‘Chill’ could almost be a pleasant euphemism for ‘frost’. Both words describe cool or cold weather that occurs during winter. The obvious difference is that one is good, and one is bad. Chill is a minimum duration of cool weather that some plants require through winter to maintain their schedules. Frost is weather that is cool enough to damage some plants.
This technical difference is that chill is at or below forty-five degrees Fahrenheit (≤45°F), and frost is at or below thirty-two degrees Fahrenheit (≤32°F). That is a difference of only thirteen degrees Fahrenheit (13°F), just above the freezing temperature of water. Climate and weather are simply not cooperative enough to comply to such precise technicalities.
Climates that provide sufficient chill for many plants that require it are also likely to inflict frost on occasion. Where chill is sufficient for most plants that need it, frost is likely much too severe for plants that are sensitive to it. Climates that lack frost are unlikely to provide enough chill for plants that need just a bit. High chill apples and oranges should not mix.
Of course, just as various chill dependent plants require various degrees of chill, various frost sensitive plants tolerate various degrees of frost. Some orange cultivars can survive frost as cold as twenty-five degrees Fahrenheit (25°F) within climates that low chill apple cultivars are happy with. Angel’s trumpet though, succumbs as soon as ice crystals form.
It is helpful to know which plants are sensitive to frost, even in frostless climates. Tropical plants might get rather pallid when the weather is too cool for too long, even if frost is not a direct threat. Potted plants are more susceptible to frost damage than they would be in the ground, but can migrate to sheltered situations. Some can be temporary houseplants.
Frost naturally limits the selection of plants. Various tropical plants that are appropriate to frostless climates are not appropriate for climates with harsh winter weather. That can be confusing with so many distinct climates within such minimal proximity. Coastal, inland, mountain, and all climates are so very different from each other.
This really is something that I did not expect to see. It may not look like much. It is just a raspy anemone with bites taken out of it, blooming later than it should. What is so impressive about it is that it was not planted here last year. It was planted during the previous year, then bloomed on time last year, and then died back like anemones normally do. I did not plant it, of course. It is in a planter where volunteers contribute whatever they like.
We do not get much frost here. This picture of the view through the windshield of one of the work vehicles was taken more than a week ago, while the humidity and the temperatures were still quite low. The sparse and angular pattern of the frost on the windshield is a result of the minimal humidity. There will be more frost later in winter, although there will not be nearly as much as most other climates get.
Where winters are cooler, the deteriorating stems of flowers that bloomed last year either got pruned away already or got knocked down by the weather, and are now rotting on the ground. Around here, where the weather is milder, and some flowers only recently finished blooming, used up flower stalks still stand in stasis. Most but not necessarily all should get pruned out and raked away.
Tony Tomeo 