I have a red one that's about 6-8 months in the tank. When I bought it, it had very tiny leaves. Now, they're about 2 x 3. I have two other red ones that are 6-8 months and 4 months respectively that aren't growing as fast, but still growing. And I have two green ones that are about 4 months in the tank. They are also growing, but not as fast. I don't use co2, and I have 2 watts per gallon, regular aquarium gravel. I also use flourish excel, flourish potassium, and flourish root tabs. I know they're heavy root feeders. Maybe the mulm buildup in my tank (I'm a bit overstocked) is particularly heavy under the big one. I don't vacuum near them for that reason.