hoop house tomatoes set blooms but no fruit yet

[sfulwood]

i started Rutgers and Brandywine from seeds indoors, the planted into my nominally heated hoop house in feb. i transplanted half into my garden in mid march ( i live in south west tenn.) the tomatoes in the hoop house are 2 or 3 times bigger than the ones i transplanted out into the garden; and absolutely loaded with blooms. Yet my first green tomato showed today 4/18/12 on one of the much smaller plants in the garden.

any ideas on what gives?

thanks for any input.

i'm new to the forum and love all the experience and insight!