Most Maryland roses need protection only at the base, and only in the colder parts of the state. Grafted hybrid teas, floribundas and grandifloras get a mound of soil over the crown after a run of hard freezes. Tough shrub roses on their own roots usually need nothing. On the warm Eastern Shore and near the lower Bay, many gardeners can skip the job entirely. Here is how to sort your bushes into the right group and what to do for the ones that need help.
Do roses need winter protection in Maryland?
It depends on where you garden and what kind of rose you have. Maryland covers USDA hardiness zones 5b to 8a. That system rests on one number, the average annual extreme minimum temperature, so it describes the single coldest night of a typical winter. That night matters more to a rose than the average January. The mountains of Garrett and Allegany counties sit at the cold end. The Atlantic side and the lower Eastern Shore sit at the warm end. The big middle, from the Frederick valley through Baltimore and the Washington suburbs, falls in between.
Baltimore makes a good reference point, because it has a long, official weather record. Its first fall frost, defined as the first night at 32°F, typically arrives between October 23 and November 5. The last spring freeze typically falls between April 4 and April 13. Those are the 30 to 70 percent probability band from the NOAA NCEI 1991-2020 Climate Normals. Other parts of the state run on a different calendar, so treat them as a starting point for your own yard.
Which roses need a mound, and which can skip it?
The deciding factor is the graft union. That is the knobby swelling at the base of a grafted rose where the named variety joins a tougher rootstock. If a hard freeze kills that union, the canes die and the plant may regrow from the rootstock as a completely different rose. Own-root roses have no such weak point. Even when the canes freeze back, the plant regrows true to type.
- Grafted hybrid teas, grandifloras and floribundas: mound them in cold-winter zones.
- Roses in their first winter in the ground: mound them anywhere in the state except the mildest coastal spots.
- Own-root shrub roses and most old garden roses: leave them alone.
- Climbers: mound the base, and leave the canes on their supports.
In the warmest territories, the honest answer is no. Established roses along the lower Eastern Shore and near the Atlantic coast rarely face the kind of cold that kills a graft union, and piling soil on them only adds a chance of rot. Western Maryland is the opposite case, where mounding is routine. For help choosing bushes that handle cold with less fuss, see Roses That Hold Up in Maryland. For the bigger picture of growing roses in Maryland, start with the main guide.
| Area | Winter cold | Mound grafted roses? |
|---|---|---|
| Garrett and Allegany counties | Coldest in the state, zone 5b at the low end | Yes, every year, and start earlier in fall |
| Baltimore and central Maryland | Middle of the range, first frost typically October 23 to November 5 | Yes, every year |
| Eastern Shore and lower Bay | Milder, up to zone 8a | Optional for established roses, worthwhile for new plantings |
When to start, and what triggers it
Wait for the cold to tell you. Mounding on a calendar date, say Halloween, tucks the plant in while it is still growing. Warm soil under a blanket of fresh dirt keeps the roots active, and the plant keeps pushing soft new shoots that the first real freeze will kill. Those dead tips are an entry point for disease.
The trigger is a run of hard freezes. In practice that means once several nights in a row have dropped to 28°F or lower, the usual threshold for a hard freeze. A single frost does not count. The first light frost is just the signal to get ready. In the mountains of Garrett and Allegany counties the cold arrives sooner in fall and stays later in spring, so the same job happens earlier there. The Eastern Shore runs milder, and the trigger can slip into December.
How can you tell the rose is ready?
Watch the plant. After a few hard freezes the leaves yellow and drop, new growth stops, and the canes look dormant. Then check the ground. Push a trowel or screwdriver into the soil beside the bush on a cold morning. If the top inch is stiff and stays that way through the afternoon, the plant is asleep and you can mound.
You can set the stage earlier without harming anything. In late summer, stop fertilizing roses. In early fall, quit deadheading so the plants form hips, which tells them to slow down. Buy bagged soil and gather your materials in October, so you are not hunting for supplies in a cold snap. The pruning question is separate, and it belongs to spring, so see When to Prune Roses in Maryland for timing. In fall, only trim canes that are long enough to whip around in the wind.
The same logic runs in reverse in spring. Pull the mound back gradually once the worst cold has passed and the danger of hard freezes is over. Keep a few bags of soil handy in case a late freeze threatens the new shoots.
How to mound, and how deep
The graft union is what you are covering. Cut nothing back to do it, and leave the canes above the mound as they are. Bury the graft union under a cone of soil about 10 to 12 inches tall, measured from the soil line up. For a bush with a swollen, raised union, make the cone a little taller. The mound should reach well past the base of the canes, so the buds low on each cane sit inside it. If the cold kills the exposed canes above the mound, the buds below survive and regrow in spring.
Use bagged topsoil or a topsoil and compost blend, and keep it dry until you need it. Bagged soil beats soil dug from around the plant for three reasons:
- Digging beside the bush cuts into the shallow feeder roots, right before the coldest weather.
- The trench you leave behind collects water and freezes, which puts the roots at more risk than before.
- Soil from a rose bed can carry fungal spores from black spot and other leaf diseases, and you would be piling them onto the crown.
Build the mound in two passes. Pour soil around the base and work it gently between the canes with your hands, then add the second layer to reach full depth. Taper the sides so rain sheds off. Once the ground has frozen, you can add a loose layer of shredded leaves or straw over the mound for extra insulation. Do it only after the freeze, because mulch laid over warm ground gives voles a cozy shelter.
Keep the canes above the mound uncovered. They can take winter cold, and some may die back to the mound anyway. In spring they come back, and you prune out the dead wood once the buds swell. Remove the soil in stages, pulling a few inches at a time over a couple of weeks, so tender new growth is not shocked by sudden sun and wind.
What does not work in this climate
Maryland winters swing. A week of 20s can be followed by a 55-degree afternoon, then another freeze. Methods that work in a steady deep-freeze climate often fail here, because they trap warmth on the sunny days and the plant wakes up at the wrong time.
Why does plastic wrap hurt roses?
Plastic does not breathe. On a mild afternoon the air inside heats up and the humidity climbs. Canes that should be dormant start to break buds, and the trapped moisture invites cankers and gray mold. When the next freeze arrives, the soft new growth dies. Burlap is a better choice for a windy, exposed spot, but it is a windbreak and not a substitute for the mound.
What goes wrong with sealed rose cones?
Styrofoam cones are sold as an easy fix, and they do work in colder regions where winter stays cold. In Maryland, a cone left sealed turns into a small greenhouse on the first sunny thaw. The canes inside wake up and then take the next freeze. Mice and voles also move in, since the cone gives them a dry, wind-free nest right at the crown. If you use a cone at all, vent it on mild days and remove it as soon as the cold breaks. Most gardeners are better off with soil.
Is mulch piled early a problem?
Yes. Heavy mulch placed against the canes in October while the ground is still warm holds heat in the soil. The plant stays active, the crown stays damp, and rodents get cover for the whole winter. Mulch belongs on top of the mound after the ground freezes, and never earlier.
Checking this against your own county
Dates and zones give you the outline, and your own yard fills in the rest. University of Maryland Extension has county offices that know local frost patterns, and their Master Gardeners can tell you how cold your area runs. Elevation matters too. A few hundred feet of climb can push a hilltop into a colder zone than the valley a mile away, and low spots collect cold air on still nights. Call your county extension office before the first hard freeze if your garden sits high, low, or near the boundary between two counties.
Common questions
Do roses in Baltimore need winter protection?
Grafted roses do. Mound the base after a run of hard freezes, meaning several nights at or below 28°F. Own-root shrub roses generally need none.
Should I prune my roses before winter?
Only enough to stop tall canes from whipping in the wind. The real pruning waits for spring, when the buds begin to swell and you can see which canes survived.
When do I take the mound off?
Pull it back in stages in spring. In the Baltimore area the last freeze typically falls between April 4 and April 13, so start removing soil gradually in mid-April and keep bagged soil nearby in case a late freeze arrives. Mountain counties should wait longer.
What about roses in pots?
Container roots sit above ground and freeze much harder than roots in the ground. Move pots against a sheltered wall, or into an unheated garage or shed once the plant is dormant. Water lightly if the soil dries out. Skip the plastic wrap here too.