When a gardener comes to me and asks for a continual-blooming, hardy white or off-white rose, the first rose that comes to my mind is the Canadian rose 'Morden Blush'. This white/blushed-pink rose has provided color in my landscape for over 10 years, and although it blooms in the shadow of a taller Zephirine Drouhin, it still manages to never be out of flower during what passes for spring, summer, and fall in the Flint Hills.
'Morden Blush' was introduced by Collicut in 1988 as one of the Parkland Series bred at the Morden Research Station in Manitoba. According to one report, she has been voted as the favorite Canadian shrub rose by the Canadian Rose Society, but I cannot find a reliable source to confirm that award. One Internet site describes 'Morden Blush' as "shy," and I believe that an apt adjective for her. 'Morden Blush' stays well-refined, perhaps 3 feet high and 2.5 feet wide in my garden, unlike her rampant Explorer series cousins. Both her blush pink color and her soft scent add to her demure allure.
Despite her non-vigorous nature however, she is completely hardy, with no die-back here in Zone 5b and she is reportedly hardy to Zone 3 with some tip-kill there. She is heat-tolerant as well, blooming and keeping good flower form throughout the worst of the Kansas summers and several writers suggested she is tolerant of MidWestern alkaline soil. She blooms as vigorously as any rose I grow. The very double blooms come 5 or so to a cluster, and open white with a pink center, fading to an ivory pink as they age. They repeat continually here Kansas and are listed at 12.3 weeks of annual bloom by Ogilvie and Arnold, the most prolific of the Morden group. I view this rose as a "cutting rose" and she lasts well sitting in a vase on the kitchen table.
The only deficit I can ascribe to this rose is that her glossy deep green foliage is moderately prone to blackspot in my garden. I don't know if it is because she grows in the shadow of taller Zephirine and Prairie Joy and surrounded by daylilies, or if it just her nature to be easily diseased, but I use this rose as a blackspot indicator for my garden and start spraying my few susceptible roses when I see "Morden Blush' begin to lose her hemline. In fact, she is susceptible enough to blackspot that she'll sometimes can end up completely naked in my garden by Fall if I don't keep an eye on her, hardly a proper finish for such a coy beauty.