I live in Korat, not too far from Surin, and I plant my tomato seeds around mid to late August, in the grow house where they are protested from the rain. Then, just as the rainy season is abating (early-mid October), I plant them out in the garden. After that, they really just burst with growth. About 2 - 3 weeks after planting the first lot of seeds, I sow a second round. That way, I can extend my growing season well into January and even mid February when temperatures start picking up. Tomatoes here need the cool nights to blossom. When the fruit starts growing, I spray them every 7 to 10 days with wood vinegar to protect them from insects. I also plant insect repelling plants like basil (Italian) or Marigolds to protect from insects.