Brigitte,

I planted 3 lavender plants in my yard back in early spring. They look
healthy, but they aren't growing much, and they aren't putting out any of
the lavendar flowers. Two are in full sun and one is in part sun/part
shade, but they all look the same.

What you need is patience...
My lavender had to stand a cold winter before blooming and growing fast this
year (I'm in zone 6). I'm not sure whether it'll survive in zone 5 (oh, a
rhyme, a rhyme!), you may need a bit of protection in winter. But I'm sure
it'll bloom next year then.

Best wishes
Gaby

--
Mrs. Gaby Chaudry
http://www.gaby.de/bilder/