Ever since I reseeded my lawn with TTTF year ago, I have had a different grass growing in patches - already present in the soil or perhaps the seed was contaminated. Its appearance is different from the TTTF - it grows shorter, sets seed early, and goes somewhat brown in the heat of summer. The blades are somewhat finer, as well IIRC.

It mostly died during our prolonged drought last year (I went nearly 3 months without needing to mow), leaving patches with 1-2" of thatch, while the TTTF has come through beautifully.

I am starting to see some new growth from the thatch, that I suspect is the odd grass re-emerging. I do not think this is the TTTF spreading into the dead areas (which it will do,

gradually) because the new grass is not attached to runner roots.

Even at this point I see a couple of those clumps setting seed. I don't want it to re-establish in the lawn - I've been (very slowly) cutting the thatch and seeding with TTTF.

Opinions, please!