Luckily, most perennial varieties will easily survive these temperatures. In fact, all those species, cultivars and hybrids that are cold hardy to USDA hardiness zone 9 or below! But in colder areas, temperatures can drop to much lower depths, like -40oF (which is also -40oC), and even below. And this is why we have selected very cold hardy varieties of perennials for you, from USDA zone 4 (or 5 in one case) to 2.
1: Hellebore (Helleborus spp.)
And in fact, hellebore is the little queen of winter gardens! Not only is it very cold hardy, but it actually likes cool temperatures, and most of its many varieties will be in full bloom during the winter months!
2: Snowdrop (Galanthus nivalis)
Could we forget snowdrop, a bulbous perennial with a winter inspired name, from our list? Certainly not, especially because it will survive temperatures that drop to a super freezing -40oF (or -40oC)!
3: Garden Phlox (Phlox paniculata)
Famous for its heavenly fragrance, garden phlox will also survive ice cold temperatures of -40oF (or -40oC)! Rich in nectar, its flowers will blossom when winter has fully gone though, in during the hot summer months, and they will attract lots of pollinators and even hummingbirds!
4: Horned Violet (Viola cornuta)
Most violet varieties are really cold hardy, but if you want a large, showy pansy, then the “horned” species and its cultivars will offer your garden a great perennial that will survive temperatures as low as -20oF (or -28.9oC).
5: Poet’s Daffodil (Narcissus poeticus var. recurvus)
All daffodils will survive temperatures as low as -20oF (or -28.9oC), so, pick your own, but I would like to focus on a very special species: poet’s daffodil… And this is not only because Narcissus poeticus var. recurvushas a very evocative name… No, it will also grow in USDA zone 3, where winters can see the thermometer fall to a freezing -40oF (or -40oC)!
6: Columbine (Aquilegia caerulea)
Native to Colorado, Montana, New Mexico, Wyoming and Utah, Aquilegia caeruleais a columbine variety that can withstand temperatures far below freezing, -40oF (or -40oC), in fact!
7: Chinese Ground Orchid (Bletilla striata)
No, it is not a nickname, Bletilla striata is real orchid species native to China, Japan and Tibet! And it will survive in your garden even if winters see temperatures as severe as -20oF (or -28.9oF)!
8: Daylily (Hemerocallis spp.)
To prove yet again that the fact that you live in a region where winters are freezing does not mean that you need to renounce super showy, even exotic flowers… Enter daylily, or Hemericallis!
9: ‘Purple Emperor’ Stonecrop (Sedum telephium ‘Purple Emperor’)
Now, I am going to surprise you! You don’t expect succulents to tolerate cold temperatures, but some, like hens and chicks (Sempervivum spp.) and yucca, manage USDA zone 5, but the hardiest of all must be stonecrop, which can grow in USDA zone 3, where winters can see the thermometer drop to -40oF (and -40oC)!
10: Plantain Lily (Hosta spp.)
Plantain lily, or simply Hosta, is a favorite perennial, especially in shady gardens, and it really likes fresh air. Actually, it is very cold hardy, despite its soft and tender personality, as it can resist temperaturesfar below freezing: -40oF, or -40oC!
11: Bearded Iris (Iris germanica)
One of the most showy iris types (or species) in the world, bearded iris is also very, very cold hardy indeed! In fact, it can survive in temperatures that drop to a freezing -40oF, or -40oC, and you can grow it in the coldest regions of the USA or virtually in the whole of Canada!
12: Crocus (Crocus spp.)
Here is another bulbous perennial that can survive temperatures to make your teeth chatter, -40oF (or -40oC), and a garden favorite: the little crocus.
13: ‘Black Princess’ Hardy Water Lily (Nymphaea ‘Black Princess’)
We think of water lilies as tropical perennials, but there are hardy ones as well, and we picked an exceptional one for you: ‘Black Princess’. It is hard to believe looking at it, but it will tolerate extreme temperatures as low as -40oF (or -40oC)!
14: Lily of the Valley (Convallaria majalis)
You can literally grow lily of the valley even in the coldest regions of Canada and the USA, in fact, anywhere where you can grow a plant that’s not a lichen… It will tolerate temperatures to daunt a mammoth, in fact, as low as -50oF (or -45.6oC)!
15: Bushy Aster (Aster dumosus)
Most aster types are cold hardy, including the popular New England species (Aster novae-angliae), to USDA zone 5, but A. dumosuswill tolerate even colder temperatures, to -30oF (or -34.4oC).
16: Martagon Lily (Lilium martagon)
Sun loving, showy, iconic and with an exotic look, real lilies (Lilium spp.) can be quite cold hardy indeed. So, for example, Asiatic, oriental and orienpetvarieties will grow in USDA zone 4, while even trumpet ones can survive in USDA zone 5.
17: Tulips (Tulipa spp.)
In fact, if you live in a country where winters are cold, you may even count yourself lucky! Yes, because tulips actually like it!
18: Blanket Flower (Gaillardia spp.)
But if you really want to bring the colors of Mexico to your garden in a cold region, blanket flower is the perfect perennial for you! Native to both North and South America, this plant expresses the heat, even sultry sunlight of hot countries, with bright reds, yellows and oranges!
19: Evergreen Candytuft (Iberis sempervirens)
If instead you want to prolong the mantle of snow effect even when it has finally thawed, a lovely frost tolerant perennial from southern Europe will help you achieve this in your garden: turn to the evergreen candytuft. Cold hardy to USDA zone 3 (which is -40oF, or -40oC), this low and sprawling plant will start early in the season with its candid floral display.
20: Glory of the Snow (Chionodoxa spp.)
It seems natural to conclude our list of frost tolerant perennials with the little bulbous glory of the snow, which tolerates temperatures as low as freezing -40oF (and -40oC). And it will blossom early in the season, even if your garden is still covered in the white coat of winter
