Goode landed awkwardly on his ankle during the 3-2 victory over Bradford City and suffered ligament damage as a result.
Alexander said: “Charlie unfortunately is going to miss the rest of the season as he’s damaged he’s damaged his ankle ligaments so we won’t see him back fit with us until pre-season.
“It’s a real difficult one for us and it was a freak injury really. He’s gone up for a header, landed awkwardly and he’s a big lad so there’s a lot of force going through that ankle when he landed wrongly. It’s bad news for Charlie and for us.
“He’s going to be doing a lot of work over the summer and pre-season is so vital for players, so we want him to be back for that. He’s a dedicated lad so he will work really hard.”
“He trains magnificently and he’s always ready to play. We’ve missed a number of big players this season and still managed to pick up results, so we’re going to have to do the same without him.”