Designing color into cold-climate gardens can be challenging; you need plants that will survive harsh winters, and a plan for a colorful off-season, i.e., winter. If you're in a cold USDA zone, you're going to have an off-season, and it's probably a long one.
Luckily, there are genera that don't just tolerate the cold, but prefer it. We frequently get questions from people who have moved south and wonder why they can't find lilacs. Syringa likes the cold, and needs winter chilling to flower in spring. Lilacs will grow well in colder zones, and newer reblooming varieties, like the Bloomerang® series, will flower in summer even if the spring buds are damaged by erratic late-winter weather.
Reblooming versions of familiar plants are a good addition to the cold-climate landscape palette. We're all familiar with plants that grow happily yet don't flower. A late winter warm-up followed by a plunge in temperatures can damage flower buds. Plants that flower on new wood as well as old provide a second opportunity for garden flowers.
In addition to lilacs, there are now reblooming Weigela, such as the Sonic Bloom® series, the non-invasive Lo & Behold® series of Buddleia and the Let's Dance® series of Hydrangea macrophylla. Just remember that if the traditional species isn't hardy in your area, the reblooming one won't be either. Remontant (reblooming) plants simply give cold-climate gardeners a second chance at flowering.
Spiraea in particular has a lot to offer landscapers. Durable and deer-resistant, it's available in a wide range of colors and sizes. Newer varieties have intense color, including orange or even red spring foliage. Flower color has intensified, too, with some varieties having carmine-red buds and cranberry-red flowers. The new Double Play Doozie® spirea is a sterile variety, so it reblooms without shearing, making it an extra attractive choice. Those who want a more subdued color palette will appreciate the cool blue-green foliage and white flowers of other new cultivars.
Plant breeders have released colorful new selections of genera that typically aren't very flashy. New introductions of Diervilla in the three-color Kodiak® series combine durability and adaptability with colorful foliage. When designing with leaf color in mind, it's important to realize that the color will typically be more vibrant in full sun than in shade.
Evergreens are an obvious choice, but interesting bark like that of bright red Cornus stolonifera or exfoliating Physocarpus is very appealing, too. So are the flowers of Hydrangea paniculata and Hydrangea arborescens when left to dry on the plant.
When designing in colder areas, try to think of all the things you can grow instead of the things you can't. There are some snowbirds in Florida who would love to enjoy the lilacs you take for granted.
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