De or het beekbedding?

The correct Dutch article is:

de beekbedding

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

How to use beekbedding

the beekbeddingde beekbedding
this beekbeddingdeze beekbedding
that beekbeddingdie beekbedding
our beekbeddingonze beekbedding
your beekbeddingjouw beekbedding
every beekbeddingelke beekbedding
which beekbedding?welke beekbedding?
a big beekbedding / the big beekbeddingeen grote beekbedding, de grote beekbedding