In my experience, it doesn't always need extra CO2, but it will be much healthier, happier, and easier to grow with it. If you don't want to get a CO2 system (totally worth the expense in my opinion), you could try a dirt tank. When the organics in the dirt break down, they release some CO2. I've seen hairgrass grow in other people's dirt tanks.Does it need additional co2? does it spread out on its own? would one plant in a 29 gal. aquarium be
enough to start it spreading?