Best Bets on TV Tonight

"Smallville" (8 p.m. WB): This is the 100th episode of the show that includes the upsetting death of Superdad Jonathan Kent. Pull out the tissues.
"Landscapers Challenge" (9:30 p.m, Home and Garden): The program focuses on how to add flair to one's yard. It's followed by a new episode of House Hunters at 10.
"Commander Castle" (10 p.m., A & amp;E): Former British cop Paul Castle shares some of his 30 years of experience with local American law enforcement officers. It's a two-part special
"Throwdown with Bobby Flay" (10 p.m., Food Network): The celebrity chef travels the country to challenge culinary standouts -- award-winning bakers, pizza-makers, barbecue grillers and others -- in a series of tension-filled cook-offs in their area of expertise.