Rugosas and the Canadian Explorer roses usually come through a New Hampshire winter without protection, because most are rated for zone 3 or colder. Knock Out and New Dawn are rated for zone 5, which covers the milder south but not the North Country. Hybrid teas, tree roses and most grafted garden-center stock need a soil mound and some luck. Below, named roses are sorted into those groups. For basic planting and care, see growing roses in New Hampshire.
Which roses survive a New Hampshire winter
The USDA Plant Hardiness Zone Map puts the state anywhere from zone 3b to 6a. That is a wide spread for one small state. The map is built on a single number, the average annual extreme minimum temperature, so it says how cold the worst night of a typical winter gets and nothing about snow cover, wind or how wet the soil stays. The far north, the White Mountain valleys and higher elevations sit at the cold end. The seacoast and the southern tier sit at the mild end. Other parts of the state land in between, and a site a couple of miles away, at higher elevation, can be a full zone colder.
Which types clear zone 3b without help?
Rugosa roses and the Canadian Explorer series. Rugosas, descended from the beach rose of northeast Asia, are rated for zone 3 or colder. Their wrinkled leaves also shrug off road salt and sandy soil, which suits plantings near the coast and along salted roads. The Explorer roses were bred by Canadian breeders for prairie and Quebec winters, and most of the shrubs and climbers in that group are rated for zone 3 or colder as well, but check the rating of each variety. In a hard winter the tips of a few canes may brown, but the plant leafs out again from live wood.
Where do hybrid teas fall short?
Hybrid teas, floribundas and grandifloras are generally rated for zone 5 or 6. Across most of New Hampshire that means they live on the edge. Canes above the snow line often die back, and in zone 4 or colder a grafted hybrid tea can lose everything above the ground in a normal winter. A plant that is rated for your zone is not the same as a plant that keeps its top growth. Its roots survive, but the canes may not.
Snow is the great equalizer. A deep, steady snowpack insulates canes the way a quilt does, and a winter with bare ground and hard wind does damage that the zone number never predicts. A simple spring test settles most doubts: scratch a cane with a thumbnail. Green underneath means alive. Brown or tan means dead, and that wood should be cut back to the first green tissue.
Named roses that hold up here
These are the cultivars most likely to be on a nursery bench or in a mail-order catalog, with the zone rating growers and nurseries give them.
| Rose | Type | Rated zone | What it survives |
|---|---|---|---|
| Hansa | Rugosa shrub | 3 | Cold, wind, road salt, poor soil |
| Therese Bugnet | Hybrid rugosa shrub | 3 | Cold nights in the North Country |
| William Baffin | Explorer climber | 3 | Cold and exposed sites |
| John Cabot | Explorer climber | 3 | Cold winters |
| Knock Out | Landscape shrub | 5 | Winters in the milder southern part of the state |
| New Dawn | Climber | 5 | Typical zone 5 and 6 winters with some cane loss |
Hansa is the one to plant if you want a rose that asks for nothing. It is a double, magenta-purple rugosa with a strong clove scent, and it throws orange-red hips in fall. Therese Bugnet is softer, a pink shrub with reddish canes, and it grows tall and loose, so give it room. Both are fine well above the Notch, though neither repeats as heavily as a modern shrub rose.
William Baffin and John Cabot cover the climbing need. They are stiff, upright climbers that bloom heavily in early summer, and the Explorer series was designed so that they can be left on the trellis for the winter. That is a real advantage in New Hampshire, where untying and laying down a big climber each November is a chore many gardeners give up on.
Knock Out belongs in the milder half of the state. Growers rate it for zone 5, and it does best in zone 5 and 6, which means the southern tier, the seacoast and the warmer river valleys. It has become the default landscape rose because it blooms from early summer to frost with little deadheading. Where winter temperatures fall below its rating, choose Hansa or an Explorer instead of gambling on it.
New Dawn is an old, tough climber with pale pink, scented flowers, and growers rate it for zone 5. In a typical zone 5 winter it can lose the tips of canes or more, so in spring cut dead canes back to green wood and expect it to rebuild. It tolerates shade better than most climbers, which helps on a north-facing fence.
Sold here, but not for this zone
Garden centers in New Hampshire buy from national growers, so the shelves in April look much like those in Virginia or Oregon. Several of the roses on them are marginal here, and the tag on the pot often shows only the hardiness range the supplier prints for every market.
Hybrid teas are a large group. Widely sold varieties such as Peace and Mister Lincoln are rated for zone 5 or 6 on most tags. They are grafted, they bloom best in a mild, long season, and they need protection even in the southern part of the state. Planted without it in zone 4 or colder, they are usually gone within a winter or two.
Tree roses, the lollipop-shaped standards sold in spring, are worse. The grafted trunk is the weak point, and a hard freeze can split it and kill the whole plant. Most New Hampshire gardeners treat them as container plants that move into an unheated garage for the winter, or as annuals.
English-style roses are another trap. Many are rated for zone 5 or 6, and the full, many-petaled flowers that make them attractive come at the cost of hardiness. Large-flowered climbers with hybrid tea blooms are in the same category, and because many flower on older wood, losing the canes can also mean losing the year’s flowers.
If you buy a marginal rose anyway, protection is the whole game. After the ground begins to freeze, and not before, mound 10 to 12 inches of soil over the base of each plant. Mounding too early keeps the plant growing and traps moisture against the canes. Rake up fallen leaves first, since they carry the spores behind many summer problems, which are covered in Rose Diseases in New Hampshire: What the Climate Here Actually Brings.
What to check on the label before buying
Start with the zone printed on the tag, then compare it to your own zone, not the state’s. A rose rated for zone 5 planted in a zone 4 yard is outside its rating, however good it looks in the pot. If the tag gives a range such as 5 to 9, the first number is the cold limit that matters.
Next comes grade. Bare-root roses are sold in grades, with Grade 1 the top one, followed by 1½ and 2. Grade 1 plants have the thickest, most numerous canes and the strongest root systems, and that extra reserve helps a young plant get through its first winter. A cheap Grade 2 bare-root rose often saves a few dollars and costs a season.
The third thing to check is whether the rose is grafted or own-root. A grafted rose has a cultivar budded onto a separate, hardier rootstock, and the swollen joint where the two meet is the bud union. An own-root rose is grown from a cutting and is the same variety from roots to tips. The tag or the catalog entry will say “own root” if that is the case, so look for the words “own root” on anything borderline.
That matters more the colder the site. In a hard winter, a grafted rose that dies to the ground may regrow from the rootstock, and what comes up is the rootstock’s rose, usually a single-flowered, rambling plant, not the one you paid for. An own-root rose that dies to the ground comes back as the same variety. In zone 3b to 4, where dieback happens often, that difference decides whether the plant is worth owning.
Checking this against your own county
Zone and frost dates vary within a single county, so confirm them locally. UNH Extension has county offices and plant-selection advice for each part of the state, and the staff know which roses have held up in nearby gardens.
For reference, the weather station at Concord’s airport has a last spring freeze falling between May 3 and May 15, and a first fall freeze between September 29 and October 7 (NOAA NCEI climate normals, based on the 30 to 70 percent probability band for 32 F). Gardens outside town, especially in low spots or at elevation, can see the last spring frost later and the first fall frost earlier than the airport does. Check your own zone before you buy, and use the airport dates only as a starting point.
Common questions
Can hybrid tea roses grow in northern New Hampshire?
They can survive in sheltered spots with a soil mound each fall, but they are short-lived in zone 3b and 4. A rugosa or Explorer rose gives much more reliable bloom there.
Is Knock Out rose hardy in New Hampshire?
Growers rate it for zone 5, and it does best in zone 5 and 6. That covers the southern tier and the seacoast. Colder areas fall outside its rating, so ask your county extension office before planting it.
Do rugosa roses need winter protection?
Generally no. Hansa and other rugosas are rated for zone 3 or colder and are usually left alone through winter. They also tolerate road salt and sandy soil, so they suit roadside and coastal beds.
How can I tell if a rose died over winter?
Scratch a cane with a thumbnail and look for green underneath. Wait until nearby shrubs have leafed out before giving up on it, because roses with live wood at the base can still send up new canes in late spring.