Cloudy, rainy days coupled with the shade provided by nearby plants and structures can significantly reduce the amount of radiation available. Plants survive only where the amount is within a specified range. Plants survive only when temperatures allow them to metabolize. Plants differ in ability to survive frost, their responses varying from immediate death to sustained performance. The previous environment and cultural conditions of plants can often shift, but not permanently alter, their tolerance to freezing.
Plants survive only when they are adapted to subfreezing weather.
The thermal cutoff temperature varies widely from species to species. By tradition we group plants into sun, partial sun, and shade types and plant them according to their light and heat tolerances. Gardeners need to know how much water a landscape plant requires in determining its usability in low maintenance landscapes. Rainfall gardening often greatly limits which species can be used successfully. The successful culture of all plant species requires that they be grown in a medium within a definite pH range and with from 10 to 14 essential nutrients in appropriate balance.