Rovers were unbeaten at home for the first three months of the season before suffering a series of damaging defeats.
Incredibly, the 3-0 defeat of Aston Villa on Tuesday was only the second Premiership win at Ewood since the 7-1 thrashing of West Ham in October.
Souness sees the five remaining home games - starting with Wednesday's crucial clash with fellow strugglers Ipswich - as Rovers' best chance of getting out of trouble.
He said: "If we're going to stay in this league we have got to win our home games.
"We had a massive one on Tuesday and we've got another massive one coming up against Ipswich next Wednesday.
"If we can win our home games and get the odd result away from home, we'll be in this league next season.
"That shouldn't be beyond us because our home form was very good at the start of the season."