Chill can be good. Frost can be bad. The difference is thirteen degrees Fahrenheit. Chill is at or less than forty-five degrees. Frost is at or less than thirty-two degrees. Chill helps some flora to maintain its seasonal schedule. Frost causes some flora to freeze. Both are limiting factors of home gardening. Both are weather patterns that are limited by climate.

Many species from climates with more pronounced seasons rely on chill. They know that it occurs only during winter, and that they should bloom afterwards. Duration of such chill is more important than temperature. Any temperature at or less than forty-five degrees is equally sufficient. Within that, different species require different durations, or ‘chill hours’.

This limits the selection of many species, like various fruit trees. Citrus orchards formerly grew within the San Fernando Valley. They require no chill. Stone fruit orchards formerly grew within the Santa Clara Valley. They require a bit of chill. Pomme fruit orchards grow in the Willamette Valley. Many cultivars of pomme fruit perform best with significant chill.

Frost also limits the selection of many species. Pomme fruits do not mind it. However, if it happens late, it can ruin stone fruit bloom or developing fruit. It might damage citrus trees whenever it happens. Some climates here experience frost annually. Some experience it only rarely or mildly. Several coastal climates experience merely minor chill without frost.

Many garden enthusiasts grow a few species that are vulnerable to frost. Of course, such species are safe within frostless climates. Elsewhere, they may need shelter during cold weather. Potted vegetation may benefit from seasonal relocation. Temporary tenting can shelter imobile vegetation in the ground. Some vegetation is too large to shelter, though.

Vegetation that sustains frost damage is unsightly. However, it is best to delay pruning or grooming until subsequent frost is unlikely. Damaged outer growth insulates undamaged inner growth. Besides, pruning stimulates new and more vulnerable growth. Some types of vegetation should want only superficial grooming. Others might require major pruning.