De or het groenharing?

The correct Dutch article is:

de groenharing

Rule Words ending in -ing: almost always de. See the rule

How to use groenharing

the groenharingde groenharing
this groenharingdeze groenharing
that groenharingdie groenharing
our groenharingonze groenharing
your groenharingjouw groenharing
every groenharingelke groenharing
which groenharing?welke groenharing?
a big groenharing / the big groenharingeen grote groenharing, de grote groenharing