Hugh Silcox of Baltimore still has his 6-foot Norfolk Island palm outdoors and is watching for the first frost: "What's the latest date on which Baltimore had its first frost?" Tough question. The average first frost is Oct. 19-29, depending on your source. The Weather Service will issue frost advisories until Nov. 5, when temperature, wind and clouds make frost likely. After that, the growing season is presumed over, and they don't keep track. Anyone know of a first-frost database for Baltimore?