Tomato Plants Lack Flowers and Fruit
For years I have been growing tomato plants and giving them away to family and friends. Last year they all did great except for my cousin's in Michigan. The plants were big and beautiful but had no flowers or fruit.
Your cousin may have been too kind to his plants. Too much nitrogen fertilizer can reduce or eliminate fruit production. Encourage him to have his soil tested so he knows what type and how much fertilizer to give his plants. Weather can also cause poor fruit set and development. The plants bloom but fail to develop fruit when night temperatures drop below 55 or the day temperatures rise above 95 degrees. The blossoms start to persist and fruit develops once the temperatures move back to normal.