Why do my frozen vegetables taste horrible?

I was so proud last summer, buying up farmer's market produce, chopping and freezing the bounty for the winter. Well phooey. The broccoli and cauliflower taste horrible -- inedible -- and I don't know what happened! I didn't blanch them, because I read in several places that you didn't need to. Could this be the cause? I just chopped them up and put them in freezer bags, removing as much air as possible with a tiny straw. Now my green beans, which I did blanch, are wonderful. (And I also discovered the best way to cook them, for me at least, is to quickly saute them in olive oil with lots of kosher salt. They don't get as soggy as when you steam them.) Haven't tried the onions yet. It's so discouraging, particularly this week when I'm snowbound and lacking in produce.

Any expert opinions out there?