The fertile soils, temperate climate and ample rainfall in the American Northeast allows gardeners to cultivate a tremendous variety of plant materials. Not only are beautiful native plants grown, but thousands of ornamental plants from Europe and Asia also have graced landscapes for centuries. You can learn to identify outdoor plants by consulting with plant enthusiasts, using horticultural literature, visiting regional botanical gardens, and taking short courses in botany or plant identification.
Acquaint yourself with other gardeners, nursery and retail garden center staff in your area. Network with people who know plants and take the time to look at plant labels and being learning both common and botanical names. Surrounding yourself with plants and challenging yourself will slowly build your confidence in naming plants and describing plant parts and characteristics.
Purchase horticultural literature that has plenty of photographs to build a reference library. Look for comprehensive books or check out library materials. Field guides are vital to learning Northeastern native plants, while gardening magazines and botanical garden newsletters can share seasonal insight on more exotic plants.
Visit a local or regional botanical garden and arboretum at different times of the year. These public gardens feature--and label with common and botanical names--plants hardy in the Northeast. Well-established examples of gardens to visit include the Arnold Arboretum in Massachusetts, the New York Botanical Garden and Planting Fields Arboretum in the New York metropolitan area, and the Morris Arboretum of the University of Pennsylvania outside Philadelphia.
Contact local community colleges, garden clubs, botanical gardens, regional libraries and learning centers to see if they offer credit and non-credit courses on various plant identification or landscaping topics.
Investigate and peruse what local nurseries and garden centers sell as seasonal inventory. They may have only a fraction of the plants hardy in the Northeast, but the plant materials are labeled and convenient to see. Ask nursery workers about plants hardy in your area or names of plants if labels are missing.