Answer: I know it's difficult to find your zone when your elevation is high, so your best choices of plants are those that are hardy to zero degrees and below. Any plant hardy in USDA zones 1-6 would grow well in your landscape. Here's a list of plants suitable for USDA zones 1-6:
Dwarf birch; Crowberry; Quaking aspen; Pennsylvannia cinquefoil; Lapland rhododendron; Netleaf willow; Paper birch; Bunchberry dogwood; Silverberry; Eastern larch; Bush cinquefoil; American cranberry bush; Japanese bayberry; Russian olive;
Common juniper; Tartarian honeysuckle; Siberian crabapple; American arborvitae; Sugar maple; Panicle hydrangea; Chinese juniper; Amur River privet; Virginia creeper; Vanhoutte spirea; Flowering dogwood; Slender deutzia; Common privet;
Boston ivy; Japanese rose; Japanese yew; Japanese maple; Common box; Winter creeper; American holly. With these suggestions as the backbone of your landscape, you can use perennials and seasonal annuals to bring color to your garden.
Hardy perennials include daylily, stargazer lily, gay feather, hosta, bellflower, pennstemon, obedient plant, coneflower, peony, poppies, aster, delphinium, coral bells, salvia, globe thistle, hollyhock, bleeding heart, primrose, columbine, pinks, basket of gold, coreopsis, campanula, monarda, scabiosa, phlox, forget me nots, and hardy carnations. Fill in with either cool season or warm season annuals (depending upon season!), and you'll have an attractive garden. When looking at unfamiliar plants, try to find those with "Siberian" on the plant label and you know they survive even the coldest winters. Some examples include:
Siberian Iris (Iris sibirica), Siberian tea (Bergenia crassifolia), Honeyberries (Lonicera kamchatika), Achillea sibirica ssp. camtschatica, Siberian squill (Scilla sibirica), Siberian dogwood (Cornus alba sibirica), Siberian bugloss (Brunnera macrophylla), Siberian Miner's lettuce (Claytonia sibirica), Siberian Primrose (Primula siberica), Siberian columbine (Aquilegia glandulosa), Siberian foxglove (Digitalis sibirica), Siberian Solomon's Seal (Polygonatum sibiricum), Siberian Globeflower (Trollius ircuticus), Siberian Bellflower (Campanula sibirica), Siberian Lily (Lilium pumilum), Nepeta sibirica, etc.
Hope these hints help you find just the right plants for your landscape!
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