> Select G.GERM from Germination G
> PLAN (G ORDER I_GERMINATION_DATE_DESC)

You might try
Select G.GERM from Germination G
PLAN (G ORDER I_GERMINATION_DATE_DESC DESC)

> Select G.GERM from Germination G order by G.GERM_DATE Desc

If you look closely at your example you will see there is no "_" between
the GERM_DATE and Desc.