Well even in the winter the sun still comes out which is why you might have success, also co2
is the air is 400x that of a non pressurized co2
aquarium, yes I agree on leaving stuff alone but in your case it is probably a result of the abundance of co2
and sun, I couldn't even grow crypt parva in my tank.
On a side note though to much par in a lightly planted tank with high Nutrients = algae