A generation ago, the floribundas and climbers of previous generations were considered old-fashioned; hybrid tea roses were "the" garden rose. Today's garden roses come in a wide variety of shapes, colors and growth habits, from the high-maintenance hybrid tea to the tough Wisconsin-bred knockout. Old roses have also been re-discovered; opulent bourbons, sturdy rugosas, ancient damasks and simple species roses fill restored gardens. There are roses for every size garden in almost any climate from the Pacific Northwest to the Deep South.
Look at the way the rose grows; this is its habit. Hybrid teas have long, upright stems bearing one flower at each end. Floribundas are thicker and grow 2 to 3 feet tall with multiple blooms at the end of each branch. Shrub roses grow as wide as they grow tall in a sprawling habit. Miniatures look like tiny floribundas and grow no taller than 2 feet. The old wild or species roses grow low to the ground in a delicate vine-like tangle. Tree roses are rose bushes, often hybrid teas or floribundas, grafted to a long stem and hardy root stock.
Separate really tall roses by habit and woodiness as well as size. Grandifloras grow upright like floribundas but reach heights of 8 to 10 feet. Climbing roses grow tall stiff canes that must be trained to a trellis; their flowers bloom singly or in clusters and they frequently re-bloom through the summer. Ramblers grow long, supple canes that must be supported on the side of a building or a trellis; they bloom once a season in clusters.
Find out when the rose blooms. The oldest garden roses typically bloom once--usually at the beginning of the summer in June. Portland and bourbon roses improved on this by blooming early and then re-blooming in late summer. Today's floribundas, grandifloras and shrub roses bloom throughout the summer.
Note the shape and form of bloom. The antique centifolia rose actually holds 100 petals. Species roses bloom with five petals in a single flower, as do several varieties of knockout roses. Hybrid tea's solitary blooms stand high in their centers with petals that drape back upon themselves as the flower opens. Floribundas and many miniature roses follow the hybrid tea's bloom form. Polyanthas bloom in delicate sprays of little flowers. The David Austin English roses echo the opulent bourbon and cabbage rose in form. Damask, musk, alba and moss roses bloom in single or double open form; their pistils and stamen are visible each flower head's center.
Determine the rose's hardiness. No matter how hardy the root stock, tree roses always need winter protection and succeed best in southern growing zones. Many hybrid teas are also tender and often fail north of USDA growing zone 5 or 6. Shrub roses, miniatures and polyantha roses are often semi-hardy, thriving in areas where the temperatures do not habitually fall below 0 degrees Fahrenheit. Most David Austin English roses are semi-hardy, originating on the Pacific coast. The hardiest roses survive temperatures to 20 below zero; knockouts, many floribundas, rugosas and shrub roses match the hardiness of species roses which survive as far north as zone 2.