Purgeth
means,
To Cleanse: specifically, to prune.
In the garden, 'pruning' is a very important activity.  There are several reasons for
pruning, such as to: correct or repair
damage; shape; train; encourage flower and
fruit production; create a pleasing form;
bring roots and leaves into balance;
thin out dense growth to let in light
and air; etc.  Our Father, the
Master Gardener, knows just
how, and when, all of
His 'branches'
need  
pruning.  
I am the true Vine,
and my Father is the husbandman.
Every branch in me that beareth not fruit
He taketh away:
and every branch that beareth fruit,
He purgeth it,
that it may bring forth more fruit


John 15:1-2