A hearty brew of Kryptonite and good ol' family values is powering The WB to its best season ever.

With shows like Smallville, Everwood, Gilmore Girls and old warhorse 7th Heaven, the WB's audience has ballooned by almost 28 percent this season -- an increase of more than 1 million viewers a night from last season.

That's better than any of the big boys, including CBS -- the only other major broadcaster to show an improvement over last year (about 11 percent in total viewers).

"Your baby is always the prettiest in the hospital, so when we put the schedule on the board last May, I felt the best about our fall schedule," WB president and COO Jed Patrick told The Post yesterday.

"Things are leaping right and left at the WB," said industry analyst Marc Berman of Mediaweek.

That's a major achievement in a fall season where NBC (down 4 percent), ABC (down 8 percent) and UPN (down 24 percent) are hemorrhaging viewers.

Fox, which has yet to launch most of its fall season because of Major League Baseball coverage, is up 19 percent over last year.

With Everwood, the WB has, for the first time in its seven-year history, managed to find a compatible show to follow its highest-rated drama, Monday's family friendly 7th Heaven.

In the past, shows that followed 7th Heaven could lose as much as half of that show's viewers, whereas Everwood -- with an average audience of 6.1 million -- loses only about 6 or 7 percent.

The network is also banking on Birds of Prey -- a girrrl-power spinoff of Batman that premiered last week with decent ratings.

As luck would have it, the WB scored last year when it launched Smallville -- the hit show about teenage Superman, Clark Kent -- and Gilmore Girls, one of the most critically praised dramas on TV.

Both shows are drawing more viewers than they did last year on Tuesdays -- even though The WB had to reprogram the night after losing its signature show, Buffy the Vampire Slayer, to UPN.

"Last year they planted the seeds," Berman says. "And this year [the seeds] grew."

The WB's third engine this year is its Sunday night combination of veteran supernatural dramas Charmed and Angel which appear to be doing well -- at least until Fox launches the 14th season of The Simpsons next month.

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