A second reworking. I think I'm getting somewhere.

Looking after leeks

We search for him through the mould on every greenhouse;
we are not sure, but hope for a well-worn man
happiest shooing smut and thrips away.

We have been told to wait for skies to bring him out—
clear after an unpredicted cold snap, perhaps, or shimmering
with an early frost—and wait we do.

Truth be told, he is a man that gets easier as the weather cools
and darkness forces home. Most nights he watches sun-shy leeks grow
slow and useful by the dimming glow of car headlamps.
Collared and watered in, he sits until dawn drowns out the rustle of growth.

It is the same night, the same dawn,
the leeks we eat are blanched like his and yet; and yet.
We have not seen him and do not know his name.