So I've done two entries now for roses that would grow in California -- now I'm switching it up, and looking for roses that would survive in Zones 3 or 4. Two I've seen at Longwood Gardens are Rosa rugosa alba and 'Fru Dagmar Hastrup'. The second is also a rugosa, but it only gets to be 4' x 4', smaller than most rugosas. Lots more in the book Rosa Rugosa by Suzanne Verrier. I could swear I also have a copy of her Rosa Gallica around, but I couldn't find it offhand. But Gallicas hardy to Zone 4 include the Apothecary's Rose (Red Rose of Lancaster), its sport 'Rosa Mundi', 'Cardinal de Richelieu', and 'Charles de Mills'. Albas hardy to Zone 4 include the White Rose of York (Rosa x alba 'Semi-Plena'), the Jacobite Rose (Rosa x alba 'Maxima'), 'Celeste' or 'Celestial', 'Mme. Legras de St. Germain' and 'Maiden's Blush'. The Buck roses were bred to survive winters in Iowa, and the Canadian Explorer and Parkland series -- yes, you guessed it. More about Buck roses and hardy Canadian roses at www.heirloomroses.com.
Common lilacs are extremely hardy. Butterfly bush will freeze to the ground in Chicago, but then grow back from the roots -- so I've read. Most daffodils are quite hardy, and of course little bulbs like snowdrops and crocus. Some irises are notably hardy -- I'm guessing Siberian iris would be in that category.
More tomorrow, once I finish reading through Tough Plants for Northern Gardens by Felder Rushing. I'll put what's hardy here in Zone 6, for what it's worth. And there are plenty of colorful annuals anyone can grow for the spring and summer, and that will give good color until the first frost.