I agree with Melissa completely. Growling can be playful, it can be talking or it can be a warning. It should NEVER be discouraged because it gives you information. But if you can't tell the difference between the kinds of growl, you really need to get a good, positive based trainer in there to help you figure out what's going on, and how to address it in each circumstance.
Kodi and Panda both "talk" in a way that can sound "growly" but it isn't. Panda does it when she wants to be picked up. Kodi does it just "conversationally". LOL! Kodi will ALSO growl when he has something and doesn't want either a person or another dog to take it away from him. But it has a COMPLETELY different tone than the "conversational" growls he does. It is clearly a warning. If it is a toy or food, I honor it, and expect the other dogs to honor it too. I don't think he should have to share if he doesn't want to. If he has something he shouldn't, (he's a terrible paper thief) I put my hand out, and in a quiet voice, I say, "Give!" he growls a bit more, in a grumpy undertone, then comes and SPITS it into my hand with one more grump. BUT, that part took a LOT of training, and I ALWAYS reward him for giving me something he wants to keep. He knows the routine of "running to the kitchen" to get his cookie for giving up contraband.
One thing that is REALLY important is that you never, EVER want to punish a dog for growling. That is the "early warning system" for the dog to let you know they are unhappy with something. Dogs that learn that they are not allowed to growl are the ones that end up "biting without warning"... because HUMANS have taken their ability to "warn" away. It is really important that all family members remember that a dog has feelings and needs too. If they don't want to be picked up or handed off to a different person, you should try to figure out what's bothering them about that action and work on making them feel more comfortable with it.
When they are younger, it can help to have a cookie in your hand to "trade" for the item you need to get from them.