- Herbaceous Ornamentals – NC Extension Gardener Handbook https://content.ces.ncsu.edu/extension-gardener-handbook/10-herbaceous-ornamentals
- Annuals for North Carolina (NCSU Plants Database): https://plants.ces.ncsu.edu/plants/category/annuals/
- Floriculture InfoSearch (NC State Extension) https://hortscans.ces.ncsu.edu/search/floriculture/