Growing roses in a cold climate: the complete guide

Growing roses at a glance

Contents

• Growing roses at a glance
• Which type of rose should you grow?
• Cold-hardy roses worth buying
• Own-root or grafted roses?
• Bare-root or containerised?
• Where to plant roses
• How to plant a rose step by step
• Spacing and how many plants
• How often should you water roses?
• Feeding and the late-July cut-off
• Mulching and underplanting
• Pruning and deadheading in brief
• What are rootstock suckers?
• Black spot, rust, mildew and pests
• Rose replant disease
• Winter protection and the Minnesota tip
• Roses in containers
• Climbers and ramblers
• The rose year, month by month
• Zone table: roses in USDA zones 3–6
• Common mistakes
• Frequently asked questions

Which type of rose should you grow?

This is the decision that determines how much work you sign up for. A rugosa and a hybrid tea are both roses in the way a pine and a peach are both trees; the workload differs by a factor of ten. Classes are defined by growth habit and ancestry, not flower colour. In zone 3 and 4 most run shorter than the heights below, because the canes die back each winter.

Read the table from the bottom up if you are unsure. And a once-blooming rose is not a stingy one — a gallica in full June flush carries more bloom at once than a hybrid tea produces all season.

Cold-hardy roses worth buying

The Canadian series

The Explorer series was bred in Canada for the prairie winter. It runs to 25 cultivars, including 'John Cabot', 'William Baffin' and 'Henry Kelsey', and North Carolina State Extension rates the group hardy to zone 3a with a few to 2a, with extreme resistance to black spot and mildew.

The Parkland or Morden series came out of Manitoba and is hardier still. The Canadian Rose Society lists 'Adelaide Hoodless', 'Morden Centennial' and 'Morden Ruby' at zone 2 and about 1 m (3 ft), 'Morden Blush' and 'Winnipeg Parks' at zone 2b, and 'Morden Sunrise' at zone 3. 'Morden Blush' flowers from June to freeze-up, and nearly all are own-rooted.

Rugosas

Rugosa species and hybrids tolerate cold to zone 2, along with disease and road salt, and most repeat all summer. The wrinkled foliage almost never gets black spot, the hips are large and edible, and they thrive in sand where other roses sulk. Many sucker, so plant them where spreading is an asset.

American shrub roses

Griffith Buck bred roses at Iowa State University in the 1970s on almost no budget, which forced him to select for plants that survive an Iowa winter without spraying or protection. 'Carefree Beauty' is the famous one: pink, 90–150 cm (3–5 ft) high and wide, flowering from June until frost, and named by the Missouri Botanical Garden as black-spot-resistant.

Iowa State Extension groups the Knock Out, Explorer, Easy Elegance and Oso Easy series as landscape roses that are winter hardy in Iowa without extra protection, own-rooted and resistant to black spot and mildew. That is the shortest route to a rose that simply works.

Old garden roses

Many albas, gallicas, damasks and mosses are hardy to zone 4, which surprises people who assume antique means tender. They bloom once, in early summer, and do it every year without help. The trade-off is that single flush.

Own-root or grafted roses?

A grafted rose is a named cultivar budded onto the roots of a tough wild rose. An own-root rose is the cultivar growing on its own roots, from a cutting or tissue culture. In a mild climate the difference is academic; in zone 3 to 5 it decides whether your rose survives as itself.

When a hard winter kills a grafted rose to the ground, whatever regrows comes from the rootstock, and you end up with a wild rose wearing your cultivar's label. When the same happens to an own-root plant, the new shoots are still the cultivar you bought. The Twin Cities Rose Club puts it plainly: own-root plants are typically more amenable to cold climates.

Own-root roses are smaller in year one and take a season longer to reach full size. Grafted plants give a bigger bush faster, and some cultivars are only sold grafted. If you buy grafted in zone 3–5, plant the bud union deep and mound it every autumn.

Bare-root or containerised?

The same cultivar sells in two forms. Bare-root plants are lifted from the field without soil and shipped dormant; containerised plants carry an intact root ball.

Ten roses for a hedge means bare-root and half the cost; one rose in July means a container. A good bare-root plant feels heavy and has pale, moist roots — if they are brittle and brown, leave it. If a container rose has roots circling the pot wall, tease the outer layer loose.

Where to plant roses

Sun first. Roses want at least six hours of direct sun; the RHS puts the absolute minimum at four. Below that you get thin growth and more disease.

Air second. A rose boxed in between a hedge and a fence sits in damp air all morning, and black spot spores need seven hours of continuous leaf wetness to infect. A site where sun and wind dry the foliage by nine halves the problem.

Water last, in the sense that it must leave. Roses tolerate drought far better than standing wet. Dig a hole 45 cm (18 in) deep and fill it; if it drains within five or six hours, drainage is adequate.

Soil should be rich and moisture-retentive at pH 6.0–7.0, which most garden soils manage on their own. Work 5–10 cm (2–4 in) of compost through the whole bed, 60–75 cm (24–30 in) wide and 45 cm (18 in) deep. On heavy wet ground a raised bed is the simplest answer — the same logic as raised-bed growing.

How to plant a rose step by step

Depth is the step people get wrong. For grafted roses in zone 3–5 the bud union should sit 8–10 cm (3–4 in) below the finished soil surface, so the graft is insulated and the cultivar can reshoot if the top freezes. Own-root roses go in at pot depth.

1. Soak first. Bare-root plants go in a bucket for 6–24 hours, no longer — roots need oxygen. Containerised plants go in a tub until bubbling stops.
2. Dig a hole wider than deep, roughly 50–60 cm (20–24 in) across.
3. Loosen the base with a fork so roots can carry on downward.
4. Mix the excavated topsoil with compost, one part to two.
5. Build a cone of soil in the bottom and set the plant on it, roots spread down the sides.
6. Check the depth with a cane across the hole: bud union 8–10 cm (3–4 in) below grade, crown at soil level for own-root plants.
7. Backfill halfway, water with about 10 litres (2.5 gal) and let it drain.
8. Backfill the rest, firming at the edges but never over the roots.
9. Water again with about 10 litres (2.5 gal) so soil settles around every root.
10. Mound 10–15 cm (4–6 in) of soil over the canes of an autumn-planted bare-root rose.
11. Mulch 5 cm (2 in), leaving 10 cm (4 in) of bare soil around the stems.
12. Water weekly through the first season, more in heat.

Spacing and how many plants

Roses go in closer than people expect, because a group should read as one mass. The RHS suggests about 60 cm (2 ft) around a border rose. Air still has to move, so resist squeezing in one more.

Keep any rose at least 50 cm (20 in) out from a house wall, for air movement and because the strip against a foundation is the driest ground you own.

How often should you water roses?

Seldom and deeply. Roses need roughly 2.5 cm (1 in) of water a week and more in heat — in practice 5–10 litres (1–2.5 gal) per plant, in one go rather than seven small doses.

The reason is root depth. A rose sends roots well over a metre down if given cause. Daily sprinkling keeps only the top few centimetres moist, so roots stay up there, where they dry out first and freeze worst.

Water at the base, never over the leaves, and in the morning if you must wet foliage at all. Newly planted roses are the exception: a weekly soak through the whole first season regardless of weather.

Feeding and the late-July cut-off

A rose planted into well-prepared soil rarely needs feeding in year one. From year two, feed two or three times.

Start in early to mid May, once new growth shows, with a balanced granular fertiliser — the RHS rate for border roses is 70 g per square metre (2 oz per sq yd). Feed again after the first flush, and in mid July if plants are working hard.

Then stop the nitrogen. Twin Cities Rose Club puts the cut-off at late July, and it is the rule that saves the most roses in zone 3 and 4. Late nitrogen pushes soft growth that cannot harden before frost. If you want to feed in late summer, use potassium: it helps canes harden and makes foliage less prone to fungus.

Mulching and underplanting

A 5 cm (2 in) layer of compost, rotted manure or leaf mould conserves moisture, suppresses weeds and feeds the soil. Leave 10 cm (4 in) of bare soil at the stems so it does not hold damp against the crown. Missouri Botanical Garden recommends leaf mould as part of a black-spot programme, because it buries the overwintering spores.

Underplanting earns its keep. Low perennials between roses shade out weeds and give the bed something to look at between flushes. Catmint, low salvias and lamb's ear are the classic partners; the principles are in the guide to companion planting, with more candidates among perennials for full sun. Keep them clear of the rose's stems.

Pruning and deadheading in brief

In a cold climate the timing rule is simple: prune in spring, once buds swell and you can see which wood survived. Autumn pruning opens wounds and pushes growth that winterkills. In zone 3 that means May; in zone 6, April.

What you do then depends on the class. Hybrid teas and floribundas need a hard cut. Once-blooming old garden roses flower on last year's wood and are pruned right after flowering instead — cut them in spring and you remove the entire season's bloom. The class-by-class cuts are in the guide to pruning roses.

Deadheading is easier. Repeat bloomers rebloom faster if you cut spent flowers back to the first full five-leaflet leaf, not just the faded head. Do not deadhead once-bloomers — the hips are the point in autumn. Stop by late August so the plant hardens off, and pick up fallen leaves all season; it is the most effective thing you can do about black spot.

What are rootstock suckers?

If your rose is grafted, the rootstock has dormant buds of its own. When they break you get suckers: vigorous wild-rose shoots that take over the plant in two or three years if you let them.

• They come from below the graft, often a short way out into the soil.
• The leaves usually carry seven leaflets where many cultivars carry five, in a different green.
• The shoot grows straight and fast, more vigorous than the rest of the plant.
• The thorns are denser and sharper, on coarser stems.
• The flower settles it — let a sucker bloom and you get a single pale pink wild rose.

Never cut a sucker off at ground level — the cut acts like a pruning cut and the rootstock answers with two more. Scrape the soil back until you find where the shoot joins the root and tear it off downward. If it will not budge, cut it flush so no stub remains, then check again a month later.

Own-root roses never sucker in this sense — any shoot from the base is the same cultivar.

Black spot, rust, mildew and pests

Three fungal diseases account for most rose trouble in the north.

The measures overlap: collect leaves, water at the base in the morning, keep things open and hold back on nitrogen. Cultivar choice is strongest of all — rugosas and the Explorer series shrug all three off, while yellow hybrid teas are the most susceptible.

Pests

Aphids are almost never a real threat. They are unpleasant for three weeks in June and then they get eaten. Do not spray broadly — that takes out the ladybirds too.

Rose replant disease

Plant a new rose exactly where an old one stood and it often sulks even when everything else is right. The RHS calls rose replant disease a recognised but poorly understood problem: the new plant fails to put on decent growth and fine roots may rot. The cause is thought to be a build-up of soil pests and pathogens over the life of the first planting, and it can persist at least nine years. The fix is to swap the soil in a zone about 60 cm (24 in) across and 30 cm (12 in) deep for soil from a part of the garden where roses have not grown. Roses budded on Rosa 'Laxa' are less susceptible than those on Rosa canina.

Easiest of all: plant the new rose half a metre to one side. Same reasoning as crop rotation — move the plant, not the problem.

Winter protection and the Minnesota tip

Most roses in zone 3–5 are killed not by cold alone but by the swing between bare frost, thaw and hard late-winter sun. Protection keeps the crown evenly cold and shaded.

Mounding

Mound 25–30 cm (10–12 in) of soil over the base of each plant in late autumn, once growth has stopped but before the ground freezes hard, holding it with a wire cylinder. Bring soil in from elsewhere rather than digging into the rose's root zone, and top it with loose leaves once the ground has frozen. Uncover in early to mid April.

The Minnesota tip

For tender grafted roses in zone 3 and 4, the American Rose Society's North Central district describes the classic method. In mid to late October, clear old mulch and lace the canes together with synthetic twine that will not rot, leaving a long tail above the tie. Dig a trench on one side and loosen the soil at the base with a fork. Tip the whole plant into the trench, bending it just under the graft, and cover it with the soil you removed, leaving the twine showing. Water it in. In early November add a blanket of leaves 30–45 cm (12–18 in) deep, wet them down, and tuck rodent bait inside. Take the leaves off in early April and reverse the rest by mid April.

It is a serious amount of work, which is the argument for own-root shrub roses. Rugosas, Explorer and Parkland roses and the landscape series need none of it.

Roses in containers

Roses grow well in pots; the pot is usually just too small. Allow at least 40 litres (10 gal) for a compact rose and 60–80 litres (15–20 gal) for a shrub, as deep as it is wide. Use a heavy loam-based compost rather than a light peat mix, empty the saucer after every watering, and water by the finger test — dry 3 cm (1 in) down means water, which can mean daily in July. Feed fortnightly from May to the late-July cut-off.

Overwintering is the hard part: soil in a pot freezes from every side, and roots tolerate far less cold than canes. Push pots against a wall, wrap them, stand them on insulation and group them together. An unheated garage near freezing works too, as long as the compost never dries out.

Climbers and ramblers

Roses do not climb. They have no tendrils and no adhesive pads — they lean on things and hook on with their thorns, so without tying in they fall away from the wall.

Climbers carry stiffer canes 1.5–6 m (5–20 ft) long and usually repeat; 'William Baffin', 'Henry Kelsey' and 'John Cabot' are the cold-climate standards. Ramblers are larger, with one spectacular midsummer flush, and suit a pergola or an old apple tree rather than a small wall.

Set the plant at least 50 cm (20 in) out from the wall and mount trellis on battens so there is a 5–10 cm (2–4 in) air gap behind it. The key technique is to train main canes horizontally or in arcs: a vertical cane flowers only at the tip, while a bent one breaks buds along its whole length. Check the ties each spring so they do not strangle.

The rose year, month by month

Timings suit zone 4 and 5. In zone 3, shift spring work two weeks later and autumn work two weeks earlier.

Zone table: roses in USDA zones 3–6

The table is a starting point, not a promise: a south-facing, well-drained bed against a wall behaves like a zone warmer, a clay hollow in shade like a zone colder. Zone 3 is prairie Canada, zone 4 much of the upper Midwest and southern Ontario, zone 5 upstate New York and the Scottish Highlands, zone 6 most of Britain.

The care level drops as you go north, because the only classes that survive there are the tough ones. And the pruning window moves about six weeks between zone 6 and zone 3, so a date copied from a British book can be badly wrong in Manitoba.

Common mistakes

• Planting a grafted rose too shallow. In zone 3–5 the bud union belongs 8–10 cm (3–4 in) below grade, or the rootstock takes over.
• Feeding nitrogen after late July. It pushes soft growth that cannot harden off.
• Light, frequent watering over the leaves. Shallow roots plus seven hours of leaf wetness is what black spot wants.
• Pruning every rose the same way in spring. Once-bloomers flower on last year's wood, so a spring cut removes the whole season's bloom.
• Pruning in autumn. Late cuts open wounds and push growth right before winter.
• Cutting suckers at soil level. The cut acts as a pruning cut and two more come back. Dig down and tear them off at the root.
• Replanting exactly where an old rose stood. Replant disease persists at least nine years. Swap the soil or move half a metre.
• Leaving diseased leaf litter. Black spot overwinters in fallen leaves; an autumn rake-up is the cheapest control there is.

Frequently asked questions

When is the best time to plant roses?
Containerised roses go in any time the ground is workable, ideally late spring. Bare-root roses are planted dormant: late autumn in zone 5 and 6, or early spring elsewhere. In zone 3 and 4 spring planting is safer, because the plant gets a full season before its first winter.

How deep should you plant a rose?
For a grafted rose in zone 3–5, set the bud union 8–10 cm (3–4 in) below the finished soil surface so the graft is insulated and the cultivar can reshoot from below. In zone 6 and warmer, at or just below grade is enough, and own-root roses go in at pot depth. Check with a cane laid across the hole.

Are own-root roses better than grafted ones?
In a cold climate, usually yes. If winter kills a grafted rose to the ground the regrowth is rootstock and the cultivar is gone, while an own-root plant comes back as itself. They also never throw wild suckers. The trade-offs are a smaller plant in year one and a narrower choice of cultivars.

How much sun do roses need?
Six hours of direct sun is the working target, and four is the absolute minimum the RHS gives. Below that you get sparse growth and more disease. Air matters nearly as much: black spot needs seven hours of continuous leaf wetness to infect, so a place where morning sun dries the foliage early beats an afternoon-sun spot.

How often should you water roses?
Give about 2.5 cm (1 in) a week through the season, more in heat — roughly 5–10 litres (1–2.5 gal) per established plant, all at once rather than in daily sips. Deep, infrequent watering drives roots down. Water at the base, and soak newly planted roses weekly through the first season.

Which roses are hardiest for zone 3?
Rugosas tolerate zone 2, as do several Parkland roses: the Canadian Rose Society rates 'Adelaide Hoodless' and 'Morden Centennial' at zone 2, and 'Morden Blush' and 'Winnipeg Parks' at zone 2b. The Explorer series is rated to zone 3a, a few to 2a. All are sold on their own roots, which is what makes them dependable that far north.

Why does my rose have black spots on its leaves?
That is black spot, caused by Diplocarpon rosae. The lesions are dark and round with fringed, radiating edges, and leaves drop from the bottom up. Spores need seven hours of continuous wetness to infect and overwinter in fallen leaves and canes. Remove infected leaves, rake the bed clean, water at the base and choose resistant cultivars.

Do roses need winter protection?
It depends on the class. Own-root rugosas, Explorer, Parkland and landscape roses come through zone 3 with nothing. Grafted hybrid teas and floribundas need 25–30 cm (10–12 in) of mounded soil in late autumn plus a leaf blanket once the ground freezes; in zone 3 many growers tip them instead.

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