Evergreens are plants that retain their foliage and color year-round. Juniper is an example. Cell packs are containers are that hold four or six stock plants. Flats are containers that hold cell packs. Herbaceous plants are those liking woody stems, some may die in the winter and return in the spring.
Perennials are plants that live more than two seasons.
Catnip and thyme are good examples. Propagation is reproduction that is deliberately controlled or manipulated. Methods include cuttings, seeding, plugging, grafting and layering. Root substrate, or root medium, is basically the type of soil you use. Specimen plants are those with unusual distinction and colors or shapes.