two plants no problem but if you can handle the heat issues the 600 will still make the plants grow bigger.
I got two 600 watt Solis tek ballasts dialed down to 400 each/ 800 total above 2 plants in a 2x4....its all about ventilation. I can handle both of them at 600 in there too Sent from my XT1028 using Grasscity Forum mobile app
Right now, assuming they are just a few inches tall, you could set up a 20w CFL a couple of inches above each of them to keep them healthy whilst you sort out your set up. What's your set up going to be? You can grow your plants to any size you want. Figure out the area that you need covering and check out this table a put together a while back. It will give you a rough idea on what lights to use for the size of your area
I'm on my mobile, I tapped the image and saved it to my gallery. If you are on a computer try to right click and save as an image/pdf Sent from my SM-G900V using Tapatalk