Homegrown: Oct. 23, 2011
How do you winterize and care for potted roses?
There are two issues in bringing a potted rose through the winter successfully: cold and water.
Many roses can be a bit marginal here in their cold hardiness to begin with, but they’re even more susceptible to cold damage in a pot.
The roots of plants are never as hardy as the tops. The top of a plant might be hardy to minus 10 degrees but the roots might die at 20 degrees.
That’s not a problem for a plant growing in the ground because the mass of the soil keeps it warmer than the air above.
Sure, the ground freezes, but it never gets as cold as the air temperature. However, in a pot, above ground with a limited volume of soil, surrounded now on the sides by that cold air, we can see damage because the soil in the pot will get a lot colder than the ground.
There are two options to solve this.
The first option is to move the pot to a spot that doesn’t get as cold. That usually means an unheated (and often uninsulated) garage, shed or root cellar. It’s very important that the plant stay cold enough to remain dormant (otherwise you’ll open a whole new can of worms) but still be protected from the worst of the bitter winter cold.
The second option is to insulate the pot so the roots don’t get as cold. I’ve seen people wrap fiberglass insulation around their pots, which may not be all that attractive, but mostly effective, or just pile chopped leaves, straw or cedar mulch up around the pot to protect it.
Another method that’s the surest way to get the plant through the winter is to dig a hole somewhere in the garden late in the fall before the ground freezes and set the pot down into it.
Then fill the hole in with some of the soil excavated out or with chopped leaves or straw if you want to keep the pot cleaner.
The second issue I mentioned was water. We lose many potted plants over the winter because of drought.
It often surprises people to learn that a plant can be damaged by drought in the winter, but the truth is that drought will hurt or kill a plant every bit as much in January as it will in July. The only difference is that things won’t dry out as quickly in the winter as they do in the summer.
As a starting point, you should plan on giving your rose a good soaking every two to four weeks through the winter depending on the weather, exposure, and size of the pot.
You don’t have to maintain a “perfect” watering schedule, just keep in mind that it should be done.
If the pot is smaller, out in the sun and the weather is warmer than normal without any precipitation, then twice a month is a pretty good guide.
However, if we have a lot of moisture or heavy, consistent snow cover, you can probably put the clock on hold and wait for things to melt and start to dry again before watering.
The last thing I’ll mention is that doing this can sometimes be hard on the pot itself.
Since you must maintain moisture in the soil, that water can degrade or break some pots. Be careful with ceramic or red clay pots, they are the most common types to suffer damage over the winter. Plastic or wood are the safest and concrete usually persists, but the moisture can cause some of the surface concrete to flake off.