Depends what kind of rhubarb it is. Some kinds never turn red. I have a huge green rhubarb in my yard. It makes great relish and chutney. If you're using green rhubarb in a pie or crisp, just add a couple extra tablespoons of sugar to the recipe and it will taste great! I make stawberry-rhubarb crisps with mine all the time.

Don't pull it, just cut the stalks off at the bottom, close to the dirt. It will grow a new crop that way.

Also keep the leaves away from your dogs. Rhubarb leaves are toxic to dogs, the stalks are safe.