Hardy Annuals

• Hardy annuals are cold-tolerant species that can survive frost and freezing weather. According to North Carolina State University, hardy annuals can be planted in the winter or spring before the last frost. Hardy annuals include plants such as pansies, viola and foxglove.
  
  

Half-hardy Annuals

• Half-hardy annuals tolerate cool, wet periods in home gardens but should be protected from frost. Plant half-hardy annuals such as forget-me-nots, strawflower and blue sage as soon as the risk of frost has passed.
  
  

Tropical Annuals

• Tropical annuals are highly sensitive to soil temperature and will not survive when planted in soils below 60 degrees Fahrenheit. Wait at least three weeks after the last frost to plant tropical annual seeds in your garden for best results. Colorful tropical annual species include begonias, marigolds, zinnias and petunias.