Danny Webber has been out since the start of December. He picked up an his injury when he came on as a substitute in the closing minutes against Coventry at the Ricoh Stadium.
Blackwell said:"I have no doubt that Rob and Danny will give us some real firepower once they are fully fit," said the Blades boss. Rob put his body on the line for the club by coming back before he was physically and mentally ready.
"He (Hulse) thought more about himself than the team. I'm sure he'll benefit from going into the new season fully prepared this time."
Meanwhile according to the Sheffield Telegraph, Ian Bennett has been offered a new contract.