Yes, for most roses in Indiana. After a run of hard freezes, pile 10 to 12 inches of clean soil over the base of each plant. Hardy shrub roses in the southern counties can often skip it. Grafted types such as hybrid teas should not. Below you’ll find the timing, the depth, and the popular wrappings that do more harm than good. For care during the rest of the year, see our guide to growing roses in Indiana.
Do roses need winter protection in Indiana?
The USDA Plant Hardiness Zone Map puts the state in zones 5b to 7a. That system rests on a single variable, the average annual extreme minimum temperature. Indiana spans zones 5b to 7a on the USDA Plant Hardiness Zone Map, which is built on the average annual extreme minimum temperature. The northern tier sits at the cold end and the Ohio River counties at the warm end. Indianapolis falls in between, and other parts of the state differ, so check your own zone on the USDA Plant Hardiness Zone Map.
Most hybrid teas, floribundas and grandifloras are budded onto a separate rootstock. The weak point is the graft union, the swollen knob where the canes meet the roots. If cold kills the union, the named rose is gone. What often comes back is a rootstock sprout with small, plain flowers. The zone number is also an average, and any single winter can run colder than it. The bigger danger is a stretch of mild days followed by a hard drop, which pulls a plant out of dormancy and then punishes it.
Which roses can skip winter protection in southern Indiana?
Along the Ohio River, where zone 7a pockets appear, the honest answer is often no. Own-root shrub roses bred for cold regularly get through without help. Grafted roses are the exception even there, because one hard winter can undo years of growth. In the central and northern counties, protect anything grafted every year. Open, windswept sites in zone 5b are the hardest on roses, and lake-effect snow cover in the far north helps only plants that are buried under it. Roses with a track record here are covered in Roses That Hold Up in Indiana.
When to start, and what triggers it
The calendar is the wrong trigger. Mounding while a rose is still growing holds warmth around the crown and keeps the plant from hardening off. At the Indianapolis station, NOAA’s 1991-2020 Climate Normals put the first 32°F freeze between October 21 and October 30. That first freeze is only a warning shot, because roses keep trying to grow through it. Wait for several nights in a row at or below 32°F. In central Indiana, watch the forecast and the plants themselves as the season winds down. The north gets there earlier, and southern Indiana runs later in autumn by a fortnight or more.
A rose that is ready shows it. Leaves have yellowed, dropped or been blackened by frost, and no new shoots are pushing. The soil surface is cold and stiff in the morning. If the plant still looks active, hold off a week and check again.
What should you do before the hard freezes arrive?
Use the weeks in between for preparation. Stop fertilizing in late summer, so the plant isn’t pushing soft new growth into fall. Rake up fallen leaves around the bush, since they carry black spot spores through winter. Buy your soil early and store the bags in a garage or shed. A bag left outside can freeze into a solid block, and you’ll be chipping at it just when you need it loose.
Check the weather before you commit, too. If a forecast shows a week of 50s after the first cold snap, keep the soil bagged and wait. Mounding too late costs little, and a mild stretch in early winter happens often enough that a late start rarely hurts. Mounding too early can leave you with a plant that sprouts under the soil.
How to mound, and how deep
The target is the graft union, not the canes. Cover the base of the plant with soil to a height of 10 to 12 inches, so that you bury the graft union and the lowest few inches of every cane. The tops above the mound often die back in a hard winter anyway. You’ll trim that dead wood in spring (timing is covered in When to Prune Roses in Indiana). What you’re saving is the buried portion, because that is where the new canes will come from.
Mound with bagged topsoil, garden soil blend or compost, and plan on enough bags to cover each plant. Bagged material is loose, drains well and carries no leftover disease from your beds. Soil scraped from around the plant does the opposite. It strips the shallow feeder roots near the crown, and it leaves a shallow trench that fills with meltwater and freezes right against the plant. It can also carry fungal spores from the summer’s leaf spots. Bring the soil in from outside the bed instead.
Tie the canes loosely together first, and trim only the long tips that would whip around in wind. Once the ground has started to freeze, you can add a loose layer of straw, shredded leaves or evergreen boughs over the mound. That layer keeps the soil from thawing and refreezing, and it matters more than most people expect. Late winter in Indiana often swings from the 50s to the teens within days.
What about climbers and tree roses?
Climbers get the same mound at the base. Leave the canes on their support and wrap exposed stretches loosely in burlap, which breathes. Tree roses are the exception to the mounding rule, because the graft sits at the top of the trunk, well above any mound. They need to be moved to an unheated garage or laid down and buried in a trench, and that is a bigger job than the rest of this list.
What does not work in this climate
Plastic wrapping is the worst offender. Plastic doesn’t breathe, and a sunny January afternoon can heat the inside while the outside stays cold. Condensation collects, canes stay damp, and rot and fungal cankers set in. The warmth also wakes the plant, and the next hard freeze hits tissue that has just started to move. If you want to wrap canes, use burlap and leave it loose.
Why do sealed rose cones fail?
Foam rose cones sold at garden centers act the same way. Sealed over a plant, they trap heat on sunny days, which can push buds to swell in the middle of winter. Voles and mice also find the dry, sheltered space and chew the canes and crown. A cone only helps if it is vented, and you must vent or remove it on any sunny day above freezing. Most gardeners find that unrealistic over a whole winter, which is one reason a soil mound is the better choice here.
Mulch piled while the ground is still warm causes a quieter problem. A thick blanket of leaves, straw or wood chips put down while the soil is still warm holds the soil warm and wet, and the crown stays active when it should be shutting down. That same cozy layer attracts rodents. With first freezes arriving between October 21 and October 30 at the Indianapolis station, a pile built in early fall is weeks too early. Wait for the cold, then mulch on top of the mound after the surface has started to freeze.
Checking this against your own county
Frost dates and zone lines are broad. Southern Indiana runs earlier in spring and later in autumn than the north by a fortnight or more, and the Indianapolis dates here are a reference point. Elevation matters at a smaller scale. Cold air drains downhill and pools in low spots, so a rose in a hollow can freeze before one on a slope a few hundred feet away. For local guidance, call your county office of Purdue Extension. Its staff know the local microclimates and the winters that caught gardeners off guard. You can find your county office through Purdue Extension.
Common questions
Can I use leaves or straw instead of soil?
Not alone. Leaves mat down and stay wet, and straw is a favorite nesting spot for voles. Soil is the base layer. Add straw or shredded leaves on top of the mound after the ground has begun to freeze, if you like.
When do I take the mound off?
Pull it away gradually in spring. At the Indianapolis station, the last 32°F freeze usually falls between April 9 and April 21. Purdue Extension notes roughly a 10% chance of a freeze after the published spring date, so keep a cover or a few bags of soil handy. Remove about half the mound first, check for new growth, and finish when the weather settles. Pull the mound off too late and shoots grow pale under the soil.
Do potted roses need protection too?
Yes, and they need more of it. A pot lets cold reach the roots from all sides, where in-ground roots are insulated by the earth. Move the pot to an unheated garage or shed after dormancy, or sink it into the ground and mound over it. Water it lightly once or twice over the winter if it stays in a dry spot.
Should I water roses before winter?
If fall has been dry, give the bed a deep soaking before the ground freezes. Moist soil holds heat better than dry soil, and roots that go into winter thirsty are more likely to suffer. Stop watering once the soil is frozen.