from scratch
if you start something from scratch, you begin it without using anything that existed or was prepared before

[TahlilGaran] Dictionary of Contemporary English ▲

from scratch
from nothing.
We decided to build a newspaper pretty much from scratch.

Usage notes: often used in the form start from scratch:
Can we fix the current computer system, or would it be better to start from scratch?

[TahlilGaran] English Idioms Dictionary ▲

from scratch
from the very beginning
He decided to build the house from scratch.

[TahlilGaran] English Idioms Dictionary ▲

from scratch
adv. phr., informal With no help from anything done before; from the beginning; from nothing.
Dick built a radio from scratch.
In sewing class, Mary already knew how to sew a little, but Jane had to start from scratch.
Compare: FROM THE GROUND UP.

[TahlilGaran] English Idioms Dictionary ▲