Green Grass in the Sidewalk Cracks

Today was over 100 degrees here in Texas. And well the housing division I live in has a yard inspection every Tuesday. Usually every Monday night without fail I mow, edge, and trim the grass and bushes. As well as get all the grass and weeds out of the driveway and road cracks. But this particular day there was a shit load of grass in the cracks. All the way down the road behind my house in the gutterway. And of the damn grass and weeds were effing green. I don't understand that one damn bit. My grass is now turning brown (only in february and april is there much green grass). I know it's summer time with the temps already breaking the 100 degree mark. But the grass in the cracks is the purest green I have ever seen. I have lived in Texas for a while but how in the hell does the grass and weeds in the cracks seem to grow the best? You can't mow this shit all you can do it pull it out with your hands. Shit I hate that grass. I am not able to use any chemicals due to the housing rules. So I guess I'll keep bitching and moaning about it and will continue tearing in out with my hands until I move.