I have an outdoor vegetable garden in South Florida. The garden consists of things like tomatoes, peppers, lettuce, peas, and squash. Everything was started from seed about 2 months ago. I don't have any veggies yet but plenty of tall stems with leaves all over the place.
It generally never gets below freezing here, but we do have several days during the winter with relatively low overnight lows, ranging from high 30s to low 40s ºF (or 0–5 ºC). Daytime highs after such evenings are typically in the 50s and 60s ºF (or 10–20 ºC).
I'm told I should cover my garden with some plastic or a sheet in order to protect it from the cold. At what point is the temperature low enough (and how long does it have to be expected to be that low) before I need to take the time to do so?