Exactly that. It is the date by which the last frost occurs in the Spring, on average. So for the Salt Lake area, that date is around Mother's Day or May 10. The average last frost date is important because you want to wait until danger of frost is past before you plant your warm-season, tender plants. The nurseries are loaded right now with plants like basil, tomatoes, impatiens, geraniums and squash plants. Don't be tempted!! If you were to plant tender plants too early they could be killed by low temperatures (28 degrees F). Ask your gardening neighbors about the frost dates in your neighborhood because they can
vary, depending on where you are.