Definition - What does Cold Snap mean?
A cold snap is a sudden plunge in temperature that can cause serious damage, even death, to plants left unprotected.
Plants grown outdoors, whether in an in-ground garden, raised bed, or container, are subject to temperature extremes. Many of those can be planned for, but some cannot.
During a cold snap, which is usually unpredictable and does not last long, frost usually forms. Cold snaps seem to occur unexpectedly, with the weather becoming mild again the very next day.
MaximumYield explains Cold Snap
Plants grown outside must contend with temperature fluctuations to at least some extent. This is one reason that gardeners are warned not to plant seeds until a specific number of weeks after the last frost for their area, or to start seeds indoors and then transplant outdoors, or to plant a specific number of weeks before the heat of summer sets in. A cold snap is one example of a temperature extreme that can wreak havoc on a garden.
Really, a cold snap is pretty self-explanatory. It’s a sudden plunge in temperature brought about by a cold front moving through. Generally, these occur during early to mid-spring, depending on your geographic location, and the temperature can go from warm to frigid in a matter of hours. Often, frost forms, which can cause severe damage to plants, even killing many of them outright.
Protecting against a cold snap is relatively simple. The best solution is simply to wait until the chance of a cold snap has passed to plant seedlings outdoors. You can also move potted plants indoors ahead of a cold front. Plants already planted in the ground can be protected with a covering of plastic sheeting, or even old bedsheets placed over the top of them to prevent frost from forming on their tissues.
A cold frame can also be built to provide protection for plants and to lengthen the growing season. Cold-hardy plants can be grown in some instances, as well, although many vegetables are only cold-hardy once mature.