In the past I have grown my own tomato plants and have had no problem with getting tomatoes. This year, due to old seeds that grew poorly, I bought a couple of plants, a fantastic, and a small fruited variety. Anyways, the plants are doing great, but I have yet to see fruit on them. There are lots of flowers, but I hardly ever see them fully open. Is this due to the rainy weather, or lack of insects, or what? Thanks for your help.