Posted: 16/07/2012 at 07:46
Producing flowers - hence fruit - is the tomato plant seeking to reproduce itself, to ensure another generation, Lilly. It's much more likely to want to do this if it fears for its future, and it won't fear for its future if it's well-fed and well-watered. It will just lollop along enjoying the comforts. In simple terms it's a matter of creating an environment that causes the plant to think its future is threatened. Tough love, controlled neglect, call it what you like. It won't hurt the plant. Toms are tough, resilient things.
More specifically, over-feeding, particularly with a food high in nitrogen, is one of the major causes of a lack of flowers. Don't feed at all till the first fruit sets. Then, for containters, you don't need to feed more than once a month. Toms aren't "hungry" plants, they don't need to be stuffed full of nutrients. In fact it's bad for them. Plants in the ground - given decent soil to start with - don't need more than three feeds in the entire season.
For containers, let the mix dry out between waterings. Not just now, but always. Keep the plant out of its comfort zone and it will reward you.